Cinnamon Bark 500 mg [Discontinued] by GNC Herbal Plus

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Amenorrhea. Although there has been interest in using oral cassia cinnamon for amenorrhea, there is insufficient reliable information about the clinical effects of cassia cinnamon for this purpose.
• Angina. Although there has been interest in using oral cassia cinnamon for angina, there is insufficient reliable information about the clinical effects of cassia cinnamon for this purpose.
• Common cold. Although there has been interest in using oral cassia cinnamon for the common cold, there is insufficient reliable information about the clinical effects of cassia cinnamon for this purpose.
• Diabetes. Several clinical trials have evaluated oral cassia cinnamon for type 2 diabetes, but results are conflicting. Details: Some clinical studies and meta-analyses of cassia cinnamon have found significant benefits in patients with diabetes (11347,17011,21914,21918,89646,89649,111692), while others have not (14344,16010,17689,21915,21916,89650). Results from meta-analyses are also mixed with respect to lowering fasting blood glucose and lipid levels (89647,108264). Meta-analyses including more than 1500 adults with type 2 diabetes show that taking cassia cinnamon 120 mg To 14.4 grams daily for 4-18 weeks reduces fasting blood glucose by an average of 25 mg/dL, total cholesterol by 16 mg/dL, low-density lipoprotein (LDL) cholesterol by 9 mg/dL, and triglycerides by 30 mg/dL, and increases high-density lipoprotein (HDL) cholesterol by 2 mg/dL (89647,111692). Analyses included studies examining either extract or powder, and two of the studies included used an unspecified type of cinnamon. In contrast, a more recent meta-analysis of studies limited to cassia cinnamon ground bark powder 1-2 grams daily for 40-90 days shows no benefit on fasting blood glucose or lipid levels (108264). Evidence regarding cassia cinnamon's effect on glycated hemoglobin (HbA1c) is mixed, with one meta-analysis of 15 clinical studies suggesting that it moderately lowers HbA1c, while other studies suggest that it does not, although some of the studies were too short to detect a change (89647,108264,111692). One meta-analysis found that cassia cinnamon was most beneficial for adults with HbA1c of 8% or higher (111692). The individual studies included in the meta-analyses were also small, and very heterogenous in relation to dose, duration, use of conventional medications, and diabetes control at baseline (89647,108264). Cassia cinnamon has also been evaluated in combination with other ingredients. A study in treatment-naïve adults newly diagnosed with type 2 diabetes shows that taking a combination product containing cassia cinnamon extract 100 mg, black seed extract, and ficin extract (NW Low-Glu) 4-5 times daily for 12 weeks reduces HbA1c by 0.6-0.8% and 2-hour postprandial glucose by 25-35 mg/dl when compared to baseline, with similar findings when compared with metformin. However, there were no notable differences in fasting blood glucose, insulin resistance, and beta cell function (111710). It is unclear if these effects are due to cassia cinnamon, other ingredients, or the combination. In patients with type 1 diabetes, clinical research shows that taking cassia cinnamon daily does not improve fasting blood glucose, HbA1c, insulin sensitivity, or the rate of hypoglycemic episodes (16010,89648).
• Diarrhea. It is unclear if oral cassia cinnamon is beneficial for diarrhea. Details: A moderate-sized clinical study in adults with diarrhea shows that taking cinnamon water extract 1200 mg twice daily for 8 weeks increases colonic transit time by about 10 hours but does not improve other symptoms of diarrhea including percentage of bowel movements with diarrhea, Bristol stool scale score, abdominal pain, bowel urgency, or abdominal distension when compared with placebo (111712).
• Dyslipidemia. It is unclear if oral cassia cinnamon is beneficial for dyslipidemia. Details: A meta-analysis of 12 clinical studies in adults with metabolic syndrome, polycystic ovary syndrome (PCOS), nonalcoholic fatty liver disease (NAFLD), type 2 diabetes, prediabetes, and overweight or obesity shows that taking cassia cinnamon daily for 2-4 months reduces total cholesterol by 7 mg/dL, triglycerides by 9 mg/dL, and low-density lipoprotein (LDL) cholesterol by 6 mg/dL but does not increase high-density lipoprotein (HDL) cholesterol. Subgroup analysis suggests that cassia cinnamon improves lipid profiles of Asian patients but not European or American patients. Additionally, higher doses appear to regulate lipid profiles better, and cassia cinnamon doses above 1.5 grams daily increase high-density lipoprotein cholesterol by about 2.5 mg/dL. Subgroup analysis also shows that cassia cinnamon only reduces triglycerides for patients with metabolic syndrome and increases HDL cholesterol for patients with PCOS but does not impact total cholesterol for those with type 2 diabetes (111709).
