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EFFECTIVE

• Dyspepsia. Oral calcium carbonate is approved by the US Food and Drug Administration (FDA) as an antacid. Details: Taking calcium carbonate orally as an antacid is effective for treating dyspepsia (1843). Calcium carbonate has FDA approval as an antacid.
• Hyperkalemia. Intravenous calcium gluconate is approved by the US Food and Drug Administration (FDA) for preventing hyperkalemia-induced cardiac abnormalities. Details: Administering calcium gluconate intravenously can reverse electrocardiographic changes and arrhythmias induced by hyperkalemia (12946). Intravenous calcium gluconate is FDA-approved for preventing hyperkalemia-induced cardiac abnormalities.
• Hypocalcemia. Oral calcium treats and prevents hypocalcemia. Intravenous calcium is used to treat severe hypocalcemia. Details: Taking calcium orally is effective for treating and preventing hypocalcemia. Intravenous calcium gluconate, acetate, gluceptate, or chloride is effective for severe hypocalcemia or hypocalcemic tetany (12928).
• Kidney failure. Oral calcium carbonate or calcium acetate is used as a phosphate binder during kidney failure. Details: Taking calcium carbonate or calcium acetate orally is effective as a phosphate binder. Calcium acetate (PhosLo) appears to control hyperphosphatemia better than sevelamer (Renagel) (12943,12944,38990). Calcium citrate is not recommended for this purpose because it increases aluminum absorption and does not bind phosphate as efficiently as calcium acetate or calcium carbonate (21631). Some clinical research also shows that taking calcium orally reduces blood pressure in patients with kidney failure (975).

LIKELY EFFECTIVE

• Corticosteroid-induced osteoporosis. Oral calcium in combination with vitamin D prevents bone density loss that occurs during long-term treatment with corticosteroids. Details: Taking calcium in combination with vitamin D as adjunctive therapy seems to be effective for reducing bone mineral density loss in people using corticosteroids long-term (982,1046,1830,1831,1832,4462,4463,4464,4465,4466)(4467,12945,38493). One specific product used in clinical research is Oscal (Marion Merrel Dow Inc.), which contains elemental calcium 500 mg per tablet plus vitamin D 125 IU per tablet (982). Another product used is Oscal 250 + D (SmithKline Beecham Healthcare), which contains elemental calcium 250 mg and vitamin D 125 IU per tablet (1046).
• Hyperparathyroidism. Oral calcium reduces parathyroid hormone levels in patients with secondary hyperparathyroidism due to kidney failure. Details: Taking calcium orally reduces parathyroid hormone levels in patients with kidney failure and secondary hyperparathyroidism (1827,1828,1829,39174,39425). In elderly women, the combination of calcium and vitamin D reverses secondary hyperparathyroidism and reduces hip fracture risk (8818). Also, population research suggests increased calcium intake from the diet and supplements reduces the risk of primary hyperparathyroidism in women. Supplemental intakes of at least 500 mg/day and dietary intakes of approximately 1100 mg/day are considered to be protective (91353).
• Osteoporosis. Adequate calcium intake, from the diet and/or supplements, is recommended for the prevention and treatment of osteoporosis. Details: The Bone Health and Osteoporosis Foundation (BHOF) recommends ensuring adequate calcium intake in line with the recommended dietary allowance (RDA) by age, along with adequate vitamin D intake, for the prevention and treatment of osteoporosis in adults over 50 years of age. Supplementation can be used to augment dietary intake when adequate dietary intake is not feasible (109425). In the US and Canada, foods containing at least 200 mg calcium with less phosphorous content than calcium can be labelled with a health claim regarding the relationship between adequate calcium intake and a reduced risk for osteoporosis (11940,102148). However, calcium supplementation is not recommended specifically for the primary prevention of osteoporosis. The US Preventive Task Force (USPSTF) states that the current evidence is insufficient to assess the balance of benefits and harms of vitamin D and calcium supplementation, alone or in combination, for the primary prevention of fractures in community dwelling adults without osteoporosis (95695). Also, calcium supplements do not seem to be effective for preventing loss of bone mineral density (BMD) during lactation (988), in patients who have had bone marrow transplantation (1817), or in patients who have had renal transplantation (4823,38736,38871). Maximal bone growth occurs in the teenage years, and then BMD in females remains relatively constant until age 30-40. After age 40, bone loss typically occurs at rates of 0.5% to 1% per year. In males, this occurs several decades later. Bone loss is more pronounced if dietary calcium intake is below the RDA, which is the case for many Americans (2571,2578). One meta-analysis of randomized controlled trials in healthy children 7-14 years old shows that fortifying food with calcium 250-1000 mg daily for up to 24 months modestly improves femoral neck BMD, but not hip or spine BMD. However, the included trials did not supplement vitamin D (107232). During the 5 years immediately after menopause, calcium supplementation has very little effect on bone loss (2569,2570,2575,2576). The rapid loss of estrogen causes a high bone resorption rate, which increases serum calcium levels and therefore decreases intestinal absorption of calcium (2570). After this period, the typical rate of bone loss is 2% per year (2572,2576). Taking calcium 1000-1600 mg daily as carbonate, citrate, lactate gluconate, or citrate malate salt decreases this rate by 0.25% to 1% annually (977,979,981,2569,2571,2572,2575,2576,2578,6850)(38978,38980,39064). The greatest reductions (1% or more) are seen in the first 1-2 years of supplementation when bone remodeling foci can be filled (2569,2576). After this period, the differences in rate of loss between supplemented and non-supplemented females are closer to 0.25% per year (2569,2577). A meta-analysis of clinical evidence suggests that there is no additional benefit after 4 years (38980). Small clinical studies have found that continuous calcium supplementation at an average daily dose of 1050 mg, started after menopause and continued for 1.5-4 years, may reduce fracture rates by 26% when compared with no calcium supplementation. The largest of these studies was conducted in nursing home residents who also received daily vitamin D; the benefits of calcium, specifically, are unclear (39386). Some research also suggests that calcium and vitamin D improves primary prevention of osteoporotic fractures in some older individuals with osteoporosis, particularly the elderly and those who are no longer community dwelling (12930,38875,38849,39026,109471). However, not all research is positive. One large clinical trial in elderly adults with a low-trauma fracture show that taking calcium 1000 mg daily with or without vitamin D 800 IU daily for 2-7 years does not reduce the risk of a second fracture when compared with placebo (13073). Another clinical study shows that taking calcium 1000 mg daily plus vitamin D 800 IU daily does not prevent a second fracture in elderly patients, or prevent a first fracture in elderly patients with other risk factors such as low body weight (less than 58 kg, 127.6 pounds), smoking, family history of hip fracture, or fair or poor self-reported health (12929). Also, some exploratory research suggests that supplements may need to be continued indefinitely; in adults over 68 years of age, any effects of 2 years of calcium supplements on BMD appear to be lost within 2 years after discontinuing supplements (6853). Calcium has additive effects when used with other agents such as vitamin D, estrogens, or calcitonin. Whereas calcium alone generally reduces or prevents loss of BMD, combination with other agents can produce small increases in BMD ranging from 0.3% to 3.3% depending on the combination and dosages used (978,980,1836,2570,2571,2572,2576). However, one meta-analysis in healthy adults shows that fortifying foods with calcium 250-1000 mg daily, in conjunction with vitamin D supplementation, for up to 24 months does not improve BMD when compared with control (107232). The full potential of osteoporosis treatments cannot be realized without adequate calcium intake (2569,2570,2571,2572). Advise patients taking agents such as estrogens, calcitonin, bisphosphonates, or raloxifene (Evista) to ensure that their daily calcium intake meets the RDA. Use supplements if necessary. The usefulness of calcium in preventing osteoporosis in males is not as well-studied. Some observational research has found that calcium 870 mg daily is not associated with changes in BMD and bone loss in males (97201). However, clinical evidence suggests that taking calcium 1000 mg daily for 2 years might improve trabecular or cortical bone mass by 2% to 4% (980,8827,8873). Dietary supplementation with calcium and vitamin D seems to moderately reduce bone loss measured in the femoral neck, spine, and total body, and seems to reduce the incidence of nonvertebral fractures in older patients with osteopenia or low BMD (980).
• Premenstrual syndrome (PMS). Adequate calcium intake seems to prevent symptoms of PMS. Details: There seems to be a link between low dietary calcium intake and symptoms of PMS (2004,6847,39007). Taking calcium 1000-1336 mg daily seems to significantly reduce depressed mood, water retention, and pain, especially if daily calcium intake is inadequate (1822,1823,1824,2004,95821). Calcium carbonate 1200 mg daily seems to decrease PMS symptom scores by about 18% when compared with placebo (1822). Increasing dietary calcium intake is also associated with a decreased risk of developing PMS. Consuming an average of 1283 mg of calcium per day from foods is associated with about a 30% lower risk of developing PMS compared with consuming an average of 529 mg daily (13094); however, taking calcium supplements does not appear to be associated with the risk of developing PMS.

POSSIBLY EFFECTIVE

• Colorectal cancer. Oral calcium seems to be beneficial for preventing colorectal cancer, especially in those with adequate vitamin D levels and normal body mass index (BMI). Details: Population studies have found that increased intake of dietary or supplemental calcium is associated with a reduced risk of colorectal cancer and colorectal adenomas (1047,8820,12120,38951,98898,98899). Clinical trials and meta-analyses of clinical research also show that taking calcium supplements 1.2-2 grams daily for up to 4 years can reduce the risk of colorectal adenoma recurrence by up to 29% (970,12118,12950,15267,34596,38718,39042,95817). However, not all research has been positive. Some meta-analyses of clinical research or observational studies suggest that taking calcium does not reduce the risk of familial adenomatous polyposis or colorectal cancer (34596,39042,39349). Other contradictory research suggests that postmenopausal females who take calcium 1000 mg daily plus vitamin D 400 IU daily do not have a reduced risk of developing colorectal cancer (14290); however, this finding may not be reliable due to the high baseline intake of calcium in study participants. The reason for these conflicting findings is not entirely clear. Vitamin D might be an important factor. People with lower than average vitamin D levels do not seem to get any benefit from calcium supplements (12118). Also, one meta-analysis of previous trials suggests that taking calcium 1200 mg daily reduces the risk of colorectal adenomas in people with a normal BMI, but not in those who are overweight or obese (99715). Despite this conflicting evidence, the US Food and Drug Administration (FDA) approved a qualified health claim in 2005 stating that calcium supplements may reduce the risk of colorectal cancer and colorectal adenomas. However, the FDA has determined that there is little scientific evidence to support this claim (102366).
• Fetal bone mineralization. If calcium intakes are low during pregnancy, oral calcium seems to be beneficial for increasing fetal bone density. Details: With low dietary calcium intake (less than 562 mg elemental calcium daily) during pregnancy, calcium supplementation increases fetal bone mineralization and density. However, calcium supplementation does not offer any additional benefit if calcium intakes are adequate (3263,3264).
• Hypertension. Oral calcium seems to reduce blood pressure by a small amount. However, it is unclear if this reduction is clinically significant. Details: Many clinical trials and observational studies show that intake of calcium supplements or dietary calcium modestly reduces blood pressure in patients with or without hypertension, usually around 1-2 mmHg. Calcium seems to be more effective for certain subpopulations of patients, such as salt-sensitive people and patients with low baseline dietary calcium intake (945,972,974,976,984,1818,1819,1820,1821,6852)(13138,14406,38803,39063,39094,39221). Also, a meta-analysis of clinical research shows that calcium intake during pregnancy reduces systolic blood pressure in offspring by 1-2 mmHg (38852). However, a large-scale clinical trial in postmenopausal females shows that taking vitamin D (cholecalciferol) 400 IU daily in combination with elemental calcium 1000 mg daily does not lower blood pressure or reduce the risk of developing hypertension (16714). Additionally, a meta-analysis of 8 clinical trials shows that taking calcium in combination with vitamin D for up to 7 years has no effect on blood pressure (98861). The validity of this finding is limited by the poor methodological quality of the included studies. Some observational research suggests that calcium can reduce the risk for hypertension. Population research in females aged 45 years and older suggests that higher intake of calcium from both diet and supplement sources is linked to a lower risk of developing hypertension when compared to lower calcium intake (14265). In 2005, the US Food and Drug Administration (FDA) approved a qualified health claim stating that calcium supplements may reduce the risk of hypertension. However, the FDA has concluded that this claim is based on supporting, rather than conclusive, evidence (102367).
• Osteomalacia. Oral calcium seems to reverse osteomalacia caused by very low calcium intakes. Details: Osteomalacia is commonly caused by vitamin D deficiency; however, very low calcium intake can also lead to osteomalacia in children and adults. Calcium supplementation can reverse osteomalacia caused by calcium deficiency. Along with appropriate vitamin D supplementation, individuals at risk of osteomalacia need sufficient calcium intake (94819).
• Pre-eclampsia. Oral calcium seems to reduce the risk of pre-eclampsia in high risk pregnancies, especially if calcium intakes are low. Details: Although there is some conflicting evidence (971,38756), most clinical research shows that taking calcium orally 1-2 grams daily reduces pregnancy-related hypertension and pre-eclampsia (973,1833,8828,39043,39319,39426,96480). Calcium appears to reduce the risk of pre-eclampsia by about 50% when compared with placebo. One meta-analysis of 19 controlled trials involving over 29,000 pregnancies found that for every 19 females treated with calcium, one episode of pre-eclampsia would be avoided (96480). Calcium appears to have the greatest effect in individuals at high-risk of pre-eclampsia or with low calcium levels, and when taken at greater than or equal to 20 weeks of gestation (15029,38497,96480,99714). In 2005, the US Food and Drug Administration (FDA) approved a qualified health claim regarding the use of calcium supplements to reduce the risk of pregnancy-induced hypertension and pre-eclampsia. However, due to the limited and conflicting research available at that time, the FDA stated that this outcome was highly unlikely. Since then, large, high-quality clinical research has supported this finding. In fact, in 2016 the World Health Organization (WHO) released a recommendation to prescribe oral calcium supplementation 1.5-2 grams daily during pregnancies at high risk of pre-eclampsia if dietary calcium intakes are low, in order to prevent pre-eclampsia (97347).
• Rickets. Oral calcium seems to reverse rickets caused by very low calcium intakes. Details: Rickets is commonly caused be vitamin D deficiency; however, very low calcium intake can also lead to rickets. Calcium supplementation can reverse rickets caused by calcium deficiency (94819). A small clinical study in children with nutritional rickets shows that taking calcium 500-2000 mg daily for 24 weeks improves radiographically measured rickets caused by calcium deficiency. Rickets seems to improve more rapidly with calcium 1000 mg compared to calcium 500 mg. However, increasing the calcium dose to 2000 mg daily is not more beneficial than calcium 1000 mg daily (98904).
• Tooth retention. Oral calcium with vitamin D seems to help with tooth retention in the elderly population. Details: A clinical trial in the elderly population shows that taking calcium citrate malate 500 mg daily along with vitamin D3 (cholecalciferol) 700 IU daily orally for 3 years reduces the risk of tooth loss by about 52% when compared with placebo (8816).

POSSIBLY INEFFECTIVE

• Breast cancer. Oral calcium does not seem to be beneficial for breast cancer prevention. Details: Although some population research disagrees (15631,39041,95811,107237), most research shows that increased calcium intake is not associated with a reduced risk of breast cancer (15631,16715,98895,107236,107237). Subgroup analyses of population research suggest that calcium intake may reduce the risk of breast cancer in postmenopausal, but not pre-menopausal, adults (15631,107237). Another subgroup analysis in a large meta-analysis of population research also suggests that dietary intake may reduce estrogen receptor(ER)-negative breast cancer, but not ER-positive breast cancer (107236). However, most other research has not evaluated the effects of calcium supplementation or intake on breast cancer subtypes. The best evidence to date, from a large scale clinical trial (Women's Health Initiative), shows that taking vitamin D (cholecalciferol) 400 IU daily plus calcium 1000 mg daily for 7 years after menopause does not reduce the risk of developing invasive breast cancer at the end of the study and 5 years after the end of the intervention (16715,98895).
• Fractures. Although oral calcium prevents fractures in osteoporosis, most evidence shows that calcium does NOT prevent factures in people who do not have osteoporosis. See Osteoporosis discussion for more information on the use of calcium for this purpose. Details: The most recent and robust meta-analysis of clinical research shows that calcium supplementation with or without vitamin D is NOT associated with reduced fractures in older adults without osteoporosis (95822). A large-scale study in postmenopausal females aged 50-79 years suggests calcium 1000 mg plus vitamin D 400 IU daily for 7 years only modestly improves bone mineral density (BMD) and does not significantly reduce fracture risk. This lack of effect may have been due to low adherence to the treatment regimen. In those who were 80% adherent, the combination of calcium plus vitamin D reduced the risk of hip fracture by about 29% (14282). Also, some clinical research shows that taking calcium carbonate 1000 mg and vitamin D 400 IU for 5 years does not attenuate loss of height after menopause when compared with placebo (95810). Additional meta-analyses of clinical and observational evidence suggest that calcium supplementation is not associated with a reduced risk of vertebral or nonvertebral fractures, such as hip fractures (38589,38888,98895). Some other research has suggested that calcium in combination with vitamin D reduces fracture risk in older patients without osteoporosis (980,1836,8818,12930,12933,12952,38849,102145,107235); however, this research is confounded by a number of variables, including the presence of hormonal therapy and differing levels of fracture risk at baseline (1836,8818,95822). Conflicting findings on this topic might also be due to genetic differences in patient populations. A population analysis of the Women's Health Initiative study found that, in older females with the lowest genetic susceptibility to low bone mineral density (BMD), taking calcium with vitamin D is associated with a reduction in fracture risk. However, in females with a higher genetic susceptibility to low BMD, there is no association between supplementation and fracture risk. This might be because individuals with a lower susceptibility to low BMD are also more responsive to calcium and vitamin D supplementation (97357). As of April 2018, the U.S. Preventative Services Task Force (USPSTF) concludes that there is insufficient evidence to determine whether supplementing with vitamin D >400 IU daily along with calcium >1000 mg daily is safe and effective for preventing fractures in community dwelling adults without vitamin D deficiency, osteoporosis, or a history of fracture. USPSTF recommends against supplementing with calcium 1000 mg daily or less along with vitamin D 400 IU daily or less for preventing primary fractures in community-dwelling postmenopausal females (95695).
• Obesity. Oral calcium does not seem to improve weight loss. Details: Observational research has found that adults and children with low calcium intake are more likely to gain weight, have a higher body mass index (BMI), and be overweight or obese when compared to people with high calcium intake (12124,12125,12126,12127,14265). Additional observational research has found that increasing calcium intake is associated with weight loss in females; the results in males have been conflicting (12127,15602,15603). Despite these findings from observational research and a few small clinical studies (12128,15397,14438,98905), most clinical research has found that increased calcium intake does not increase weight loss (12052,13138,15396,15399,38985,39004,97356). The most recent meta-analysis of 20 clinical studies shows that daily dietary and supplemental calcium intake that meets the dietary reference intake (DRI) of 1000 mg or more daily does not increase weight loss in overweight individuals or patients with obesity when compared with intake below the DRI (95813). An older meta-analysis of 13 clinical trials also shows that increased dietary and supplemental calcium intake does not increase weight loss (15605).
• Overall mortality. Oral calcium does not seem to reduce overall mortality. Details: While some population research has found that calcium taken in combination with vitamin D in older females is associated with a lower risk of death (97353), most evidence shows that calcium, with or without vitamin D, has no effect on all-cause mortality (93533,97308).

INEFFECTIVE

• Cardiovascular disease (CVD). Oral calcium does not reduce the risk of developing CVD and may actually increase risk in some patients. Details: Clinical research shows that calcium does not decrease CVD risk. Several separate meta-analyses of clinical and population research involving over 50,000 patients show that taking calcium 600-1200 mg daily for up to 7 years does not reduce the risk of CVD-related outcomes, including stroke and myocardial infarction, cardiovascular death, or overall mortality (39018,91350,92994,93533,97308,98902,107231,107233). No association was found between total dietary or supplemental calcium intake with or without vitamin D and the risk of CVD or mortality (91350,93533,97308). In fact, some population and clinical research has found that when calcium is used alone or with vitamin D, there is an INCREASED risk of CVD and coronary heart disease (38077,107233). However, other clinical research disagrees (93533). One meta-analysis of high-quality randomized controlled trials shows that taking calcium for 2-7 years increases the risk of CVD and coronary heart disease by 1.1-1.2 times when compared with control. However, the majority of the included research evaluated postmenopausal females and it is unclear if this finding is applicable to other populations (107233).
• Chemotherapy-induced peripheral neuropathy. Intravenous calcium does not prevent nerve pain in patients given oxaliplatin. Oral calcium has not been evaluated for this purpose. Details: While pooled analyses of cohort studies and randomized controlled trials suggest that calcium and magnesium infusion decreases the incidence of oxaliplatin-induced neurotoxicity, a meta-analysis of only randomized controlled trials shows that the infusion has no effect in preventing neurotoxicity (90028,90029,90031). Additionally, clinical trials show that administering calcium gluconate 1 gram with magnesium sulfate 1 gram intravenously immediately before, or before and after, the administration of a single oxaliplatin cycle (90005), or over the entire 6-cycle course of oxaliplatin, does not improve symptoms of neurotoxicity when compared with placebo (96474).
• Myocardial infarction (MI). Oral calcium does not prevent MI. When taken in the absence of vitamin D, oral calcium may increase the risk of MI. Details: Population research has found that increased dietary intake of calcium is associated with a decreased risk of MI (91350). However, a 2010 meta-analysis of clinical research shows that taking calcium at a dose of at least 500 mg daily is associated with an approximate 30% INCREASE in the risk of MI in patients over the age of 40. According to this analysis, one additional case of MI will occur for every 69 patients that take calcium for 5 years (17482). A more recent meta-analysis of high-quality randomized controlled trials shows that taking calcium for 2-7 years increases the risk of MI by 1.2 times when compared with control. However, the majority of the included research studied postmenopausal females and it is unclear if this finding is applicable to other populations (107233) In contrast, other meta-analyses of clinical research have shown that taking calcium for up to 7 years is NOT associated with an increased risk of MI, including a meta-analysis that only included postmenopausal females (93533,107231). Reasons for these discrepancies are not entirely clear. It may relate to whether calcium is taken as monotherapy or in combination with vitamin D. When taken with vitamin D, which is commonly recommended, calcium supplementation does not appear to be associated with an increased risk of MI in postmenopausal females (93533). Also, the association between calcium supplementation and MI risk may be influenced by the amount of calcium consumed as part of the diet. Supplementation with calcium may be associated with an increased risk of MI in people with dietary calcium intake above 805 mg daily, but not in those with dietary calcium intake below 805 mg daily (17482)

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Alcohol use disorder. It is unclear if oral calcium is beneficial for alcohol use disorder. Details: Preliminary clinical research shows that taking calcium carbonate 800 mg and vitamin D 200 IU orally daily for 14 days modestly reduces alcohol craving scores and withdrawal scores when compared with placebo in adults with alcohol dependence that are undergoing withdrawal. Taking calcium carbonate did not reduce the need for diazepam; however, the study may have been inadequately powered to detect a difference between groups (107234).
• Atherosclerosis. It is unclear if oral calcium is beneficial for atherosclerosis. Details: A population study has found that taking calcium 1.2 grams daily for 3 years has no effect on carotid intima thickness or carotid atherosclerosis incidence. A total calcium intake (dietary and supplemental) of at least 1794 mg daily in older females may be associated with a decreased risk of carotid atherosclerosis when compared with a total calcium intake below 1010 mg daily (97351).
• Autism spectrum disorder. It is unclear if oral calcium during pregnancy is beneficial for reducing the odds of autism spectrum disorder in the offspring. Details: A small observational study found that calcium supplementation during pregnancy is associated with a 52% reduced odds of an autism spectrum disorder in the offspring (98900).
• Cancer. Oral calcium alone does not seem to prevent cancer. It is unclear if oral calcium with vitamin D is beneficial for preventing cancer. Details: Taking calcium alone does not seem to significantly reduce the risk of cancer (12118,15629). The role of calcium in cancer prevention when taken along with vitamin D is controversial, as conflicting results exist. One clinical trial shows that healthy postmenopausal females who take supplemental calcium 1400-1500 mg daily plus vitamin D3 (cholecalciferol) 1100 IU daily have a 60% lower relative risk for developing cancer of any type. Approximately 25 postmenopausal females would need to take this combination for 4 years to prevent one occurrence of cancer (15629). However, a more recent clinical study shows that healthy postmenopausal females who take supplemental calcium 1500 mg daily plus vitamin D3 (cholecalciferol) 2000 IU daily do not have a reduced risk of cancer at 4 years (93943). Reasons for the disparate results are not entirely clear. The discrepancies do not appear to be related to baseline vitamin D levels or different study populations. It is possible that, given the 10-year time lapse between the two publications, the discrepancies result from differences in cancer detection capability. Also, since cancer risk was a secondary outcome measure in the earlier study and a primary outcome measure in the more recent study, it is possible that the discrepancies result from differences in statistical methodologies. The effect of vitamin D and calcium on cancer risk in males and younger patients is not known. There is also interest in using calcium for reducing the risk of hematological malignancies. An analysis of the Women's Health Initiative study shows that taking calcium 1000 mg daily in combination with vitamin D3 400 IU for up to 10 years is associated with a 20% reduction in the risk of hematologic malignancies when compared with placebo. However, no effect on hematologic malignancy related mortality was seen (97354).
• Depression. It is unclear if oral calcium is beneficial for depression prevention. Details: Population research has found no association between a higher dietary intake of calcium and the risk of depression when compared with a lower dietary intake of calcium (96480).
• Diabetes. It is unclear if oral calcium is beneficial for type 2 diabetes prevention. Details: Some population research has found that a higher intake of calcium from diet or supplements, alone or in combination with vitamin D, is associated with a lower risk of developing type 2 diabetes when compared with lower calcium intake (14265,16713,96473). However, population research is often limited by confounding variables. For example, one analysis found that any beneficial effect might be influenced by concomitant magnesium intake (96473). Furthermore, other population research has found that serum calcium levels higher than 9.6 mg/dL are associated with greater risk of developing diabetes in Chinese adults with osteoporosis. This study is limited because it was not determined whether increased serum calcium was due to increased calcium intake or another factor such as parathyroid function (95815).
• Dysmenorrhea. It is unclear if oral calcium is beneficial for reducing pain associated with dysmenorrhea. Details: Clinical research shows that taking calcium carbonate 1000 mg with vitamin D 5000 IU daily for three menstrual cycles does not reduce pain when compared with placebo in patients with primary dysmenorrhea (95821). However, calcium carbonate 1000 mg taken alone seems to reduce pain when compared with placebo.
• Endometrial cancer. It is unclear if oral calcium is beneficial for endometrial cancer prevention. Details: A meta-analysis of population research suggests that calcium supplements may reduce the risk of endometrial cancer, but dietary calcium does not seem to have any effect (38893).
• Fall prevention. It is unclear if oral calcium with vitamin D is beneficial for preventing falls. Details: Research suggests that calcium in combination with vitamin D, but not calcium alone, might prevent falls by decreasing body sway and normalizing systolic blood pressure (6362,11939,39038). Some experts think the combination of calcium and vitamin D may be important (11916). Preliminary clinical research in adults residing in a health care facility shows that taking vitamin D supplements while increasing dietary calcium and protein for 2 years reduces falls by 11% when compared with standard diets. Intervention diets were supplemented with milk, yogurt, and cheese to provide calcium 1142 mg and protein 69 grams daily (107235). There might also be different effects in females compared to males. In one study, females aged 65 years or older who took vitamin D 700 IU plus calcium citrate 500 mg daily over a 3-year period had a 46% lower risk of falling. However, this combination did not decrease falls in males (14291).
• Fluorosis. Oral calcium has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Taking calcium orally, in combination with ascorbic acid (vitamin C) and vitamin D, seems to be effective for reducing excessive fluoride levels in children and improving symptoms of fluorosis in children aged 6-12 years (990).
• Heart failure. It is unclear if oral calcium in combination with vitamin D is beneficial for preventing heart failure. Details: Based on a secondary analysis of a large-scale clinical trial (Women's Health Initiative), taking calcium 1000 mg with vitamin D 400 IU daily does not reduce the risk of heart failure in the overall population or in individuals at high risk. However, in a subgroup of postmenopausal females without risk factors for heart failure, calcium and vitamin D supplementation might reduce the risk of developing heart failure by about 37% (97307).
• Hypercholesterolemia. It is unclear if oral calcium is beneficial for hypercholesterolemia. Details: Some evidence shows that taking calcium carbonate 400 mg three times daily reduces low-density lipoprotein (LDL) cholesterol levels by 4% and increases high-density lipoprotein (HDL) cholesterol levels by 4% after 6 weeks of treatment when used in combination with a low-fat diet (American Heart Association Step 1) (2557). In contrast, a study in females with dyslipidemia shows that taking calcium 800 mg daily for 2 years might INCREASE total cholesterol levels by about 12 mg/dL when compared with placebo. This same study showed an association between calcium supplementation and an increase in total cholesterol levels and carotid intimal thickness in postmenopausal females, but not premenopausal females (97350). A recent meta-analysis of randomized controlled trials which included both healthy patients and patients with dyslipidemia shows that taking calcium 500-2000 mg daily and vitamin D 200-7142 IU daily modestly improves HDL cholesterol and triglyceride levels, but not LDL cholesterol levels, when compared with placebo. Subgroup analyses suggest that calcium and vitamin D supplementation is more effective in patients with dyslipidemia at baseline. It is unclear if this effect is due to calcium, vitamin D, or the combination (107227). However, other research shows that taking a specific supplement containing calcium 600 mg plus vitamin D 200 IU (Caltrate 600 D, Wyeth Consumer Healthcare Inc.) twice daily in combination with calorie restriction does not reduce total or LDL cholesterol levels when compared with placebo (15601).
• Lead toxicity. It is unclear if oral calcium is beneficial for reducing blood levels of lead. Details: Lead is mobilized along with calcium from bone during pregnancy and lactation, resulting in increased serum concentrations of lead. One clinical study suggests that calcium supplementation does not significantly decrease these elevated lead concentrations (1586). However, another clinical study suggests that taking calcium reduces blood lead levels by 11% when compared with placebo, with greatest effects observed in those with high baseline levels of lead (38957).
• Lyme disease. Although there is interest in using oral calcium for Lyme disease, there is insufficient reliable information about the clinical effects of calcium for this condition.
• Metabolic syndrome. It is unclear if oral calcium alone or with vitamin D is beneficial for metabolic syndrome prevention. Details: Population research has found that a higher intake of calcium from diet and supplements alone, or in combination with vitamin D, is associated with a lower risk of developing metabolic syndrome when compared with lower calcium intake (14265,16713).
• Nephrotic syndrome. It is unclear if oral calcium with vitamin D is beneficial for preventing nephrotic syndrome. Details: Clinical research shows that taking calcium 500-1000 mg daily for 3 months in combination with vitamin D3 60,000 IU daily or weekly for 4 weeks has no effect on bone mineral density or the risk of relapse in children with steroid-sensitive nephrotic syndrome (97355).
• Nonmelanoma skin cancer. It is unclear if oral calcium is beneficial for preventing keratinocyte carcinomas. Details: In middle aged and older adults recently diagnosed with a colorectal adenoma, clinical research shows that taking calcium 1200 mg daily as calcium carbonate for 3-5 years does not reduce the incidence of keratinocyte cancer when compared with placebo over a median of 8 years. A sub-group analysis shows that taking calcium alone or with vitamin D3 1000 IU daily reduced the risk of invasive cutaneous squamous cell carcinoma by a moderate amount, but had no effect on the risk of basal cell carcinoma (104622).
• Oral mucositis. When used in combination with fluoride treatments, a calcium phosphate mouth rinse seems to prevent and reduce mucositis-related pain in patients undergoing hematopoietic stem cell transplantation (HSCT). Details: A small clinical study in patients undergoing HSCT shows that using a particular mouth rinse (Caphosol, EUSA Pharma) containing calcium phosphate, in combination with fluoride treatments, reduces days of mucositis, the duration of pain, and the dose and days of morphine used when compared with placebo and fluoride treatment (38611).
• Ovarian cancer. It is unclear if oral calcium is beneficial for ovarian cancer prevention. Details: An older meta-analysis of 12 cohort studies found that dietary calcium intake is not associated with a reduced risk of ovarian cancer (38792). However, a more recent pooled analysis of 15 cohort and case-control studies has found that the highest intake of dietary or dairy calcium is associated with a 20% lower risk of ovarian cancer when compared to the lowest intake (97349).
• Postpartum depression. It is unclear if oral calcium is beneficial for reducing postpartum depression risk. Details: Preliminary clinical research shows that taking calcium 2 grams daily beginning at 11-21 weeks gestation reduces depression at 12 weeks postpartum when compared with placebo. However, no benefit is seen at 6 weeks postpartum (39447).
• Pregnancy-related leg cramps. It is unclear if oral calcium is beneficial for preventing leg cramps during pregnancy. Details: A small clinical study shows that taking calcium 1 gram twice daily (as a mixture of salts) for 2 weeks can reduce pregnancy-related leg cramps during the second half of pregnancy when compared with no treatment (2567).
• Prostate cancer. It is unclear if oral calcium is beneficial for prostate cancer prevention. Details: Some clinical research shows that taking calcium 1200 mg daily might decrease the risk of developing prostate cancer (14133). However, some epidemiological research suggests that consuming very high doses of calcium, over 2000 mg daily, might actually increase the risk of developing prostate cancer (14134). Some epidemiological research also suggests that doses greater than 1500 mg daily increase the risk of poorly differentiated, clinically advanced, and fatal prostate cancer (14132). Consumption of dairy products has also been weakly linked to a modest increase in risk of prostate cancer (98894). However, contradictory research suggests that there is no association between dietary intake of calcium and overall risk of prostate cancer (14131,14132,104630).
• Stroke. It is unclear if oral calcium is beneficial for stroke prevention. Details: Some population research has found that increasing dietary calcium intake is associated with a decreased risk of ischemic stroke (4822,38678). However, other population research has found that increasing dietary calcium intake is not associated with a decreased risk of stroke (91350). One meta-analysis of high-quality randomized controlled trials shows that taking calcium for 2-7 years does not affect the risk of stroke when compared with control. However, the majority of the included research evaluated postmenopausal females, and it is unclear if this finding is applicable to other populations (107233).
• Vertigo. Oral calcium with vitamin D might reduce positional vertigo; the effect of calcium when used alone is unclear. Details: A large clinical study in adults with recurrent benign paroxysmal positional vertigo shows that taking calcium 500 mg and vitamin D 400 IU twice daily for one year reduces annual recurrence of vertigo by 27% when compared with no treatment. The number needed to treat to prevent vertigo was 3.7 (103681). It is unclear if this benefit is due to vitamin D, calcium, or the combination. More evidence is needed to rate calcium for these uses.