• Erectile dysfunction (ED). Although there has been interest in using oral cassia cinnamon for ED, there is insufficient reliable information about the clinical effects of cassia cinnamon for this purpose.
• Hypertension. Although there has been interest in using oral cassia cinnamon for hypertension, there is insufficient reliable information about the clinical effects of cassia cinnamon for this purpose.
• Impaired glucose tolerance (prediabetes). The effects of cassia cinnamon in patients with impaired glucose tolerance are unclear; results from clinical research are conflicting. Details: A small clinical study in patients with impaired glucose tolerance shows that taking cassia cinnamon powder 6 grams twice daily for 12 weeks does not improve fasting plasma glucose or insulin sensitivity when compared with placebo (96280). However, another clinical study in overweight or obese patients with impaired fasting blood glucose shows that taking a dried aqueous extract of cassia cinnamon 250 mg twice daily for 12 weeks reduces fasting blood glucose by about 12 mg/dL when compared with baseline, but does not affect fasting insulin levels (93118). Another preliminary clinical trial in overweight or obese patients with impaired glucose tolerance shows that taking two capsules of a specific combination product, (Glycabiane, PiLeJe) containing cassia cinnamon extract 228 mg, chromium chloride 10 mcg, and carnosine 100 mg per capsule, daily for 4 months decreases fasting blood glucose by 6.5 mg/dL but has no effect on glycated hemoglobin (HbA1c), insulin sensitivity, or body weight, when compared with placebo (94234). It is unclear whether these effects are due to cassia cinnamon, ingredients, or the combination.
• Mosquito repellent. It is unclear if topical cassia cinnamon is beneficial as a mosquito repellent. Details: Preliminary clinical research suggests that applying a cream containing cassia cinnamon oil 5% to the skin provides protection from mosquito bites. However, the repellency of this cream appears to decrease more quickly over time compared to MeiMei cream (containing citronella and geranium oils) and Repellan S aerosol (containing 19% N,N-diethyl-m-toluamide (DEET)) (59580).
• Muscle cramps. Although there has been interest in using oral cassia cinnamon for muscle cramps, there is insufficient reliable information about the clinical effects of cassia cinnamon for this purpose.
• Nausea and vomiting. Although there has been interest in using oral cassia cinnamon for nausea and vomiting, there is insufficient reliable information about the clinical effects of cassia cinnamon for this purpose.
• Obesity. It is unclear if oral cassia cinnamon is beneficial for weight loss. Details: A meta-analysis of 7 clinical studies shows that cassia cinnamon reduces body mass index (BMI) when compared with placebo (111692). However, preliminary clinical research in a small number of patients with overweight or obesity and impaired glucose tolerance shows that taking two capsules of a specific combination product (Glycabiane, PiLeJe) containing cassia cinnamon extract 228 mg, chromium chloride 10 mcg, and carnosine 100 mg per capsule, daily for 4 months does not decrease body weight, BMI, fat mass, or lipid levels when compared with placebo (94234). A very small clinical study in healthy adults shows that drinking a single dose of cinnamon infusion containing 2 grams of powdered cinnamon served along with breakfast does not increase energy expenditure, diet-induced thermogenesis, respiratory quotient, or lipid and carbohydrate oxidation and does not affect appetite responses including hunger, fullness, desire to eat, macronutrient intake, and food intake throughout the day when compared with control. Furthermore, cassia cinnamon intake reduces feelings of satiety and increases energy intake in the first meal after the intervention when compared with control (111707). The validity of these findings is limited by a lack of blinding.
• Polycystic ovary syndrome (PCOS). It is unclear if oral cassia cinnamon is beneficial for patients with PCOS. Details: A small observational study in adults with PCOS suggests that taking cinnamon 500 mg three times daily for 8 weeks is associated with decreased body weight, body mass index, insulin resistance, and testosterone but does not appear to alter levels of luteinizing hormone, follicle-stimulating hormone, dehydroepiandrosterone (DHEA), insulin, or lipids when compared with placebo (113514).
• Stroke. It is unclear if oral cassia cinnamon is beneficial for stroke prevention. Details: Preliminary clinical research in patients with a mild ischemic stroke or transient ischemic attack shows that taking cinnamon (Chinese herbal formula granules, Guangdong Yifang Pharmaceutical Co, Ltd) 5 grams with aspirin 100 mg daily for 90 days, starting within 24 hours of the ischemia, reduces the percentage of patients with a recurrent stroke to 3%, compared with 15% of those taking aspirin plus placebo. There were also modest improvements in levels of plasma lipids, glucose, and glycated hemoglobin, as well as a reduced likelihood of identifying unstable or severe plaques on carotid ultrasound (108265). The use of cassia cinnamon, specifically, was not confirmed; however, this species of cinnamon is commonly used in traditional Chinese medicine, as indicated in the study.