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LIKELY EFFECTIVE

• Delayed sleep phase syndrome (DSPS). Oral melatonin shortens the time needed to fall asleep in children and adults with DSPS. Details: Most clinical research shows that taking melatonin orally reduces the length of time needed to fall asleep and advances sleep onset time in young adults and children with DSPS (8244,12226,15005,62714,62792,63055,88288,88290,89509). In adults, 0.3-5 mg daily for up to 9 months has been used (8244,62714,62792,63055,88290,89509). In children, 1-6 mg before bedtime for up to one month has been used (62714,62792,89509). In addition to improving sleep, melatonin also improves measures of quality of life such as mental health, vitality, and bodily pain in young adults with DSPS (8244,12226,15005). However, relapse to pre-treatment sleeping patterns seems to occur within one year after stopping supplementation (63048).
• Non-24-hour sleep wake disorder. Oral melatonin improves non-24-hour sleep wake disorder in blind children and adults. Details: Taking oral melatonin 0.5-4 mg daily in children and 0.5-10 mg daily in adults for up to 6 years helps improve circadian rhythm sleep disorders in blind children and adults (1082,1744,1749,6585,62346,62350).

POSSIBLY EFFECTIVE

• Beta blocker-induced insomnia. Oral melatonin seems to improve sleep in patients with insomnia related to the use of beta-blockers. Details: Beta-blockers such as atenolol and propranolol seem to decrease endogenous melatonin levels (1780). This might result in insomnia as a side effect. Clinical and preclinical research shows that taking a melatonin supplement might decrease the insomnia caused by beta-blockers (1062,89502). Taking melatonin 5 mg at night after taking atenolol 100 mg appears to attenuate the changes in sleep onset latency, total wake time, and wakefulness after sleep onset when compared with taking atenolol 100 mg alone (1062). Also, in patients taking atenolol or metoprolol, taking melatonin 2.5 mg one hour before bedtime for 20-28 days increases total sleep time by 13-37 minutes and decreases sleep latency by 8-14 minutes when compared with placebo (89502).
• Cancer. In patients with various types of cancer, most research shows that oral or combined intramuscular/oral melatonin in combination with chemotherapy or other treatments seems to improve tumor regression and survival rates. Details: There is some evidence that taking combined high-dose melatonin with conventional chemotherapy or with interleukin-2 (IL-2) might improve tumor regression rate in patients with breast, lung, kidney, liver, pancreatic, stomach, or colon cancer (1692,5854,5855,5857,7040,7043,8268,62407,62844). Melatonin plus chemotherapy in patients with metastatic solid tumors seems to increase the regression rate and one-year survival rate by about 40% to 50% when compared with chemotherapy alone (7040,62407,62844,89504). The addition of melatonin also seems to help reduce chemotherapy toxicities, including hematologic complications, cachexia, asthenia, and neuropathy (8268,62844,89504). There is also some preliminary evidence that melatonin alone, orally or intramuscularly, might improve stabilization rate and possibly one-year survival rate in patients with resistant or untreatable neoplasms of the lung, liver, pancreas, colon, breast, or brain (1080,1688,1693,2566). Also, when used in combination with radiotherapy, high-dose melatonin seems to increase the survival time and percent survival in patients with brain glioblastomas when compared with radiotherapy alone (62991). However, high-dose melatonin treatment does not seem to improve the survival of patients with brain metastases who receive radiation therapy (62455). Melatonin 10-40 mg daily has been used in most clinical trials (1080,1692,1693,2566,5854,5855,5857,7040,7043,8268)(62455,62844,62991,89504). In one study, melatonin 20 mg intramuscularly daily for 2 months, followed by oral melatonin 10 mg daily as maintenance, was used (1688). The effect of melatonin on quality of life and sleep quality in patients with cancer has also been investigated. A meta-analysis of six clinical trials shows that taking melatonin 20 mg daily does not improve sleep quality or quality of life when compared with a control, usually placebo. The duration of studies varied widely; from a period of 7 days or until death. However, there was a modest effect of melatonin on symptoms of depression in patients taking it for at least 14 days or those who underwent surgery (109697).
• Emergence delirium. Oral melatonin seems to be beneficial for reducing sevoflurane-induced agitation in children. It is unclear if oral melatonin is beneficial for adults undergoing surgery. Details: A meta-analysis of clinical research in perioperative adults shows that taking melatonin 3-5 mg or ramelteon 8 mg orally daily for 1-7 days reduces the risk of emergence delirium by 59% when compared with placebo or no treatment. However, the validity of these results is limited by high heterogeneity (112053). Clinical research in children aged 3-9 years shows that taking melatonin 0.3 mg/kg as part of a multimodal anxiolytic strategy reduces the incidence of sevoflurane-associated emergence delirium when compared with placebo or midazolam 0.3 mg/kg. Emergence delirium occurred in 27% of those children given melatonin, compared with 50% of those given placebo and 56% of those given midazolam (106292). In addition, a meta-analysis of three small clinical studies in children aged 2-9 years shows that taking melatonin 0.05-0.5 mg/kg 40-45 minutes prior to sevoflurane reduces the incidence of agitation when compared with placebo, with inconclusive outcomes when compared with midazolam and dexmedetomidine. A sub-group analysis indicates that doses of melatonin 0.2 mg/kg or greater may be most effective (97440). However, taking melatonin 0.5 mg/kg before surgery is 55% less effective than intranasal dexmedetomidine 2 mg/kg for reducing the incidence of sevoflurane-associated emergence delirium (109701).
• Hypertension. Oral controlled-release melatonin seems to reduce blood pressure by a small amount in patients with hypertension. Immediate-release melatonin may not have the same effect. Details: Controlled-release melatonin 2-24 mg, taken before bedtime for up to 4 weeks, seems to lower systolic blood pressure (SBP) by 4-6 mmHg and diastolic blood pressure (DBP) by about 4 mmHg in individuals with essential hypertension or high blood pressure at nighttime (62359,62416,62441,62826,108947). Some evidence shows that immediate-release melatonin does not have this effect (62826). Some evidence also suggests that melatonin seems to slightly reduce blood pressure in patients without hypertension, but to a lesser degree (103689). However, a very small clinical study in healthy young adults consuming a high sodium diet (6900 mg daily) shows that taking melatonin 10 mg before bedtime for 10 days decreases nighttime SBP but does not improve nighttime DBP, daytime SBP or DBP, 24-hour SBP or DBP, or nocturnal dipping of SBP or DBP when compared with placebo (112442).
• Insomnia. In patents with insomnia, oral melatonin seems to shorten the time it takes to fall asleep by about 7-12 minutes, although the effect on the amount of time asleep is inconclusive. Melatonin is more likely to be beneficial in older adults or people with certain comorbidities. Details: Short-term melatonin treatment appears to modestly reduce the time it takes to fall asleep (sleep latency) in otherwise healthy adults with insomnia. This reduction in sleep latency appears to amount to only about 7-12 minutes and might not be considered clinically relevant. Melatonin does not appear to improve sleep efficiency and may only increase total sleep time by about 8 minutes (15005,88290). Despite lack of substantial improvements in objective measures, some patients report minor improvement in subjective feelings of sleep quality (1070,1083,12226,88290). In children aged 6-12 years with insomnia due to delayed onset of sleep, melatonin 5 mg or 0.05-0.15 mg/kg at bedtime for up to 4 weeks seems to shorten the time that it takes to fall asleep and increases the duration of sleep (9708,62345,62770). More evidence is needed on the long-term effects of melatonin for insomnia. Some evidence shows that taking oral melatonin might be most beneficial for insomnia in elderly patients who could be melatonin deficient (1072,1729,1738,1754,7081,15005,62357,62465,62472,62613)(62776,62789). Taking sustained-release melatonin preparations 2 mg daily seems to improve sleep maintenance and sleep quality in elderly individuals (1738,1754,62465,62472,62613,62776), while immediate-release preparations seem to decrease sleep latency (1738,63041). In these clinical trials, controlled-release, fast-release, or slow-release melatonin 2-3 mg before bedtime for up to 29 weeks has been used (1072,1738,1754,7081,62357,62465,62472,62613,62776,62789). However, using a melatonin patch placed on the gums does not improve sleep parameters in elderly patients with insomnia (63062). Some research shows that taking melatonin when taken either alone or in combination with other sleep aids such as bright-light treatment seems to be beneficial for insomnia in patients with certain comorbid conditions. Taking melatonin 2-12 mg for up to 4 weeks has been used to improve insomnia in patients with depression (1053,1729), schizophrenia (8245,62452), bipolar disorder (62140), asthma (62375), cystic fibrosis (62708), hospitalization (9709,106295), and insomnia termed "ICU syndrome", which refers to sleep disturbances while in the intensive care unit (8240). Insomnia is also improved in children aged 3-12 years with epilepsy taking 6-9 mg of melatonin before bedtime for 4 weeks (62394,99342) and quality of sleep is modestly improved in adults with epilepsy taking 3 mg before bedtime for 8 weeks (110299). There is also evidence that melatonin can improve total sleep time and sleep-onset latency in children with tuberous sclerosis (1747), autism spectrum disorders (1056,62811,88286,96318,106293,110290), developmental disabilities (9707), and neurodevelopmental disorders (21819,62143,88283). It also appears to decrease sleep latency and increase sleep time in adults and children with intellectual disabilities, with or without epilepsy (62373,62561). While some evidence shows that fast-release melatonin is more effective for improving the time to fall asleep in children with sleep-wake cycle disturbances and neurodevelopmental disabilities, it is unclear if controlled-release melatonin provides any additional benefits in this population (62143,95746). However, there is conflicting evidence regarding the effects of melatonin in patients with insomnia and comorbid conditions such as Alzheimer disease or dementia. Some clinical research shows that taking melatonin 3-5 mg before bedtime for up to 10 weeks, either alone or in combination with bright-light treatment, improves impaired sleep related to Alzheimer disease or dementia (1729,62474,63059). But not all research agrees. Meta-analyses of several clinical studies show that taking melatonin 3-10 mg daily improves subjective sleep quality, but not objective outcomes such as number of awakenings at night and sleep efficiency in these patients. Also, immediate-release melatonin 2.5-10 mg or prolonged-release melatonin 1.5-2.5 mg for 10 days to 24 weeks shows inconsistent effects on total sleep time at night in patients with Alzheimer disease (96319,96320). There is also mixed evidence regarding the effects of melatonin in patients with Parkinson disease. Some subjective outcomes such as sleep quality seem to improve. However, the improvement might not be clinically significant, and objective outcomes such as sleep efficiency and total sleep time at night do not seem to improve (62403,62454,62829,96320). Melatonin has also been evaluated in postoperative patients and patients with traumatic brain injury (TBI). Taking melatonin before bed does not improve sleep quality soon after tracheostomy, laparoscopic cholecystectomy, or total knee arthroplasty (62439,62552,99343,100255) or 2-6 weeks after total joint arthroplasty (106305). In adults with TBI, one clinical study shows that taking prolonged-release melatonin (Circadin, Sigma Pharmaceuticals) 2 mg two hours prior to bedtime for 4 weeks improves sleep quality, efficiency, and fatigue when compared with placebo. However, melatonin did not improve sleep onset latency or daytime sleepiness. There appears to be no association between TBI severity and the effect of treatment (96317). There is mixed evidence regarding the effect of melatonin in patients undergoing hemodialysis. Some evidence shows that taking melatonin (Pharma Nord) 3 mg before bed for 6 weeks reduces time needed to fall asleep, improves sleep efficiency, and increases actual sleep time when compared with placebo (62521). Other clinical research in patients undergoing hemodialysis shows that taking immediate-release melatonin 3 mg (Puritans Pride, USA) for 3 months modestly improves various sleep measures when compared with placebo. After treatment, 63.0% of those taking melatonin had no insomnia compared with 7.7% of those taking placebo (110291). However, other evidence shows that taking immediate-release melatonin (Pharma Nord) 3 mg nightly for 12 months does not improve quality of life or sleep efficiency in these patients, indicating that melatonin may not improve sleep long-term (89501). Finally, limited evidence shows that melatonin does not improve insomnia in patients with substance use disorders (97441).
• Jet lag. Taking oral melatonin 2-3 mg daily while travelling seems to improve alertness and reduce daytime sleepiness in people with jet lag. It is unclear if it improves sleep efficiency in this population. Higher doses might have a hypnotic effect. Details: Most research shows that melatonin can modestly improve certain symptoms of jet lag such as alertness and psychomotor performance. Melatonin also seems to improve, to a lesser extent, other jet lag symptoms such as daytime sleepiness and fatigue (12226). Melatonin might not be effective for decreasing the time to fall asleep (sleep latency) or sleep efficiency in patients with jet lag (6496,14283), although some research shows a beneficial effect of melatonin on these outcomes (62364). Doses between 0.5-5 mg appear to be equally effective. Although doses of up to 8 mg have been used, doses greater than 5 mg do not seem to be more effective and seem to produce a greater hypnotic effect. Travelers traveling eastward through five or more time zones may find 2-3 mg of melatonin, either slow-release or fast-release, to be useful when taken at local bedtime on the day of arrival and for 2-5 nights thereafter. Taking melatonin in advance of travel does not help prevent jet lag. The usefulness of melatonin for westward travel or over fewer time zones is less clear, although some evidence suggests that slow-release formulations are less effective than fast-release preparations (1049,1077,1079,1085,1722,8273,9181,9750,62706).
• Migraine headache. Oral melatonin 3-4 mg seems to prevent migraines when used prophylactically. It is unclear if oral melatonin is beneficial for treating migraine. Details: Melatonin production might be altered in people with migraine headache (6712,96316). Meta-analyses and individual clinical studies in adults have shown that taking melatonin modestly reduces migraine severity, duration, and frequency, and increases the likelihood of a 50% reduction in the baseline frequency of migraine, when compared with placebo or baseline. Immediate- or prolonged-release melatonin (occasionally as Circadin, Sigma Pharmaceuticals) in doses of 3-4 mg each evening for up to 6 months have been used in these studies (12149,96316,97438,103486,110286). Meta-analyses have included two or three individual clinical trials (103486,110286). One meta-analysis shows that taking melatonin reduces the frequency of migraine days by about 1.7 (103486). An additional meta-analysis in adults with migraines shows that taking melatonin modestly reduces the use of analgesic medications from baseline, when compared with placebo (110286). In contrast, other clinical research shows that taking extended-release melatonin (Circadin, Neurim Pharmaceuticals Ltd.) 2 mg nightly for 8 weeks does not reduce migraine attack frequency when compared with placebo (62784). Some clinical research also shows that melatonin is as effective as standard treatment for migraine prevention. Some research shows that taking melatonin 3 mg daily for 12 weeks is as effective as amitriptyline 25 mg in reducing migraine frequency, intensity, and duration, as well as reducing analgesic use (96316). A meta-analysis of two clinical trials shows that taking melatonin 3 mg each evening for 8-12 weeks is as effective as standard treatment; however, only one study each compared melatonin with amitriptyline (96316) and valproate (110286). More research comparing melatonin with standard treatments is needed. Melatonin has also been investigated in children. Preliminary clinical research in children 5-15 years of age with migraine headache shows that taking melatonin 0.3 mg/kg daily for 90 days reduces migraine frequency, severity, and duration, and decreases analgesic use when compared to baseline (97446). Some research also suggests that melatonin might help to TREAT migraine headache in children and adolescents aged 9-17 years. Preliminary clinical research shows that taking melatonin 1-8 mg reduces pain by a small amount 2-4 hours later. The higher doses of 2 mg for children weighing less than 40 kg and 8 mg for children weighing at least 40 kg seemed to have the greatest benefit (103487). This study is limited by the lack of a comparator group and a very high drop-out rate.
• Pre-procedural anxiety. Most research shows that oral or sublingual melatonin reduces preoperative anxiety in adults. The benefit in children is unclear. Details: A meta-analysis of 18 clinical studies in adults shows that taking oral or sublingual melatonin 3-10 mg or 0.05-0.4 mg/kg 20-120 minutes prior to surgery reduces preoperative anxiety by an average of 12 points on a 100-point visual analogue scale when compared with placebo. It also reduces postoperative anxiety by about 5 points when compared with placebo. Furthermore, a meta-analysis of 7 small clinical trials suggests that melatonin is comparable to benzodiazepines such as midazolam, oxazepam, or alprazolam for reducing preoperative anxiety (105005). In some cases, melatonin might also be preferable to benzodiazepines because it does not cause anterograde amnesia, respiratory depression, or impairment of cognitive and psychomotor skills (88299,99337). However, research in children is conflicting. One small clinical study in children aged 2-8 years preparing to undergo outpatient elective surgery shows that taking melatonin 0.05-0.4 mg/kg 45 minutes before anesthesia is less effective than midazolam 0.5 mg/kg for reducing anxiety during separation from parents and when putting on the anesthesia mask (62601). In contrast, another small clinical study in children aged 2-5 years undergoing minor elective surgery shows that taking oral melatonin 0.25-0.5 mg/kg 1 hour before anesthesia is similar to midazolam 0.25-0.5 mg/kg for reducing anxiety when separating from parents and when putting on the anesthesia mask (62399). A third study in children aged 3-8 years found no differences between melatonin 0.3 mg/kg, midazolam 0.3 mg/kg, and placebo for reducing preoperative anxiety (106292).
• Pre-procedural sedation. Oral melatonin might reduce the sedative dose required to achieve adequate sedation in children. It is unclear if oral melatonin is beneficial for this purpose in adults. Details: A clinical study in children aged 5-14 years undergoing surgery shows that oral melatonin 0.5 mg/kg reduces the propofol dose required for adequate sedation by 0.77 mg/kg when compared with midazolam 0.5 mg/kg (97444). However, taking melatonin 0.5 mg/kg 45 minutes before surgery is less effective than intranasal dexmedetomidine 2 mg/kg for successful mask acceptance and parental separation (109701). A meta-analysis of clinical and observational studies in children undergoing non-operative procedures, such as electroencephalogram (EEG) and magnetic resonance imaging (MRI), suggests that enteral or parenteral melatonin is no better for adequate sedation than sleep deprivation or chloral hydrate (105884). This finding is limited by imprecision, inconsistency, and a high risk of bias. A small clinical study in adults undergoing total abdominal hysterectomy shows that taking extended-release melatonin 5 mg, 90 minutes before surgery, decreases the use of midazolam for sedation during surgery when compared with placebo (108945). However, the validity of this finding is unclear, as 0% of patients in the melatonin group required midazolam, compared with 100% of patients in the placebo group. In adults undergoing lower extremity orthopedic surgery with spinal anesthesia, a small study shows that giving melatonin 10 mg orally the night before surgery, followed by 10 mg 2 hours prior to surgery, increases the sedation score when compared with placebo (108951).
• Sunburn. Most research shows that topical melatonin seems to protect against erythema from ultraviolet (UV) light exposure. Details: When applied prior to UV light exposure, a gel containing melatonin 0.05% to 2.5% seems to significantly decrease erythema (1066,1768,1769). In one study, topically applied melatonin in combination with vitamin E 2% and/or vitamin C 5%, was modestly photoprotective when used prior to UV exposure, but had no effect when used during or after UV exposure (4713,4714). Other preliminary clinical research shows that applying a cream containing melatonin 12.5% prior to sun exposure reduces erythema in adults with high sun reactivity, but not in those with mild to moderate sun reactivity. Creams containing melatonin 0.5% or 2.5% did not reduce erythema in any skin types when compared with placebo (97443). The differences in these findings may be related to the different topical formulations used.
• Temporomandibular disorders (TMD). Oral melatonin seems to moderately reduce pain in females with TMD. Details: Clinical research shows that taking melatonin 5 mg at bedtime for 4 weeks reduces pain by 44% and increases the ability to withstand pain by 39% when compared with placebo in females with TMD. This results in reduced analgesic use and improved sleep quality (89508).
• Thrombocytopenia. Oral melatonin seems to improve and prevent thrombocytopenia associated with cancer, cancer treatment, and other disorders. Details: Clinical research shows that taking melatonin can improve thrombocytopenia associated with cancer, cancer treatment, and other disorders. Melatonin 20-40 mg daily beginning up to 7 days before chemotherapy and continuing for up to four chemotherapy cycles or until disease progression has been used (1694,1695,1696,1697,2564,8268).

POSSIBLY INEFFECTIVE

• Athletic performance. Most research suggests that oral melatonin does not improve athletic performance or physical strength. Details: Taking melatonin 6 mg one hour prior to heavy resistance exercise does not seem to improve maximal strength or maximal jumping ability (62424). Also, taking melatonin 5 mg at night does not appear to improve exercise performance the following morning in healthy athletes (62179). Furthermore, taking melatonin 5 mg 15 minutes prior to exercise does not appear to impact endurance during a cycling trial when compared with placebo (99338). However, some research disagrees. One small clinical trial in professional soccer players shows that taking melatonin 5 mg daily during a six-day training schedule modestly attenuates deterioration in physical performance, such as jumping, agility, and sprints, when compared with placebo (109700).
• Cachexia. Oral melatonin does not seem to improve appetite or body composition in patients with cachexia and cancer. Details: Clinical research in cachectic patients with advanced lung or gastrointestinal cancers shows that taking melatonin 20 mg each evening for 28 days does not improve appetite, body weight, or body composition when compared with placebo (88287).
• Cancer-related fatigue. Oral melatonin does not seem to improve fatigue in patients with cancer. Details: A meta-analysis of five clinical trials shows that taking melatonin does not reduce fatigue in patients with cancer (109697). Most studies used melatonin 20 mg daily, with a duration of 7 days to one year (99344,109697). Although most studies included in the analysis were small, one contained over 700 patients and lasted one year. However, some research disagrees. Preliminary clinical research in adults with breast cancer shows that taking melatonin 18 mg orally daily for 2 years moderately improves fatigue scores when compared with placebo (112054).
• Cancer-related pain. Oral melatonin does not seem to improve pain in patients with cancer. Details: A meta-analysis of five clinical trials shows that taking melatonin does not reduce pain in patients with cancer (109697). Most studies used melatonin 20 mg daily, with a duration of 10 days to one year (109697). Although most studies included in the analysis were small, one contained over 700 patients and lasted one year.
• Critical illness (trauma). Oral melatonin does not seem to be beneficial for reducing hospital stay in critically ill patients. Details: A meta-analysis of clinical research in critically ill patients shows that taking melatonin does not reduce the length of stay in the ICU or the hospital, or affect mortality or sleep quality, when compared with placebo (109696). One additional small clinical study shows that receiving melatonin 3 mg through a nasogastric tube once at 9 pm, followed by a 0.5 mg hourly maintenance dose for 6 hours during the overnight period, does not improve sleep when compared with placebo in patients in the ICU that are being weaned off sedatives and mechanical ventilation (104997).
• Dementia. Oral melatonin does not seem to improve behavior or cognition in patients with dementia. However, it might reduce evening confusion (sundowning). Details: Most clinical research shows that taking melatonin does not improve cognition or behavioral or affective symptoms in patients with probable Alzheimer disease or other forms of dementia (62421,62530,96319). However, some research shows that taking melatonin 2.5-3 mg before bedtime for up to 10 weeks reduces sundowning, which is the confusion and restlessness experienced by some dementia patients in the evening (62788).
• Infertility. Oral melatonin does not seem to increase fertility in females undergoing in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI). Details: Some clinical research shows that taking melatonin does not improve fertility rate or clinical pregnancy rate in adults undergoing IVF, although oocyte and embryo quality might be improved (62775,62818,62819,88297,89512). Also, results from meta-analyses of clinical research show that melatonin does not improve clinical pregnancy rate, total number of oocytes retrieved, or the rate of miscarriage, although it seems to increase the number of mature oocytes (89505,106304). Most studies have used single doses of 3 mg daily which may not be adequate (106304). Melatonin has also been evaluated in adults undergoing ICSI. Although one study shows that taking melatonin improves the fertilization rate, the clinical pregnancy rate was not evaluated (88297). Other research in females taking melatonin and undergoing ICSI does not show an increase in clinical pregnancy rate (97445).
• Shift work disorder. Oral melatonin does not seem to improve sleep in individuals doing shift work. Details: Taking melatonin orally doesn't seem to significantly improve the time it takes to fall asleep (sleep latency), sleep efficiency, or adjustment to rotating shift work. However, slight increases in total sleep time during the day or overall sleep quality may occur (1052,1054,1721,14283,62200,62401,62462,62942).