• Urinary incontinence. Although there has been interest in using oral cassia cinnamon for urinary incontinence, there is insufficient reliable information about the clinical effects of cassia cinnamon for this purpose. More evidence is needed to rate cassia cinnamon for these uses.

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POSSIBLY INEFFECTIVE

• Diabetes. Most research shows that oral Ceylon cinnamon does not benefit patients with type 2 diabetes. Details: Clinical research in adults with well-controlled type 2 diabetes shows that taking Ceylon cinnamon 1-9 grams orally daily for 2-3 months does not improve fasting blood glucose when compared with placebo or a control group (99436,99437,99439). However, one small clinical study in adults with poorly controlled type 2 diabetes despite treatment with metformin showed a trend toward improvement in fasting blood glucose. Taking Ceylon cinnamon 3 grams daily for 8 weeks reduced fasting blood glucose by 12 mg/dL, compared with an increase of 9 mg/dL in those taking placebo. Although this difference was not statistically significant, the study might not have been adequately powered to show a difference. Also, the 8-week duration of this study was too short to reliably assess the effect of Ceylon cinnamon on glycated hemoglobin (HbA1c) (99438). Conversely, a large study clinical study in patients with type 2 diabetes conducted in India shows that taking Ceylon cinnamon 1.5 grams daily for 4 months improves fasting blood glucose by 40 mg/dL and HbA1c by 1% when compared with placebo but does not significantly improve either outcome when compared to baseline (112422). However, it is unclear whether modifications to diabetes medications were allowed during the study.
• Obesity. Preliminary clinical research suggests that oral Ceylon cinnamon does not help with weight loss. Details: Preliminary clinical research shows that drinking black tea steeped with 3 grams of Ceylon cinnamon dried powder three times daily for 8 weeks does not affect weight, waist circumference, or blood pressure when compared with baseline or black tea alone in overweight patients with diabetes (95597). Other preliminary research shows that taking Ceylon cinnamon, titrated up from 85 mg to 500 mg, daily for 3 months has no effect on weight or body mass index, but may reduce hip circumference by 1.8 cm, when compared with baseline in healthy, mostly normal weight adults (97250).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Allergic rhinitis (hay fever). A nasal spray containing a Ceylon cinnamon extract might improve symptoms of allergic rhinitis. It is unclear if oral Ceylon cinnamon is beneficial. Details: Using a nasal spray containing a polyphenol-rich standardized extract of Ceylon cinnamon 1 mg/mL, twice daily in each nostril for 7 days, reduces the severity of nasal, eye, and nocturnal symptoms, and improves quality of life and work productivity when compared with placebo in people with seasonal allergic rhinitis who are not using any other medications for the condition (103169). One small clinical study in patients with seasonal allergic rhinitis shows that taking a specific combination product (ClearGuard, Access Business Group LLC) containing Ceylon cinnamon extract, acerola fruit concentrate, and powdered Spanish needles (Bidens pilosa) orally, 450 mg three times daily for 3 days, improves nasal symptoms 8 hours after, but not immediately following, a nasal allergen challenge when compared with placebo (23709).
• Chronic obstructive pulmonary disease (COPD). Ceylon cinnamon has only been studied in combination with other ingredients; its effect when used alone is unclear. Details: A moderate-sized clinical study in adults with COPD shows that taking a combination product containing extracts of Ceylon cinnamon, ginger, alpinia, cardamom, and saffron in honey 3 times daily for 8 weeks improves confidence in leaving home and the ratio of forced exploratory volume per second to forced vital capacity of the lungs (FEV1/FVC) when compared with placebo. However, the combination product does not improve most measures of respiratory function or symptoms such as cough, phlegm, chest tightness, dyspnea, reduced energy levels, sleeping disorders, or activity limitations when compared with placebo (111542). It is unclear if these effects are due to Ceylon cinnamon, other ingredients, or the combination.
• Common cold. Although there has been interest in using oral Ceylon cinnamon for the common cold, there is insufficient reliable information about the clinical effects of Ceylon cinnamon for this purpose.