LIKELY INEFFECTIVE

• Benzodiazepine withdrawal. Oral melatonin does not facilitate benzodiazepine discontinuation in patients with insomnia. Details: Although some small studies show benefit (349,1751), results from larger clinical studies and a meta-analysis of clinical research show that taking melatonin 2-5 mg before bedtime for up to 6 weeks does not help facilitate benzodiazepine discontinuation in patients with insomnia (62464,62467,63075,88295,96321,96323).
• Depression. Most research shows that oral melatonin does not reduce symptoms of depression or prevent depression. In some patients, taking melatonin might make symptoms worse. Details: Most research shows that taking melatonin 5-10 mg daily before bedtime for 4-12 weeks, alone or with fluoxetine, does not improve depression symptoms in patients with rapid cycling bipolar disorder (1766) or major depressive disorder (MDD) (1053,62746,96326). However, some research shows that taking slow-release melatonin 3 mg in combination with immediate-release buspirone 15 mg daily for 6 weeks is more effective at improving depression severity and depression symptoms than placebo or buspirone alone in patients with MDD (88289). However, buspirone is not commonly used for the management of depression. Also, there is some concern that oral melatonin may worsen symptoms in some patients with unipolar or bipolar depression (1764). Evidence regarding the effects of melatonin for preventing depression is unclear. One clinical study shows that taking melatonin 6 mg daily for 12 weeks reduces the percentage of breast cancer patients who develop depression following a lumpectomy or mastectomy by about 75% when compared with placebo when an intention to treat analysis is used. However, when only patients who took all of the doses are considered, melatonin does not appear to have an effect (89511). Also, a meta-analysis of clinical research including two studies in patients with irritable bowel syndrome (IBS) who were at risk for depression shows that melatonin does not prevent depression when compared with placebo (96326).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Acute kidney injury (AKI). It is unclear if oral melatonin is beneficial for acute kidney injury. Details: A meta-analysis of randomized clinical trials in adults with drug-induced acute kidney injury shows that taking melatonin 3-30 mg orally daily for up to 6 days modestly improves glomerular filtration rate, but not serum creatinine or incidence of acute kidney injury, when compared with placebo (111463).
• Age-related macular degeneration (AMD). It is unclear if oral melatonin prevents vision loss in patients with AMD. Details: Preliminary clinical research shows that taking melatonin 3 mg daily for 3-6 months may delay the loss of clear vision in individuals with AMD when compared with baseline (62419). The validity of this finding is limited by the lack of a comparator group.
• Atopic dermatitis (eczema). Oral melatonin might improve some symptoms of atopic dermatitis. However, it is unclear if it improves sleep in this population. Details: Preliminary clinical research in children ages 1-18 years with atopic dermatitis and sleep disturbance shows that taking melatonin 3 mg daily for 4 weeks modestly reduces the overall atopic dermatitis symptom score by 19% when compared with placebo (97439). In another clinical study in children with atopic dermatitis, taking melatonin 6 mg daily 1 hour before bedtime for 6 weeks seems to improve disease severity and sleep quality when compared with placebo (99347). It is unclear whether melatonin improves sleep latency in this population, as conflicting results exist (97439,99347).
• Attention deficit-hyperactivity disorder (ADHD). It is unclear if oral melatonin is beneficial for ADHD. Details: Some small clinical studies in children with ADHD who are taking stimulants show that melatonin 3-5 mg daily for up to 3 months might reduce insomnia when compared with placebo (9980,15034). However, improved sleep related to melatonin treatment does not seem to result in fewer symptoms of ADHD (15034).
• Autism spectrum disorder. It is unclear if oral melatonin is beneficial for this condition. Details: One clinical trial in children aged 6-15 years with autism spectrum disorder shows that taking melatonin (Nobelpharma Co., Ltd) 1 mg or 4 mg before bedtime does not affect behavior when compared with placebo. However, this study was designed to evaluate sleep outcomes, not behavior, as a primary endpoint (106293). Also, a secondary analysis of results from a clinical trial in children with autism spectrum disorder shows that taking prolonged-release melatonin mini-tablets (PedPRM) 2-5 mg nightly for 13 weeks improves externalizing behavior in 26% more patients when compared with those taking placebo. There was no difference between groups in behaviors such as hyperactivity, inattention, emotional behavior, and relationships with peers (101256). The validity of these findings is limited by the secondary nature of the analysis, which was not designed to evaluate these outcomes.
• Benign prostatic hyperplasia (BPH). It is unclear if oral melatonin is beneficial for BPH. Details: One very small clinical study shows that taking controlled-release melatonin 2 mg nightly for 4 weeks reduces excessive urination at night in some men with BPH when compared with placebo. However, it is unclear if this improvement is clinically significant (62360).
• Bipolar disorder. It is unclear if oral melatonin is beneficial for this condition. Details: Preliminary clinical research shows that taking melatonin 3 mg at bedtime for 30 days increases sleep duration and reduces mania severity when compared to baseline in patients with bipolar disorder and treatment-resistant insomnia (62140). However, other research shows that melatonin is not beneficial in patients with bipolar disorder when compared with placebo. Taking melatonin 3-10 mg daily before bedtime for 3-12 weeks does not seem to improve mania or other symptoms when compared with placebo (1766,103694). Also, taking a specific brand of slow-release melatonin (Cronocaps, Productos Medix) 5 mg each evening for 8 weeks may attenuate the increase in blood pressure and fat mass that is associated with use of second-generation antipsychotics, but it does not appear to improve mania or depression in patients with bipolar disorder (88300). There is also some concern that oral melatonin may worsen symptoms in some patients with bipolar depression (1764).
• Bronchopulmonary dysplasia. It is unclear if oral melatonin reduces the risk of bronchopulmonary dysplasia (BPD) in premature infants. Details: A small clinical study in premature infants with respiratory distress syndrome who received surfactant shows that giving melatonin 3 mg daily for 7 days reduces the incidence of BPD to 45%, compared with 60% in those not receiving melatonin. Melatonin also reduced the duration of hospital stay, need for mechanical ventilation, and mortality (108948).
• Chronic fatigue syndrome (CFS). It is unclear if oral melatonin is beneficial for patients with CFS. Details: Many patients with CFS have circadian rhythm disturbances. Some very small clinical studies have evaluated the use of melatonin for addressing these disturbances. One study shows that taking melatonin 5 mg in the evening for 12 weeks might improve some measures of fatigue, concentration, motivation, and activity when compared with baseline (14437). However, other preliminary clinical research shows that taking the same dose of melatonin does not improve CFS symptoms when compared with placebo (9705). Melatonin has also been studied in combination with zinc. In patients with CFS, taking melatonin 1 mg plus zinc 10 mg before bedtime for 16 weeks modestly reduces self-reported levels of physical fatigue, but not self-reported cognitive or psychological symptoms, mood, sleep quality, or quality of life (QOL) measures, when compared with placebo. However, some measures of sleep quality and QOL worsened within 4 weeks of melatonin discontinuation, suggesting that there may have been a modest benefit (106241). It is unclear whether any benefit is related to melatonin, zinc, or the combination. Also, all patients in this study were White females, limiting the generalizability of the results.
• Chronic obstructive pulmonary disease (COPD). It is unclear if oral melatonin is beneficial for COPD. Details: Some clinical research shows that taking melatonin 3 mg daily for 3 months improves shortness of breath in patients with COPD when compared with placebo, although melatonin does not seem to improve lung function or exercise capacity (62854).
• Cluster headache. It is unclear if oral melatonin prevents cluster headaches. Details: A very small clinical study in adults with cluster headaches shows that taking melatonin orally 10 mg every evening for 14 days might reduce the frequency of episodic cluster headaches when compared with placebo (1127). However, 2 mg at bedtime does not seem to be effective (9702).
• Cognitive impairment. Oral melatonin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research in adults 70 years and older with mild cognitive impairment shows that taking two capsules containing melatonin 5 mg, docosahexaenoic acid (DHA) 720 mg, eicosapentaenoic acid (EPA) 286 mg, vitamin E 16 mg, soy phospholipids 160 mg, and L-tryptophan 95 mg (IBSA Farmaceutici) before bedtime for 12 weeks modestly improves cognitive function and sensitivity to smells when compared with placebo. The observed improvement on the mini-mental state examination (MMSE) scale falls below the score generally considered to be indicative of true changes in cognitive function, and may not be clinically significant. Also, it is not known if any potential benefit is due to melatonin, other ingredients, or the combination (62847).
• Colorectal cancer. It is unclear if oral melatonin is beneficial for colorectal cancer prevention. Details: Population research suggests that any history of melatonin use is associated with an approximate 20% reduction in the incidence of colorectal cancer, especially rectal cancer, in individuals aged 60 years and older (106291).
• Contraception. Although there has been interest in using oral melatonin for contraception, there is insufficient reliable information about the clinical effects of melatonin for this use.
• Coronary artery bypass graft (CABG) surgery. It is unclear if oral melatonin is beneficial for recovery from CABG surgery. Details: Clinical research shows that taking melatonin perioperatively during CABG surgery reduces the length of stay in the ICU by about 0.5 days and modestly reduces levels of creatine kinase-MB when compared with placebo. However, there was no effect on the length of hospital stay or levels of cardiac troponin-I, C-reactive protein, or erythrocyte sedimentation rate. Oral melatonin 3 mg was provided the night before and morning of surgery, as well as at bedtime for 3 days after surgery (109699).
• Coronavirus disease 2019 (COVID-19). Preliminary clinical studies suggest that oral melatonin may reduce disease severity in patients with COVID-19, although some conflicting findings exist. Details: A meta-analysis of mainly small and preliminary randomized clinical trials in patients with COVID-19 shows that taking melatonin improves clinical outcomes when compared with placebo. However, the clinical outcomes differed between individual trials, and included specific symptoms, hospital discharge, removal from quarantine, and survival. Dosing also varied, with doses of 2-24 mg daily in 1-4 divided doses for 6-14 days. There was no effect of melatonin on C-reactive protein levels or oxygen saturation (109695). Individual clinical trials have been conducted in hospitalized and/or non-hospitalized patients with mild to severe COVID-19. One clinical trial in outpatients with mild to moderate COVID-19 shows that taking melatonin 10 mg daily modestly reduces time to symptom resolution and quality of life improvement when compared with placebo (109462). However, it is unclear if any beneficial effects are clinically meaningful. In patients hospitalized and receiving standard care for mild to moderate COVID-19, a small clinical trial shows that taking melatonin 3 mg three times daily for 14 days reduces the mean time to hospital discharge by approximately 3.5 days when compared with placebo. Also, persistent symptoms of cough, dyspnea, and fatigue after 14 days occurred in only 0% to 8% of patients taking melatonin, compared with 15% to 30% of those taking placebo. However, there was no difference in the number of patients with other symptoms, including fever, myalgia, chill, and headache (106300). The validity of this study is limited by its high attrition rate. Another small clinical trial in patients hospitalized with COVID-19 shows that taking melatonin (Norm Life Vanatonin Melatonin) 3 mg nightly for 7 days does not reduce symptoms or prevent ICU admission or death when compared with standard care alone (106295). The low dose and short duration of use in this study might have played a role in the lack of benefit. Melatonin has also been evaluated in patients hospitalized for severe COVID-19. One large single-center preliminary clinical trial shows that taking melatonin 10 mg daily reduces the incidence of thrombosis at day 17 and the incidence of sepsis at day 11 when compared with standard care alone. Death occurred in approximately 17% of patients taking placebo, compared with 1% of those taking melatonin (106289). Another preliminary clinical trial in patients in the ICU for severe COVID-19 shows that taking melatonin (Danna Pharmaceutical Company, Iran) 5 mg twice daily for 7 days results in mortality and invasive mechanical ventilation rates of 67% and 51.4%, respectively, compared with 94% and 70.9% in patients given standard care only. There were also modest improvements in the time to improvement of clinical status and lengths of stay in the hospital and ICU (110297). The validity of these studies is limited by a lack of blinding.
• Delirium. It is unclear if oral melatonin is beneficial for preventing delirium in hospitalized patients; the available research is conflicting. Details: Research is conflicting on whether melatonin reduces the incidence of delirium. One meta-analysis of 10 clinical trials shows that melatonin reduces the incidence of delirium in critically ill patients in the intensive care unit (ICU) by 21% when compared with a control, usually placebo (109696). However, other meta-analyses of 14 small clinical and observational studies of hospitalized patients show that taking melatonin does not reduce the incidence of delirium when compared with control (105003,112440). Melatonin might be less beneficial in non-acute medical patients when compared with postoperative patients or those in the ICU (105003). There is also a lack of consensus within the available research on whether melatonin reduces the duration of delirium in hospitalized patients. One meta-analysis of 10 clinical trials shows that melatonin does not reduce the duration of delirium (109696). However, a meta-analysis of 2 small, randomized controlled trials shows that taking melatonin 3-5 mg daily for 5 or more days reduces the duration of delirium by approximately 2 days when compared with placebo (112051). This analysis is limited by substantial heterogeneity and a lack of dose-response evaluation. Most studies in these analyses have used doses of 0.5-10 mg daily for up to 14 days, although one study used a very high single dose of 50 mg/kg (105003,105891,107809,108949,109696,112051). Some research suggests that melatonin may be beneficial for patients undergoing cardiac procedures. A subgroup analysis of one meta-analysis including 3 small studies suggests that melatonin reduces the incidence of delirium in patients in cardiovascular care units, but not in the general ICU population (112440). Two large clinical studies in the meta-analysis suggest that, in older patients admitted to the ICU after acute heart failure or percutaneous coronary intervention (PCI), taking melatonin 3 mg once daily for up to 7 days is associated with a 27% incidence of delirium, compared with a 37% to 40% incidence with placebo (107809,108949). Additionally, a small clinical study in patients undergoing coronary artery bypass graft (CABG) surgery suggests that taking prolonged-release melatonin (Webber Naturals) 3 mg twice before surgery and twice after surgery reduces the occurrence of delirium over the next 48 hours when compared with placebo (105891). The validity of this study is limited by a high risk of bias due to insufficient blinding and incomplete outcome data. Additionally, a small clinical study shows that receiving melatonin 3 mg through a nasogastric tube once at 9 pm, followed by a 0.5 mg hourly maintenance dose for 6 hours during the overnight period, does not reduce delirium or improve sleep when compared with placebo in patients in the ICU that are being weaned off sedatives and mechanical ventilation (104997).
• Diabetes. Most research shows that oral melatonin is beneficial for improving glycemic control. However, it is unclear if oral melatonin is beneficial in patients with type 2 diabetes. Details: Most research on the use of melatonin for glycemic control has been conducted in mixed populations, such as those with schizophrenia, metabolic syndrome, nonalcoholic steatohepatitis (NASH), or perimenopause (103490,106294,106298). Two recent meta-analyses of clinical research in these populations show that taking melatonin modestly reduces fasting glucose and insulin, insulin resistance, and glycated hemoglobin (HbA1c), and improves insulin sensitivity (106294,106298). The most common doses of melatonin used were 3 -10 mg for 8-24 weeks; however, 10 mg may be more effective (106294,106298). This contrasts with an earlier meta-analysis showing only modest beneficial effects of melatonin on fasting glucose levels and insulin sensitivity (103490). Research on the use of melatonin in patients with type 2 diabetes is limited. One small clinical trial in patients with type 2 diabetes show that taking melatonin (NatureMade) 6 mg daily for 8 weeks does not improve glycemic control (104368). However, this trial may have been underpowered to detect a difference. Another very small study in adults with type 2 diabetes shows that taking melatonin 3 mg daily before bed for 7 days increases absolute glucose level at breakfast on day 7 and the glycemic difference between post-dinner on day 6 and pre-breakfast on day 7 but does not change most measures of glycemic variability including mean glucose levels, pre-prandial glucose levels, and post-prandial glucose levels compared with placebo (112441).
• Diabetic neuropathy. It is unclear if oral melatonin is beneficial for improving pain in patients with diabetic neuropathy. Details: A clinical study in patients with painful diabetic neuropathy living in Iran shows that taking melatonin 3 mg nightly for 1 week and then 6 mg nightly for 7 weeks, in conjunction with pregabalin 150 mg daily seems to reduce pain and sleep interference to a greater degree than placebo and pregabalin (105895).
• Dry mouth. It is unclear if oral melatonin is beneficial for dry mouth caused by radiation treatment. Details: A small clinical study in patients with head and neck cancer undergoing chemoradiation shows that taking melatonin 20 mg orally at bedtime and using 10 mL of melatonin 0.2% oral gargle 15 minutes before each radiation session does not delay the onset or reduce the incidence of grade 2 dry mouth when compared with placebo. However, the incidence of grade 3 dry mouth is delayed by approximately 16 days (96314).
• Dysmenorrhea. It is unclear if oral melatonin is beneficial for dysmenorrhea. Details: A small clinical trial shows that taking melatonin 10 mg nightly before bed during the week of menstruation has a statistically significant effect on pain severity when compared with placebo. However, the pain reduction was not considered clinically significant (106301).
• Dyspepsia. It is unclear if oral melatonin is beneficial for dyspepsia in adults. Details: Preliminary clinical research shows that taking melatonin 5 mg nightly for 12 weeks improves dyspeptic symptoms in individuals with functional dyspepsia. However, the benefit seems to be decreased in patients with prior Helicobacter pylori infection (62456).
• Endotracheal intubation-associated adverse effects. It is unclear if oral melatonin is beneficial for endotracheal intubation-related hemodynamic effects. Details: Clinical research shows that taking immediate-release melatonin (Healthy Hey Nutrition) 6 mg, 2 hours prior to the induction of anesthesia, is as effective as clonidine 0.2 mg for attenuating the hemodynamic response to laryngoscopy and tracheal intubation (103483). It is not known if melatonin prevents other adverse effects associated with endotracheal intubation.
• Endometriosis. It is unclear if oral melatonin reduces endometriosis-related pain. Details: Preliminary clinical research shows that taking melatonin 10 mg daily for 8 weeks reduces pain by about 39% and analgesic use by about 46%, as well as pain during menstruation, intercourse, and evacuation, when compared with placebo in adults with endometriosis (89503). Other clinical research in adults with endometriosis shows that taking melatonin 20 mg orally daily does not improve pain scores or reduce pain during intercourse, urination, or defecation when compared with placebo (111464). However, the study may have been inadequately powered to detect a difference between groups.
• Epilepsy. It is unclear if oral melatonin is beneficial for epilepsy in children or adults. Details: There is some low-quality evidence that taking melatonin 3 mg at bedtime for 3 months might reduce the frequency and duration of both nocturnal and daytime seizures in children aged 2-15 years with epilepsy (9699,9745,9746,62785). Also, taking melatonin 1.5 mg before bed for 3 months might reduce the seizure severity in children with epilepsy that is not successfully controlled with other treatment (62754). Furthermore, taking fast-release melatonin 10 mg daily for 3 weeks seems to reduce diurnal seizure frequency in both adults and children aged 9 years and up with intractable epilepsy (88291). Limited research has also assessed melatonin as an adjunct therapy in adults with seizure disorders. A small clinical study in adults with epilepsy involving generalized onset motor seizures that recurred within the last three days shows that adding melatonin 3 mg before bed to therapy with valproate 20 mg/kg in two divided doses daily for 8 weeks results in 82% of patients having at least a 50% reduction in seizure frequency, compared with only 53% of patients in the group taking valproate and placebo. Adding melatonin may also improve seizure severity (105006). However, other clinical research in adults under valproic acid treatment for idiopathic generalized tonic-clonic seizures alone shows that taking melatonin 3 mg before bed for 8 weeks modestly reduces seizure severity, but not frequency (110299).
• Fibromyalgia. It is unclear if oral melatonin is beneficial for this condition. Details: Preliminary clinical research shows that taking melatonin 3-5 mg daily for up to 60 days may decrease the severity of pain and stiffness, as well as the number of painful joints, in people with fibromyalgia when compared with placebo (9701,62797).
• Gastroesophageal reflux disease (GERD). It is unclear if oral melatonin is beneficial for GERD. Details: Clinical research shows that taking melatonin 3 mg daily at bedtime for 8 weeks may improve symptoms of GERD, including heartburn and epigastric pain. However, taking omeprazole 20 mg twice daily seems to be more effective (62723).
• Helicobacter pylori. It is unclear if oral melatonin is beneficial for Helicobacter pylori eradication. Details: One very small clinical study shows that taking melatonin 5 mg twice daily in combination with omeprazole 20 mg twice daily for 21 days improves ulcer healing rates when compared with omeprazole alone in individuals with H. pylori-associated gastroduodenal ulcers (62803).
• Heart failure. It is unclear if oral melatonin is beneficial for heart failure. Details: A small clinical study in adults with stable NYHA class II or III heart failure with reduced ejection fraction (HFrEF) and a left ventricular ejection fraction (LVEF) below 40%, shows that taking melatonin 10 mg orally every evening for 24 weeks improves a composite score reflecting all-cause mortality, hospitalization for exacerbation, and quality of life when compared with placebo. Melatonin also attenuates an increase in serum B-type natriuretic peptide levels, but does not affect LVEF or left ventricular end-diastolic or end-systolic diameter (108950).
• Irritable bowel syndrome (IBS). It is unclear if oral melatonin is beneficial for IBS. Details: In patients with IBS who also have poor sleep, taking melatonin 3 mg at bedtime for 2 weeks seems to decrease symptoms of IBS-related abdominal pain and increase the rectal pain threshold when compared with placebo. However, taking melatonin does not seem to influence stool frequency or consistency, bloating, mood, sleep, or overall quality of life (13112). In other small clinical studies, taking melatonin 3 mg at bedtime for 8 weeks decreased severity and frequency of pain, reduced bloating, improved bowel habits, decreased extracolonic symptoms such as headache, heartburn and nausea, and improved overall quality of life when compared with placebo (15216,62410). However, other clinical research shows that melatonin does not significantly affect the amount of time needed for food to travel through the colon in patients with IBS (62500). Also, one small clinical study shows that taking melatonin 3 mg in the morning and 5 mg in the evening for 6 months improves abdominal pain, bloating, and bowel habits in 50% to 70% of postmenopausal patients with constipation-predominant IBS when compared with placebo. However, beneficial effects were reduced in patients with diarrhea-predominant IBS (89510). Other clinical research in patients with IBS shows that taking melatonin 6 mg orally daily for 8 weeks improves IBS symptom severity scores, abdominal pain scores, and bloating scores, when compared with placebo. These results were not different between those with or without sleep disorders at baseline (112055). The large number of endpoints, many with inconsistent results, in these studies makes it difficult to draw conclusions.
• Ischemia-reperfusion injury. It is unclear if intravenous or intracoronary melatonin is beneficial for ischemia-reperfusion injury. Details: A meta-analysis of 9 low-quality clinical trials in patients with myocardial ischemia-reperfusion injury shows that giving melatonin in doses of 2-50 mg by intravenous or intracoronary injection within 2.5-3.5 hours of ischemia onset improves left ventricular ejection fraction and reduces the infarct size, but does not improve left ventricular end-diastolic or end-systolic volumes, when compared with control. Also, giving melatonin orally for up to 12 weeks does not improve cardiac function. The patients in this study experienced injury as a result of an ST-elevation myocardial infarction, ischemic heart disease, acute coronary syndrome, or coronary heart disease (108946).
• Kidney failure. It is unclear if oral melatonin is beneficial for improving mood and quality of life in patients on hemodialysis. Details: A small clinical trial in patients undergoing hemodialysis shows that taking immediate-release melatonin 3 mg (Puritans Pride, USA) for 3 months modestly improves depression, anxiety, and quality of life when compared with placebo. After treatment, 73.1% and 57.7% of those taking placebo had severe depression and anxiety, respectively, when compared with 22.2% and 14.8% of those taking melatonin (110291).
• Kidney transplant. It is unclear if oral melatonin is beneficial for improving post-transplant kidney function. Details: A small clinical study in patients that have received kidney transplants shows that taking melatonin 3 mg daily for an average of 25 days does not affect urine volume or kidney function, as measured by the blood urea nitrogen over creatinine (BUN/Cr) ratio, when compared with placebo (103693).
• Lung cancer. It is unclear if melatonin is beneficial in patients with early stage non-small cell lung cancer (NSCLC). Details: A clinical study in patients who have undergone complete surgical resection of early stage NSCLC shows that taking melatonin 20 mg daily for 1 year does not improve 2-5 year disease-free survival, pain, anxiety, fatigue, or quality of life when compared with placebo (105894). The validity of these findings is limited by a high study withdrawal rate.
• Melasma. Although there has been interest in using oral melatonin for melasma and other causes of hyperpigmentation, there is insufficient reliable information about the clinical effects of melatonin for these conditions.
• Menopausal symptoms. It is unclear if oral melatonin is beneficial for improving symptoms of menopause; evidence is conflicting. Details: A meta-analysis of 3-5 clinical studies in patients with menopausal symptoms shows that taking melatonin does not seem to improve vasomotor or psychological symptoms, but may modestly improve physical symptoms, when compared with placebo (105897). This analysis is limited due to inconsistent evidence and some risk of bias within the included studies. Studies included in the meta-analysis used melatonin 3 mg daily for 3-12 months alone or in combination with soy isoflavones 80 mg or fluoxetine 20 mg (11806,62840,105897). In contrast, a small study in adults with menopausal symptoms shows that taking melatonin 3 mg daily for 12 weeks improves climacteric symptoms, anxiety, depressive symptoms, sleep quality, and menopausal quality of life and decreases luteinizing hormone and follicle stimulating hormone levels but does not change uterine volume, endometrial thickness, or estradiol levels when compared with placebo (112443).
• Metabolic syndrome. It is unclear if oral melatonin is beneficial for this condition. Details: Preliminary clinical research in adults with metabolic syndrome shows that taking melatonin 5 mg nightly for 2 months reduces systolic and diastolic blood pressure, as well as low-density lipoprotein (LDL) cholesterol levels, when compared to baseline (62795). The validity of these findings is limited by the lack of a comparator group.
• Multiple sclerosis (MS). It is unclear if oral melatonin is beneficial for MS. Details: A small clinical study in patients with relapsing-remitting MS (RRMS) receiving interferon-beta once weekly shows that taking melatonin 3 mg daily for 12 months does not affect relapse rate, disability, brain lesions, fatigue, or depression when compared with placebo (99345). This small study may not have been adequately powered to detect a difference between groups.
• Myocardial infarction (MI). The benefits of administering oral or intravenous melatonin immediately after an MI are unclear. Details: A meta-analysis of 5 small clinical studies in patients after MI shows that oral or intravenous melatonin, used in conjunction with medical reperfusion, is associated with modestly lower troponin levels and modestly higher left ventricular ejection fraction when compared with control (105889). One clinical study included in this analysis that evaluated patients with ST-segment elevation myocardial infarction (STEMI) shows that intravenous administration of melatonin 51.7 mcmol over 60 minutes immediately prior to percutaneous coronary intervention, combined with a bolus intracoronary dose of melatonin 8.6 mcmol administered within 60 seconds after restoration of blood flow to the infarcted artery, does not reduce myocardial infarct size when compared with placebo. However, subgroup analyses suggest that the timing of melatonin administration after symptom onset may alter its effects (96324).
• Neonatal encephalopathy. It is unclear if oral or intravenous melatonin is beneficial for neonates with encephalopathy. Details: A meta-analysis of two small clinical studies in term or late preterm infants with neonatal encephalopathy who are receiving therapeutic hypothermia shows that receiving melatonin 5 mg/kg intravenously daily for 3 days, or 10 mg/kg orally daily for 5 days, does not reduce mortality when compared with hypothermia alone, although a nonsignificant trend towards a reduction was noted (104994). One of those small studies in term infants with neonatal encephalopathy also shows that receiving adjunct oral melatonin treatment results in fewer seizures and less white matter abnormalities when compared with hypothermia alone (99333).
• Nocturnal enuresis. It is unclear if oral melatonin is beneficial for reducing nighttime wettings. Details: Preliminary clinical research shows that taking melatonin 5 mg nightly before bedtime for 3 months does not reduce the number of wet beds when compared with placebo in children with nighttime wettings (nocturnal enuresis) (62824).
• Nonalcoholic fatty liver disease (NAFLD). It is unclear if oral melatonin is beneficial for NAFLD. Details: A meta-analysis of clinical research, as well as individual clinical trials, show that taking melatonin 6-18 mg daily for 4-56 weeks improves some liver indices, but not others (62853,88285,103484,103485). Overall, taking melatonin seems to modestly reduce levels of alkaline phosphatase (ALP) and gamma-glutamyltransferase (GGT). However, there is no effect on alanine aminotransferase (ALT) and levels of aspartate aminotransferase (AST) slightly increased (103485). One small clinical study shows that taking melatonin (Nature Made, USA) 6 mg daily for 12 weeks has a small benefit on systolic and diastolic blood pressure, body mass index (BMI), abdominal circumference, and liver enzymes, but not plasma lipid levels, when compared with placebo (103484). Larger studies are needed to determine the effect of melatonin in this population.
• Obesity. It is unclear if melatonin is beneficial for improving weight loss. Details: A meta-analysis of clinical research shows that taking melatonin up to 10 mg daily, usually for 4-24 weeks, modestly reduces body weight when compared with placebo. However, there was no effect on body mass index (BMI) or waist circumference. Also, the studies included in the analysis were not limited to overweight or obese individuals. Populations included those with metabolic syndrome, nonalcoholic steatohepatitis (NASH), schizophrenia, polycystic ovary syndrome (PCOS), and others, as well as postmenopausal adults (106288). A small clinical trial in overweight or obese individuals shows that although taking melatonin 3 mg daily for 12 weeks modestly reduces waist circumference and body fat mass when compared with placebo, there is no effect on body weight or BMI (106290).
• Oral mucositis. Most research shows that melatonin does not prevent or reduce the severity of oral mucositis in patients with head and neck cancer receiving radiation and chemotherapy. It is unclear if oral or topical melatonin is beneficial in patients with other types of cancer. Details: A meta-analysis of seven clinical trials including patients undergoing chemotherapy or radiotherapy shows that melatonin does not reduce the rate of oral mucositis when compared with a control, usually placebo (109697). Although a small clinical study in patients with head and neck cancer undergoing radiation and chemotherapy with cisplatin shows that melatonin delays the onset of severe mucositis by 16 days when compared with placebo (96314), a meta-analysis shows that melatonin does not reduce the rate of oral mucositis in patients with head and neck cancer (109697). A sub-analysis in one meta-analysis suggests that taking melatonin, usually 20 mg daily, reduces the rate of oral mucositis by 53% in patients with cancer types other than head and neck (109697). Most studies investigating the effect of melatonin have used oral melatonin 20 mg at bedtime. However, in one study, 10 mL of melatonin 0.2% oral gargle was also used 15 minutes before radiation (96314). In another, swishing with 10 mL of a melatonin 3% gel mouthwash for 2 minutes and then swallowing, starting 2-3 days before radiotherapy and continuing until 1-4 weeks after the end of radiotherapy, was used (105893). Melatonin has also been investigated for oral mucositis severity. Although some individual research disagrees (96314), a meta-analysis of three clinical trials shows that melatonin does not reduce the severity of oral mucositis when compared with placebo. However, the form of melatonin provided in these studies was heterogeneous, including oral, gargle, and gel formulations (96314,105893,109697).
• Osteopenia. It is unclear if oral melatonin is beneficial for improving bone mineral density. Details: A small clinical study in postmenopausal adults with osteopenia shows that taking melatonin 3 mg nightly for 1 year increases tibia thickness by 2.2% and volumetric bone mineral density (BMD) in the spine by 3.6% when compared with placebo. However, the BMD of other skeletal sites was not impacted. Additionally, a 1 mg melatonin dose was not beneficial (99334).
• Osteoporosis. Although there has been interest in using oral melatonin for osteoporosis, there is insufficient reliable information about the clinical effects of melatonin for this condition.
• Pain (acute). It is unclear if oral melatonin is beneficial for acute pain. Details: Clinical research in patients undergoing laparoscopic cholecystectomy shows that taking melatonin 6 mg two hours before induction with propofol reduces the number of patients requiring intraoperative fentanyl to 10%, compared with 35% of those taking placebo (106299). Also, preliminary clinical research in preterm infants also given standard treatments shows that oral melatonin (Syrup Trunap, Brio Bliss Life Science Pvt. Ltd) 20 minutes prior to retinopathy of prematurity screening, is not inferior to 24% sucrose for reducing pain (110295). However, the effect of sucrose itself is inconclusive and this study is limited by a lack of blinding. Also, it is unclear if melatonin is beneficial for other causes of acute pain.
• Pain (chronic). It is unclear if melatonin is beneficial for most causes of chronic pain. Details: A meta-analysis of 5 clinical studies shows that taking melatonin 3-12 mg daily for up to 12 weeks modestly reduces chronic pain when compared with placebo (103692). However, it is difficult to draw clinical conclusions from this analysis, as it pools the effects observed in various types of chronic pain, including migraine, burning mouth syndrome, endometriosis, and irritable bowel syndrome (IBS).
• Periodontitis. Small clinical studies suggest that oral melatonin may improve some measures of periodontitis severity. Details: A meta-analysis of 7 small clinical trials in patients with periodontitis treated with subgingival instrumentation to remove calculus and bacterial biofilms shows that adding oral melatonin in doses of 3-10 mg daily improves probing depth, clinical attachment loss, and gingival index when compared with instrumentation alone (108953).
• Polycystic ovary syndrome (PCOS). It is unclear if melatonin is beneficial for PCOS. Details: A prospective cohort study in patients with PCOS has found that taking melatonin (Armonia Fast, Nathura) 2 mg before bedtime for 6 months increases follicle-stimulating hormone and the total number of menstrual cycles from approximately 2.5 to 4 when compared to baseline (96313). The validity of this study is limited by its observational nature and the lack of a comparator group. Additionally, a small clinical study in patients with PCOS shows that taking melatonin 6 mg daily for 8 weeks does not affect insulin levels, fasting blood glucose, lipid levels, or weight, but might modestly reduce testosterone levels, when compared with placebo (105887). This study may have not been adequately powered to detect differences between groups.
• Postoperative nausea and vomiting (PONV). It is unclear if melatonin is beneficial for reducing PONV. Details: A small clinical trial shows that taking melatonin (Nature Made, USA) 3 mg, 5 mg, or 10 mg, one hour prior to lumbar discectomy surgery does not reduce postoperative nausea when compared with placebo (110294).
• Postoperative pain. It is unclear if melatonin is beneficial for reducing pain postoperatively. Details: Three meta-analyses, as well as most individual clinical studies, show that taking melatonin in addition to standard therapy modestly alleviates pain and reduces analgesic use after surgery when compared with placebo (62471,62512,62551,62743,88293,88294,103488,103691,103692,105892)(110294,111462). However, any benefit is likely to be small and may not be clinically relevant (103488,109701,111462). Melatonin has been used in doses of 1-10 mg daily for a duration of 1-21 days, usually starting the night before surgery (62471,62512,62743,103488,103691,105892,110294,111462). This research is limited by poor methodology, as well as the heterogeneity of the included studies. The studies evaluated melatonin across a wide variety of surgeries, including abdominal hysterectomy, cataract surgery, cesarean section, prostatectomy, lumbar laminectomy, lumbar discectomy, laparoscopic cholecystectomy, wisdom teeth extraction, and corrective jaw surgery.
• Postoperative recovery. It is unclear if oral melatonin improves the rate of recovery after surgery. Details: In females undergoing total abdominal hysterectomy, taking extended-release melatonin 5 mg, 90 minutes before surgery, shortens hospital stay to a mean of 2.7 days, compared with 3.4 days for placebo (108945).
• Postoperative sleep disturbance. It is unclear if melatonin is beneficial for improving postoperative sleep disturbance. Details: A meta-analysis of randomized trials in adults undergoing anesthesia for surgery shows that taking melatonin 5-12 mg orally or sublingually or ramelteon 8 mg orally daily for 1-6 days does not improve sleep scores or sleep time when compared with placebo or no intervention (112052). In addition, a small clinical trial shows that taking melatonin (Nature Made) 5 mg each night before bed for 4 weeks, starting 2 weeks after surgery for orthopedic trauma, does not reduce postoperative sleep disturbance when compared with placebo. All patients were also given education related to sleep hygiene (110293).
• Postural tachycardia syndrome (POTS). It is unclear if melatonin is beneficial for POTS. Details: Preliminary clinical research in patients with POTS shows that taking a single dose of melatonin 3 mg reduces sitting and standing heart rate, after 2 and 4 hours, when compared with placebo. However, melatonin does not appear to affect blood pressure or orthostatic symptoms (88292). It is unclear if melatonin is beneficial when taken as more than a single dose.
• Pre-eclampsia. It is unclear if oral melatonin reduces the severity of pre-eclampsia. Details: A small clinical trial in patients with pre-eclampsia shows that taking sustained-release melatonin 10 mg with vitamin B6 10 mg three times daily, starting during recruitment and continuing until delivery, attenuates the need to increase the dose of antihypertensive medication on certain days, but does not affect overall pre-eclampsia severity, when compared with control (99341).
• Prostate cancer. Oral melatonin has only been evaluated in combination with medication; its effect when used alone is unclear. Details: One small clinical study in patients with metastatic prostate cancer that is refractory or resistant to treatment with the luteinizing hormone-releasing hormone (LHRH) analogue triptorelin shows that taking melatonin 20 mg daily in combination with intramuscular triptorelin injected every 28 days can decrease levels of prostate-specific antigen (PSA) and growth factors for prostate cancer when compared to baseline (7255). The validity of these findings is limited by the small study size and lack of a comparator group.
• Pruritus. Small clinical trials suggest that oral melatonin might be beneficial for some types of pruritus. Details: One small clinical trial in patients with pruritus due to various types of chronic liver disease shows that taking melatonin 10 mg nightly for 2 weeks modestly reduces the severity, frequency, and extent of pruritus when compared with placebo (106297). Another small clinical study in patients undergoing hemodialysis shows that taking melatonin 10 mg daily for 2 weeks reduces the severity of pruritus and reduces the affected body area when compared with placebo (104996).
• Radiation dermatitis. It is unclear if topical melatonin is beneficial for radiation-related dermatitis. Details: In females with breast cancer, a small clinical study shows that applying a specific melatonin emulsion cream (Praevoskin, PraevoMed GmbH) twice daily during radiation treatment and continuing for another 2 weeks results in fewer cases of grade 1 or 2 acute radiation dermatitis when compared with placebo (99336). In contrast, another clinical trial in patients with breast cancer shows that applying a cream providing melatonin 25 mg and dimethylsulfoxide 150 mg twice daily during and for 3 weeks after radiation treatment does not improve quality of life or breast symptoms at the end of treatment when compared with placebo. However, there was a modest reduction in breast symptoms over time (110298). Other preliminary clinical research in adults receiving radiation for breast cancer shows that applying melatonin cream 25 mg/gram twice daily throughout radiation therapy does not improve radiation dermatitis scores or reduce the need for adjunctive treatment when compared with placebo (112056).
• Rapid eye movement sleep behavior disorder (RBD). It is unclear if oral melatonin is beneficial for RBD. Details: One very small clinical study shows that taking melatonin 3 mg before bed for 4 weeks increases the likelihood of muscle atonia during rapid eye movement (REM) sleep in patients with RBD when compared with placebo (62762). The validity of this finding is limited by the small study size.
• Restless legs syndrome (RLS). It is unclear if oral melatonin is beneficial for RLS. Details: One very small clinical study shows that taking melatonin 3 mg before bedtime does not improve symptoms of RLS and may actually worsen motor symptoms in individuals with RLS when compared with baseline (62753). The validity of this finding is limited by the small study size and lack of a comparator group.
• Rheumatoid arthritis (RA). It is unclear if oral melatonin is beneficial for RA. Details: A small clinical study in patients with RA shows that taking melatonin 6 mg daily for 12 weeks does not affect disease activity or erythrocyte sedimentation rate (ESR) when compared with placebo (105890).
• Sarcoidosis. It is unclear if oral melatonin is beneficial for this condition. Details: One very small clinical study shows that taking melatonin 20 mg daily for one year, followed by 10 mg daily for another year, improves lung function and skin lesions in patients with chronic sarcoidosis when compared with baseline (62435). The validity of this finding is limited by the small study size and lack of a comparator group.
• Schizophrenia. It is unclear if oral melatonin is beneficial for schizophrenia or for attenuating the adverse effects associated with antipsychotic medications. Details: Some clinical research shows that taking melatonin orally 3 mg each evening for 8 weeks reduces the weight gain and increased waist circumference associated with olanzapine when compared with placebo. It also seems to improve some symptoms of schizophrenia (88296). Other clinical research shows that taking a specific brand of slow-release melatonin (Cronocaps, Productos Medix) 5 mg each evening for 8 weeks reduces adverse effects from second generation antipsychotics, such as increased diastolic blood pressure and waist circumference, when compared with placebo. However, it does not seem to improve symptoms of schizophrenia (88300).
• Seasonal affective disorder (SAD). It is unclear if oral melatonin is beneficial for SAD. Details: Some preliminary clinical research shows that oral melatonin, 0.25-2 mg taken daily for 3 weeks, may decrease winter depression symptoms in patients with SAD (10670,62308). However, sublingual melatonin 0.5 mg daily for 6 days does not appear to improve this condition (62388). Reasons for these discrepancies may include the duration of treatment, route of administration, or the severity of SAD at baseline.
• Smoking cessation. It is unclear if oral melatonin is beneficial in patients trying to quit smoking. Details: One very small clinical study shows that taking melatonin 0.35 mg as a single oral dose 3.5 hours after initiation of nicotine withdrawal in smokers seems to reduce subjective symptoms of anxiety, restlessness, irritability, depression, and cigarette craving over the next 10 hours when compared with baseline (2424). The validity of these findings is limited by the small study size and lack of a comparator group.
• Sepsis. It is unclear if oral melatonin is beneficial for sepsis in neonates or adults. Details: There is conflicting research about the effect of melatonin on neonatal sepsis. While some preliminary research in Egypt shows that giving a single dose of melatonin 20 mg in addition to antibiotics reduces sepsis severity, another more recent study did not find a difference in outcomes between groups receiving antibiotics only or antibiotics with melatonin (99339,99340). In adults with early septic shock given standard care, a small clinical trial shows that taking melatonin 50 mg daily for 5 days increases the number of ventilator-free days by 6.9 and the number of vasopressor-free days by 2.6. ICU and hospital lengths of stay were reduced by 5.25 and 6.9 days, respectively. However, after 28 days there was no significant difference in the mortality rate, the number of patients requiring ventilation or renal replacement therapy, or the number of patients recovered from organ dysfunction (106296). Intravenous melatonin has also been investigated. A small clinical trial in patients with severe sepsis shows that a continuous infusion of melatonin, 60 mg over 24 hours, for 5 days following post-surgical sepsis diagnosis modestly reduces sepsis severity when compared with placebo. Hospital stay was reduced by approximately 5.2 days in patients given melatonin; however, it is unclear if this difference is statistically significant (110300).
• Stabbing headache. Although there has been interest in using oral melatonin for stabbing headaches, there is insufficient reliable information about the clinical effects of melatonin for this condition.
• Stress. It is unclear if oral melatonin is beneficial for stress reduction. Details: Preliminary clinical research shows that taking melatonin 3 mg one hour prior to stress modestly improves memory accuracy during a laboratory-induced stressful situation when compared with placebo (62509).
• Tardive dyskinesia. It is unclear if oral melatonin is beneficial for this condition. Details: One small clinical study shows that taking melatonin orally 10 mg daily for 6 weeks decreases symptoms by 24% to 30% in patients with tardive dyskinesia when compared with placebo (7082). However, other small clinical studies show that taking melatonin 2-20 mg daily for 4-12 weeks does not reduce abnormal, involuntary movement in patients with tardive dyskinesia when compared with placebo (62146,62825).
• Tension headache. It is unclear if oral melatonin is beneficial for reducing the frequency of tension headaches. Details: A small clinical study in patients with chronic tension headache shows that taking a specific melatonin supplement (Melaxen) 3 mg nightly for 30 days seems to reduce headache severity and reduce the median number of days with a headache by 6 when compared with baseline (104998). The validity of this finding is limited by the lack of a control group.
• Tinnitus. It is unclear if oral melatonin is beneficial for improving tinnitus intensity or severity. Details: Some clinical research shows that taking melatonin 3 mg nightly for one month reduces tinnitus intensity and improves the quality of sleep in individuals with chronic tinnitus when compared with placebo. The effect seems to be greatest in men, those who have not received prior treatment for tinnitus, and those with a history of noise exposure (62820). Other clinical research shows that taking melatonin 3 mg daily for 3 months is more effective for reducing tinnitus severity than sertraline 50 mg daily (97447). However, other clinical research shows that taking melatonin 3 mg nightly for 30-40 days does not significantly reduce tinnitus intensity when compared with placebo, although the effects might be significant when melatonin is combined with sulpiride or sulodexide (62469,62614).
• Traumatic brain injury (TBI). It is unclear if oral melatonin is beneficial for children who have experienced a concussion. Details: A small clinical study in children ages 8-18 years who have experienced a concussion shows that taking melatonin 3 mg or 10 mg one hour before bedtime for 28 days does not improve persistent post-concussive symptoms when compared with placebo (103690). One small observational study in children in the same age group who have experienced a concussion within 14 days has found that receiving a prescription for melatonin is not associated with improved symptoms and recovery at 15-35 days after concussion (105001). The validity of these findings is limited by small study size and short duration of follow-up.
• Ulcerative colitis. Oral melatonin may be modestly beneficial for reducing symptoms or sustaining remission in patients using the medication mesalazine. Details: A small clinical study shows that taking melatonin 5 mg daily in combination with mesalazine 1 gram twice daily for 12 months may help to sustain remission in patients with ulcerative colitis when compared with mesalazine alone (62821). Another small clinical trial in patients with mild to moderate ulcerative colitis shows that taking melatonin 3 mg daily for 3 months modestly improves overall symptoms, some measures of quality of life, and levels of fecal calprotectin when compared with placebo. However, there was no effect on other markers of inflammation, such as C-reactive protein and erythrocyte sedimentation rate (106303). More evidence is needed to rate melatonin for these uses.

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LIKELY SAFE ...when used orally or intravenously and appropriately. Calcium is safe when used in appropriate doses (7555,12928,12946,95817). However, excessive doses should be avoided. The Institute of Medicine sets the daily tolerable upper intake level (UL) for calcium according to age as follows: Age 0-6 months, 1000 mg; 6-12 months, 1500 mg; 1-8 years, 2500 mg; 9-18 years, 3000 mg; 19-50 years, 2500 mg; 51+ years, 2000 mg (17506). Doses over these levels can increase the risk of side effects such as kidney stone, hypercalciuria, hypercalcemia, and milk-alkali syndrome. There has also been concern that calcium intake may be associated with an increased risk of cardiovascular disease (CVD) and coronary heart disease (CHD), including myocardial infarction (MI). Some clinical research suggests that calcium intake, often in amounts over the recommended daily intake level of 1000-1300 mg daily for adults, is associated with an increased risk of CVD, CHD, and MI (16118,17482,91350,107233). However, these studies, particularly meta-analyses, have been criticized for excluding trials in which calcium was administered with vitamin D (94137). Many of these trials also only included postmenopausal females. Other analyses report conflicting results, and have not shown that calcium intake affects the risk of CVD, CHD, or MI (92994,93533,97308,107231). Advise patients not to consume more than the recommended daily intake of 1000-1200 mg per day and to consider total calcium intake from both dietary and supplemental sources (17484). Also, advise patients taking calcium supplements to take calcium along with vitamin D (93533).

POSSIBLY UNSAFE ...when used orally in excessive doses. The National Academy of Medicine sets the daily tolerable upper intake level (UL) for calcium according to age as follows: 19-50 years, 2500 mg; 51 years and older, 2000 mg (17506). Doses over these levels can increase the risk of side effects such as kidney stones, hypercalciuria, hypercalcemia, and milk-alkali syndrome. There has also been concern that calcium intake may be associated with an increased risk of cardiovascular disease (CVD) and coronary heart disease (CHD), including myocardial infarction (MI). Some clinical research suggests that calcium intake, often in amounts over the recommended daily intake level of 1000-1300 mg daily for adults, is associated with an increased risk of CVD, CHD, and MI (16118,17482,91350,107233). However, these studies, particularly meta-analyses, have been criticized for excluding trials in which calcium was administered with vitamin D (94137). Many of these trials also only included postmenopausal females. Other analyses report conflicting results, and have not shown that calcium intake affects the risk of CVD, CHD, or MI (92994,93533,97308,107231). Advise patients to not consume more than the recommended daily intake of 1000-1200 mg per day and to consider total calcium intake from both dietary and supplemental sources (17484). Also, advise patients taking calcium supplements to take calcium along with vitamin D (93533).

CHILDREN: LIKELY SAFE
when used orally and appropriately. Calcium is safe when used in appropriate doses (17506).

CHILDREN: POSSIBLY UNSAFE
when used orally in excessive doses. The Institute of Medicine sets the daily tolerable upper intake level (UL) for calcium according to age as follows: 0-6 months, 1000 mg; 6-12 months, 1500 mg; 1-8 years, 2500 mg; 9-18 years, 3000 mg (17506). Doses over these levels can increase the risk of side effects such as kidney stones, hypercalciuria, hypercalcemia, and milk-alkali syndrome.

PREGNANCY AND LACTATION: LIKELY SAFE
when used orally and appropriately (945,1586,3263,3264,17506). The World Health Organization (WHO) recommends prescribing oral calcium supplementation 1.5-2 grams daily during pregnancy to those with low dietary calcium intake to prevent pre-eclampsia (97347).

PREGNANCY AND LACTATION: POSSIBLY UNSAFE
when used orally in excessive doses. The Institute of Medicine sets the same daily tolerable upper intake level (UL) for calcium according to age independent of pregnancy status: 9-18 years, 3000 mg; 19-50 years, 2500 mg (17506). Doses over these amounts might increase the risk of neonatal hypocalcemia-induced seizures possibly caused by transient neonatal hypoparathyroidism in the setting of excessive calcium supplementation during pregnancy, especially during the third trimester. Neonatal hypocalcemia is a risk factor for neonatal seizures (97345).

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LIKELY SAFE ...when used orally and appropriately, short-term or as a single dose. Melatonin seems to be safe when used up to 8 mg daily for up to 6 months. Melatonin 10 mg daily has been used safely for up to 2 months (1049,1068,1077,1085,1738,1754,5854,5855,5857,12226), (14283,15005,62850,89502,89503,88285,88289,88293,88294,88295)(88296,88299,89508,89510,89511,96313,96314,96316,96317,96319)(96321,97438,99345,103484,106301,106303,107811,110286,110299). ...when used topically and appropriately (1066,1768,1769,4713,4714,96314).

POSSIBLY SAFE ...when doses of up to 8 mg daily are used orally and appropriately for longer than 6 months, doses of 10 mg daily are used for longer than 2 months, or doses of 50 mg daily are used for up to 5 days (7040,7043,62435,106296,107811). There is some evidence melatonin can be used safely in doses of up to 10 mg daily for up to 2 years in some patients (7040,7043,62435). ...when used intravenously under the supervision of a healthcare professional. A one-time dose of intravenous melatonin combined with a single bolus of intracoronary melatonin has been used with apparent safety in one clinical trial (96324).

CHILDREN: POSSIBLY SAFE
when used orally in low doses, short-term (9980,15034,62792,88282,88283,88286,88288,95748,96318,97434)(97439,97446,106293,110292). Although melatonin has been safely used in clinical research in doses up to 12 mg daily (88283), it is often advised that daily doses of melatonin be limited to 3 mg daily for children and infants 6 months or older and 5 mg daily for adolescents (95746). There is some concern that taking melatonin might adversely affect gonadal development in children (1739,1740,1742,1743). While some evidence suggests that long-term use of melatonin in children may delay puberty, the available research includes only three small, observational studies with incomplete follow-up and poor measures of pubertal timing (95747). Although rare, pediatric overdose with melatonin has resulted in hospitalization, mechanical ventilation, and death (108145). Due to potential risks, melatonin should be used only in children with a medical reason for use; it should not be used to promote sleep in otherwise healthy children. There is insufficient reliable information available about the safety of melatonin when used long-term.

PREGNANCY: POSSIBLY UNSAFE
when used orally or parenterally in high doses or with frequent use. High doses of melatonin 75-300 mg daily seem to inhibit ovulation, causing a contraceptive effect (769,1740,6002,8271,95728). Advise pregnant patients and patients wishing to become pregnant to avoid using melatonin frequently or in high doses. There is insufficient reliable information available about the safety of melatonin in lower doses during pregnancy. Some research shows that taking melatonin 2 mg daily does not affect anterior pituitary hormone levels in females who are not pregnant; this suggests that low doses may not have a contraceptive effect (62898). Other research shows that taking melatonin 3 mg daily during the follicle stimulating stage of in vitro fertilization does not negatively impact pregnancy rates (62818,62819,88297,89512,88297). However, it is not known if melatonin is safe for use throughout pregnancy (95729). Until more is known about the safety of melatonin, avoid using during pregnancy.

LACTATION:
Insufficient reliable information available; avoid using.

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ALUMINUM Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Calcium citrate might increase aluminum absorption and toxicity. Other types of calcium do not increase aluminum absorption.  Details Calcium citrate can increase the absorption of aluminum when taken with aluminum hydroxide. The increase in aluminum levels may become toxic, particularly in individuals with kidney disease (21631). However, the effect of calcium citrate on aluminum absorption is due to the citrate anion rather than calcium cation. Calcium acetate does not appear to increase aluminum absorption (93006).

BISPHOSPHONATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = C Calcium reduces the absorption of bisphosphonates.  Details Advise patients to take bisphosphonates at least 30 minutes before calcium, but preferably at a different time of day. Calcium supplements decrease absorption of bisphosphonates (12937).

CALCIPOTRIENE (Dovonex) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Taking calcipotriene with calcium might increase the risk for hypercalcemia.  Details Calcipotriene is a vitamin D analog used topically for psoriasis. It can be absorbed in sufficient amounts to cause systemic effects, including hypercalcemia (12938). Theoretically, combining calcipotriene with calcium supplements might increase the risk of hypercalcemia.

CALCIUM CHANNEL BLOCKERS Interaction Rating = Minor Be watchful with this combination. Severity = Moderate •  Occurrence = Unlikely •  Level of Evidence = D Intravenous calcium may decrease the effects of calcium channel blockers; oral calcium is unlikely to have this effect.  Details Intravenous calcium is used to decrease the effects of calcium channel blockers in the management of overdose. Intravenous calcium gluconate has been used before intravenous verapamil (Isoptin) to prevent or reduce the hypotensive effects without affecting the antiarrhythmic effects (6124). But there is no evidence that dietary or supplemental calcium when taken orally interacts with calcium channel blockers (12939,12947).

CEFTRIAXONE (Rocephin) Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = D Co-administration of intravenous calcium and ceftriaxone can result in precipitation of a ceftriaxone-calcium salt in the lungs and kidneys.  Details Avoid administering intravenous calcium in any form, such as parenteral nutrition or Lactated Ringers, within 48 hours of intravenous ceftriaxone. Case reports in neonates show that administering intravenous ceftriaxone and calcium can result in precipitation of a ceftriaxone-calcium salt in the lungs and kidneys. In several cases, neonates have died as a result of this interaction (15794,21632). So far there are no reports in adults; however, there is still concern that this interaction might occur in adults.

DIGOXIN (Lanoxin) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = B Using intravenous calcium with digoxin might increase the risk of fatal cardiac arrhythmias.  Details Hypercalcemia increases the risk of fatal cardiac arrhythmias with digoxin (12940). However, one retrospective analysis of clinical data suggests that intravenous calcium does not increase the risk of dysrhythmias or mortality in patients receiving digoxin (38960).

DILTIAZEM (Cardizem, others) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = D Theoretically, calcium may reduce the therapeutic effects of diltiazem.  Details Hypercalcemia can reduce the effectiveness of verapamil in atrial fibrillation (10574). Theoretically, calcium might increase this risk of hypercalcemia and reduce the effectiveness of diltiazem.

DOLUTEGRAVIR (Tivicay) Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = B Calcium seems to reduce levels of dolutegravir.  Details Advise patients to take dolutegravir either 2 hours before or 6 hours after taking calcium supplements. Pharmacokinetic research suggests that taking calcium carbonate 1200 mg concomitantly with dolutegravir 50 mg reduces plasma levels of dolutegravir by almost 40%. Calcium appears to decrease levels of dolutegravir through chelation (93578).

ELVITEGRAVIR (Vitekta) Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = B Calcium seems to reduce levels of elvitegravir.  Details Advise patients to take elvitegravir either 2 hours before or 2 hours after taking calcium supplements. Pharmacokinetic research suggests that taking calcium along with elvitegravir can reduce blood levels of elvitegravir through chelation (94166).

LEVOTHYROXINE (Synthroid, others) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Calcium seems to reduce the absorption and effectiveness of levothyroxine.  Details Advise patients to take levothyroxine and calcium supplements at least 4 hours apart. Calcium reduces levothyroxine absorption, probably by forming insoluble complexes (5082). Calcium carbonate supplements reduce effectiveness of levothyroxine in patients with hypothyroidism (5081,5082,6137).

LITHIUM Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, concomitant use of calcium and lithium may increase this risk of hypercalcemia.  Details Clinical research suggests that long-term use of lithium may cause hypercalcemia in 10% to 60% of patients (38953). Theoretically, concomitant use of lithium and calcium supplements may further increase this risk.

QUINOLONE ANTIBIOTICS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Calcium seems to reduce the absorption of quinolone antibiotics.  Details Advise patients to take oral quinolones at least 2 hours before or 4-6 hours after calcium supplements or calcium-fortified foods. Taking calcium at the same time as oral quinolones can reduce quinolone absorption. Calcium binds to quinolones in the gut (4412,10339,21638,38570).

RALTEGRAVIR (Isentress) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = B Calcium may reduce levels of raltegravir.  Details Pharmacokinetic research shows that taking a single dose of calcium carbonate 3000 mg along with raltegravir 400 mg twice daily modestly decreases the mean area under the curve of raltegravir, but the decrease does not necessitate a dose adjustment of raltegravir (94164). However, a case of elevated HIV-1 RNA levels and documented resistance to raltegravir has been reported for a patient taking calcium carbonate 1 gram three times daily plus vitamin D3 (cholecalciferol) 400 IU three times daily in combination with raltegravir 400 mg twice daily for 11 months. It is thought that calcium reduced raltegravir levels by chelation, leading to treatment failure (94165).

SOTALOL (Betapace) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Calcium seems to reduce the absorption of sotalol.  Details Advise patients to separate doses by at least 2 hours before or 4-6 hours after calcium. Calcium appears to reduce the absorption of sotalol, probably by forming insoluble complexes (10018).

TETRACYCLINE ANTIBIOTICS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = C Calcium seems to reduce the absorption of tetracycline antibiotics.  Details Advise patients to take oral tetracyclines at least 2 hours before, or 4-6 hours after calcium supplements. Taking calcium at the same time as oral tetracyclines can reduce tetracycline absorption. Calcium binds to tetracyclines in the gut (1843).

THIAZIDE DIURETICS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = C Taking calcium along with thiazides might increase the risk of hypercalcemia and renal failure.  Details Thiazides reduce calcium excretion by the kidneys (1902). Using thiazides along with moderately large amounts of calcium carbonate increases the risk of milk-alkali syndrome (hypercalcemia, metabolic alkalosis, renal failure). Patients may need to have their serum calcium levels and/or parathyroid function monitored regularly.

VERAPAMIL (Calan, others) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = D Theoretically, calcium may reduce the therapeutic effects of verapamil.  Details Hypercalcemia can reduce the effectiveness of verapamil in atrial fibrillation (10574). Theoretically, use of calcium supplements may increase this risk of hypercalcemia and reduce the effectiveness of verapamil.

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ANTICOAGULANT/ANTIPLATELET DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = B Theoretically, melatonin may have anticoagulant effects and may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.  Details There are isolated case reports of minor bleeding and decreased prothrombin activity in people taking melatonin with warfarin (Coumadin) (63067). The mechanism, if any, of this interaction is unknown (9181). Taking melatonin orally seems to decrease coagulation activity within one hour of dosing in healthy men (62481).

ANTIDIABETES DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, taking melatonin with antidiabetes drugs might increase the risk of hypoglycemia.  Details Some clinical research shows that melatonin reduces levels of fasting blood glucose and improves glycemic control (19034,19035,103490). However, other research suggests that melatonin might impair glucose utilization and increase insulin resistance (9713), while other research has found no effect on glucose levels (19036,104368). Until more is known, use melatonin cautiously in combination with antidiabetes drugs.

ANTIHYPERTENSIVE DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = A Theoretically, taking melatonin with antihypertensive drugs might increase the risk of hypotension or hypertension.  Details Some clinical research suggests that taking melatonin decreases blood pressure in healthy adults (1724,62165,62187,63042). Also, melatonin seems to lower systolic and diastolic blood pressure in individuals with high blood pressure at nighttime or untreated essential hypertension (62359,62416,62441,62826). However, melatonin seems to worsen blood pressure in patients who are taking antihypertensive medications. Immediate-release melatonin 5 mg at night in combination with nifedipine GITS (Procardia XL) increases systolic blood pressure an average of 6.5 mmHg, diastolic blood pressure by an average of 4.9 mmHg, and heart rate by 3.9 bpm (6436). Also, results from animal research suggest that melatonin reduces the effectiveness of certain antihypertensive drugs, including methoxamine and clonidine (62432).

CAFFEINE Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = B Theoretically, taking caffeine with melatonin might increase levels of melatonin.  Details Some evidence suggests that caffeine consumption can decrease endogenous melatonin levels (8265,22303,37585), while other evidence suggests that caffeine increases endogenous melatonin levels (62328). When administered in combination with melatonin supplements, caffeine seems to increase melatonin effects and levels (62352,96315). The reason for this discrepancy is not completely clear. Part of the discrepancy may result from the fact that caffeine can inhibit melatonin synthesis as well as inhibit melatonin metabolism. By functioning as an adenosine receptor antagonist, caffeine may indirectly inhibit the synthesis of melatonin. Conversely, because melatonin and caffeine are both metabolized by cytochrome P450 1A2 (CYP1A2) enzyme, concomitant use of melatonin and caffeine may reduce the metabolism of melatonin, resulting in higher serum levels (22306,96315).

CNS DEPRESSANTS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, taking melatonin might increase the sedative effects of CNS depressants.  Details Melatonin has sedative effects. Theoretically, concomitant use of melatonin with alcohol, benzodiazepines, or other sedative drugs might cause additive sedation (96315).

CONTRACEPTIVE DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Theoretically, taking contraceptive drugs with melatonin might increase the effects and adverse effects of melatonin.  Details Contraceptive drugs can increase the levels of endogenous melatonin (8265). Theoretically, these drugs may increase the effects and adverse effects of oral melatonin.

CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = D Theoretically, melatonin might increase levels of drugs metabolized by CYP1A2. Also, other CYP1A2 substrates might decrease the metabolism of melatonin, increasing melatonin levels.  Details Melatonin is metabolized in the liver primarily by the CYP2C19 and CYP1A2 enzymes (62118,62405,96315). Theoretically, combined administration of melatonin with drugs metabolized by the CYP1A2 enzyme might reduce the metabolism of these drugs, resulting in increased serum levels. Conversely, some drugs metabolized by CYP1A2 may inhibit the metabolism of melatonin, resulting in increased serum levels of melatonin. Until more is known, use melatonin cautiously in patients taking drugs metabolized by these enzymes.

CYTOCHROME P450 2C19 (CYP2C19) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = D Theoretically, melatonin might increase levels of drugs metabolized by CYP2C19. Also, other CYP2C19 substrates might decrease the metabolism of melatonin, increasing melatonin levels.  Details Melatonin is metabolized in the liver primarily by the CYP2C19 and CYP1A2 enzymes (62118,62405). Theoretically, combined administration of melatonin with certain drugs metabolized by the CYP2C19 enzyme may reduce the metabolism of these drugs, resulting in increased serum levels. Conversely, some drugs metabolized by CYP2C19 may inhibit the metabolism of melatonin, resulting in increased serum levels of melatonin. Until more is known, use melatonin cautiously in patients taking drugs metabolized by these enzymes.

CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, melatonin might increase levels of drugs metabolized by CYP2D6.  Details Laboratory research suggests that certain lots of melatonin inhibit CYP2D6 (96315). Theoretically, combined administration of melatonin with certain drugs metabolized by the CYP2D6 enzyme may reduce the metabolism of these drugs, resulting in increased serum levels. Until more is known, use melatonin cautiously in patients taking drugs metabolized by these enzymes.

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, melatonin might increase levels of drugs metabolized by CYP3A4.  Details Laboratory research shows that certain lots of melatonin inhibit CYP3A4 (96315). Theoretically, combined administration of melatonin with certain drugs metabolized by CYP3A4 may reduce the metabolism of these drugs, resulting in increased serum levels. Until more is known, use melatonin cautiously in patients taking drugs metabolized by these enzymes.

FLUMAZENIL (Romazicon) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, taking flumazenil with melatonin might reduce the effects of melatonin.  Details Animal research shows that flumazenil may inhibit the effect of melatonin (9703).

FLUVOXAMINE (Luvox) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Theoretically, taking fluvoxamine with melatonin might increase levels of melatonin.  Details Fluvoxamine can significantly increase melatonin levels. In some cases, fluvoxamine might increase bioavailability of exogenously administered melatonin by up to 20 times (5038,6499,8251). Some researchers think this might be a beneficial interaction and be potentially useful for cases of refractory insomnia (6499). However, this interaction might also cause unwanted excessive drowsiness and possibly other adverse effects. Fluvoxamine is known to increase endogenous melatonin secretion (6498,22313). It seems to increase serum levels of exogenously administered melatonin possibly by decreasing melatonin metabolism by inhibiting cytochrome P450 (CYP450) 1A2 and 2C19 or by inhibiting melatonin elimination. This effect has been found in healthy people taking fluvoxamine 50-75 mg and melatonin 5 mg (5038,6498,6499,8251).

IMMUNOSUPPRESSANTS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = B Theoretically, melatonin might interfere with immunosuppressive therapy.  Details Melatonin can stimulate immune function. Theoretically, melatonin might interfere with immunosuppressive therapy (7040).

METHAMPHETAMINE (Desoxyn) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, taking melatonin with methamphetamine may increase the adverse effects of methamphetamine.  Details Animal research suggests that melatonin exacerbates the adverse effects of methamphetamine, resulting in greater depression of tryptophan hydroxylase (TPH) and tyrosine hydroxylase (TH) activity, as well as a significant reduction in dopamine levels (22307). This has not been shown in humans.

NIFEDIPINE GITS (Procardia XL) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Theoretically, taking melatonin with extended release nifedipine reduces the effects of nifedipine.  Details Melatonin can decrease the effectiveness of extended release nifedipine (GITS). Immediate-release melatonin 5 mg at night in combination with nifedipine GITS 30-60 mg daily increases systolic and blood pressure by an average of 6.5 mmHg and 4.9 mmHg, respectively. Concomitant use with melatonin also increases heart rate by 3.9 bpm (6436). The mechanism of this interaction is not known.

SEIZURE THRESHOLD LOWERING DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, taking melatonin with drugs that lower the seizure threshold might increase the risk of seizure activity.  Details Some clinical evidence suggests that melatonin may increase the frequency of seizures in certain patients, particularly children with neurological disabilities (8248,9744).

WARFARIN (Coumadin) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, melatonin may have antiplatelet effects and may increase the risk of bleeding with warfarin.  Details Three cases of increased prothrombin time have been reported for patients aged 48-72 years who took melatonin orally in combination with warfarin (9181). However, three cases of decreased prothrombin time have also been reported for patients aged 51-84 years who took melatonin orally in combination with warfarin (9181). Until more is known, use melatonin cautiously in patients taking warfarin.

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General ...Orally and intravenously, calcium is well-tolerated when used appropriately.
Most Common Adverse Effects:
Orally: Belching, constipation, diarrhea, flatulence, and stomach upset.
Serious Adverse Effects (Rare):
Orally: Case reports have raised concerns about calciphylaxis and kidney stones.

Cardiovascular ...There has been concern that calcium intake may be associated with an increased risk of cardiovascular disease (CVD) and coronary heart disease (CHD), including myocardial infarction (MI). Some clinical research suggests that calcium intake, often in amounts over the recommended daily intake level of 1000-1300 mg daily for adults, is associated with an increased risk of CVD, CHD, and MI (16118,17482,91350,107233). However, these results, particularly meta-analyses, have been criticized for excluding trials in which calcium was administered with vitamin D (94137). Many of these trials also only included postmenopausal females. Other analyses report conflicting results, and have not shown that calcium intake affects the risk of CVD, CHD, or MI (92994,93533,97308,107231). Reasons for these discrepancies are not entirely clear. It may relate to whether calcium is taken as monotherapy or in combination with vitamin D. When taken with vitamin D, which is commonly recommended, calcium supplementation does not appear to be associated with an increased risk of CVD, CHD, or MI (93533,107231). Also, the association between calcium supplementation and CVD, CHD, or MI risk may be influenced by the amount of calcium consumed as part of the diet. Supplementation with calcium may be associated with an increased risk of MI in people with dietary calcium intake above 805 mg daily, but not in those with dietary calcium intake below 805 mg daily (17482). To minimize the possible risk of CVD, CHD, or MI, advise patients not to consume more than the recommended daily intake of 1000-1200 mg and to consider total calcium intake from both dietary and supplemental sources (17484). While dietary intake of calcium is preferred over supplemental intake, advise patients who require calcium supplements to take calcium along with vitamin D, as this combination does not appear to be associated with an increased risk of MI (93533).
Rarely, calcium intake can increase the risk of calciphylaxis, which usually occurs in patients with kidney failure. Calciphylaxis is the deposition of calcium phosphate in arterioles, which causes skin ulcers and skin necrosis. In a case report, a 64-year-old female with a history of neck fracture, sepsis, and ischemic colitis presented with painful leg ulcers due to calciphylaxis. She discontinued calcium and vitamin D supplementation and was treated with sodium thiosulfate and supportive care (95816).

Gastrointestinal ...Orally, calcium can cause belching, flatulence, nausea, gastrointestinal discomfort, and diarrhea (1824,1843,12950,38803). Although constipation is frequently cited as an adverse effect of calcium, there is no scientific substantiation of this side effect (1824,1843,1844,1845,12950,38978). Calcium carbonate has been reported to cause acid rebound, but this is controversial (12935,12936).

Oncologic ...There is some concern that very high doses of calcium might increase the risk of prostate cancer. Some epidemiological evidence suggests that consuming over 2000 mg/day of dietary calcium might increase the risk for prostate cancer (4825,12949). Additional research suggests that calcium intake over 1500 mg/day might increase the risk of advanced prostate cancer and prostate cancer mortality (14132). Consumption of dairy products has also been weakly linked to a small increase in prostate cancer risk (98894). However, contradictory research suggests no association between dietary intake of calcium and overall prostate cancer risk (14131,14132,104630). More evidence is needed to determine the effect of calcium, if any, on prostate cancer risk.

Renal ...Kidney stones have been reported in individuals taking calcium carbonate 1500 mg daily in combination with vitamin D 2000 IU daily for 4 years (93943).

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General ...Orally, melatonin is generally well tolerated.
Most Common Adverse Effects:
Orally: Dizziness, drowsiness, headache, and nausea.
Serious Adverse Effects (Rare):
Orally: There is concern that melatonin may increase the risk for seizure.

Cardiovascular ...Melatonin might increase levels of very low-density lipoprotein (VLDL) cholesterol and triglycerides (62176). Several rare or poorly described cases of abnormal heart rhythms, palpitations, fast heart rate, or chest pain have been reported. However, in these cases, the patients were taking other drugs that could account for the symptoms, and melatonin was not thought to be the cause (1079,9181,62776,62789,63067).

Dermatologic ...Papular skin rash and pruritus has been reported with melatonin use. However, the effect was generally mild and did not require cessation of melatonin treatment (62450,62754,109696), and had similar rates as placebo (96316). Cutaneous flushing has also been reported (62770,62914). Two cases of fixed drug eruption on the genitalia have been reported for patients who used oral melatonin (Nature's Bounty Natural melatonin) for preventing jet lag (88284).

Endocrine ...A case of gynecomastia (increased breast size) has been reported for a 56 year-old patient with amyotrophic lateral sclerosis (ALS) who used oral melatonin, long-term (89430). Also, reduced sperm concentration and sperm motility has been reported for two men who used oral melatonin 3 mg daily for 6 months. Improvement in sperm quality was observed for only one of the two men following melatonin cessation (62231).

Gastrointestinal ...Orally, melatonin may cause nausea (62384,62770), abdominal cramps, or mild abdominal pain (62450,62754,62914,96316), diarrhea (62804,62811,62914), constipation (96316), or decreased appetite (62345,62792). Often these symptoms occur during the first few days of treatment and subside after a few days (62804). In some cases, rates of symptoms are similar between melatonin and placebo (96316). Less often, melatonin has been reported to cause abnormal feces (62450), odd taste in the mouth (1070), or reflux esophagitis (1745) when used orally. A case of exacerbated symptoms of Crohn disease, including increased diarrhea and abdominal cramps, has been reported for a patient who took oral melatonin 3 mg at bedtime for 4 days. Symptoms resolved within 24 hours of melatonin treatment cessation (62218).

Genitourinary ...Orally, melatonin may increase enuresis in adults and children (58685,62450,62710,62770,62804,62804,62811). In perimenopausal adults, melatonin has caused a resumption of spotting or menstrual flow (11806). Decreased libido has been noted for one patient treated with melatonin 3 mg daily for 8 weeks (15216).

Hematologic ...A case of nose bleed has been reported with oral melatonin (62450). Some melatonin preparations contain contaminants that are associated with eosinophilia-myalgia syndrome (9715,9716).

Hepatic ...A case of autoimmune hepatitis has been reported for a patient who took melatonin orally to treat insomnia (63037).

Musculoskeletal ...Preliminary clinical evidence shows that a single dose of melatonin 3 mg may increase fall risk due to increased postural swaying while standing on one or both feet in healthy adults ages 60-71 years (97442). A single case of ataxia has been reported for an 81-year-old female who used melatonin for 4 days (9181). Weakened muscle power has been reported for two patients treated with melatonin 5 mg in the evening (62456). Some melatonin preparations contain contaminants that are associated with eosinophilia-myalgia syndrome (9715,9716).

Neurologic/CNS ...Orally, melatonin may cause migraine-like headache (1070,1077,15034,62384,62450,62710,62754,62804,62792,62914,88288,88293,88294,96318)(106297) or dizziness (62345,62384,62450,62456,62770,62784,62792,62804,62811,89510)(110297). Often these symptoms occur during the first few days of treatment and subside after a few days (62804). Melatonin may also cause drowsiness or fatigue when taken orally (1077,8273,15216,62384,62456,62784,62804,62811,88288,89510,96314,96316,96318,97446)(106293,106297). These symptoms appear to be more common if melatonin is taken in the morning or at very high doses (greater than 50 mg) (8269,62874). A case of excessive drowsiness has been reported when melatonin was combined with citalopram, nortriptyline, and oxycodone. Sedation improved with discontinuation of melatonin (96315). Indiscriminate use of melatonin may cause irregular sleep-wake cycles to occur (62998). Less commonly, melatonin may also cause behavior worsening (62811), confusion or disorientation (63014,63067), nighttime awakening (62710,62811), mood swings or agitation (96318), stereotypy (96318), excitement before bedtime (62811), nightmares or more intense dreams (62401,62462,62780,62784,88283), feelings of a "rocking" sensation (62155), or reduced alertness when taken orally.
A case of generalized epilepsy has reportedly occurred after treatment with melatonin for 4 months (9708). Also, some case reports raise concerns about increased risk of seizure with melatonin treatment, but conflicting evidence suggests that melatonin may decrease the risk of seizures (1699,8248,9695,9697,9744,9746,62123,62256,62384,62754)(63070,63071,89431). One patient experienced hyponatremia with confusion and seizures after taking prolonged-release melatonin 2 mg. However, malnutrition and cannabis abuse were also thought to contribute to this reaction (96321).
Although there is concern that melatonin might affect cognitive function in healthy adults, research in humans suggests that oral or topical melatonin do not impact most measures of cognitive function (97442,97448).

Psychiatric ...Orally, melatonin may cause mood changes, including dysphoria (sadness) (1764), dips in mood (62345,62450,62792), nervousness (62784), or transient depression (1077). Delusions and hallucinations have also been reported in clinical research (62347). An isolated incident of aggressiveness was also noted in a child diagnosed with attention deficit-hyperactivity disorder (ADHD) who took melatonin in combination with methylphenidate (9980). Severe irritability has been reported in two children with autism spectrum disorder who had abruptly discontinued melatonin due to the completion of a clinical trial (106293).

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