• Denture stomatitis. It is unclear if topical Ceylon cinnamon is beneficial in patients with denture stomatitis. Details: A small clinical trial in patients with denture stomatitis shows that using 10 mL of a mouthwash, as well as a denture spray, containing Ceylon cinnamon essential oil three times daily for 15 days modestly reduces Candida measurements and improves the severity of stomatitis in the oral mucosa and dentures when compared with baseline (108262). The validity of these findings is limited by the lack of a comparator group.
• Diarrhea. Although there has been interest in using oral Ceylon cinnamon for diarrhea, there is insufficient reliable information about the clinical effects of Ceylon cinnamon for this purpose.
• Dysmenorrhea. It is unclear if oral Ceylon cinnamon is beneficial in patients with dysmenorrhea. Details: One preliminary clinical trial in adults with primary dysmenorrhea shows that taking Ceylon cinnamon orally 1 gram three times daily during the first 72 hours of menstruation over the course of two cycles decreases pain by 1.6 points on a 10-point visual analog scale when compared with placebo (99875). The use of a per-protocol analysis limits the validity of these results.
• Dyspepsia. It is unclear if oral Ceylon cinnamon is beneficial in patients with dyspepsia. Details: A small clinical trial in patients with functional dyspepsia shows that taking one capsule of Ceylon cinnamon oil, providing an unspecified dose, three times daily for 6 weeks does not improve symptoms of dyspepsia when compared with sesame oil as placebo (108263).
• Hypertension. It is unclear if oral Ceylon cinnamon is beneficial in patients with prehypertension. Details: A small clinical trial in patients with prehypertension shows that taking Ceylon cinnamon 500 mg three times daily for 90 days does not affect final blood pressure measurements when compared with placebo. However, there was a modest reduction in mean daytime systolic blood pressure when compared with placebo (108261).
• Impaired glucose tolerance (prediabetes). Although there has been interest in using oral Ceylon cinnamon for impaired glucose tolerance, there is insufficient reliable information about the clinical effects of Ceylon cinnamon for this purpose.
• Influenza. Although there has been interest in using oral Ceylon cinnamon for influenza, there is insufficient reliable information about the clinical effects of Ceylon cinnamon for this purpose.
• Intestinal parasite infection. Although there has been interest in using oral Ceylon cinnamon for intestinal parasite infection, there is insufficient reliable information about the clinical effects of Ceylon cinnamon for this purpose.
• Irritable bowel syndrome (IBS). Oral Ceylon cinnamon has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that taking a combination of powdered Ceylon cinnamon 1.5 grams, dried bilberry fruit 10 grams, slippery elm bark 4.5 grams, and agrimony 3 grams orally twice daily for 3 weeks increases the number of bowel movements and reduces symptoms such as abdominal pain, bloating, flatulence, and straining in patients with diarrhea-predominant IBS (35462).
• Migraine headache. It is unclear if oral Ceylon cinnamon is beneficial in patients with migraine headache. Details: Preliminary clinical research shows that taking Ceylon cinnamon powder orally 600 mg three times daily for 2 months, in addition to regular medications for migraine, decreases the frequency, severity, and duration of migraine attacks when compared with placebo (104520).
• Polycystic ovary syndrome (PCOS). It is unclear if oral Ceylon cinnamon is beneficial in patients with PCOS. Details: Taking Ceylon cinnamon orally 1.5 grams daily for 3 months in adults with PCOS does not appear to improve fasting insulin levels, fasting glucose levels, glycated hemoglobin, testosterone, lipid parameters, body weight, or body mass index when compared with placebo (97248). However, a meta-analysis of 5 low-quality studies shows that taking Ceylon cinnamon 0.5-1.5 grams daily for 8 weeks to 1 year reduces insulin resistance and fasting serum insulin levels (104518). Ceylon cinnamon has also been evaluated in combination with other ingredients. Some preliminary clinical research in overweight adults with PCOS shows that taking three tablets of a combination product containing extracts of Ceylon cinnamon, licorice root, peony root, and St. John's wort, providing the equivalent of 750 mg of dried herb for each ingredient, daily for 3 months, plus tribulus extract for 10 days during the follicular phase, in conjunction with lifestyle modification reduces the time between periods by around 43 days when compared with lifestyle modification alone. The rate of conception was four times higher with this combination when compared with control (97216). Another small clinical study shows that taking a mixture of Ceylon cinnamon, spearmint, ginger, and sweet orange daily for 3 months, in addition to clomiphene citrate for 5 days of each menstrual cycle, improves serum antioxidant levels, fasting blood glucose, and serum insulin levels when compared with clomiphene citrate alone. It is unclear whether these changes are associated with an increase in ovulation and pregnancy rates (103168). In both studies, it is unclear if the effects are related to Ceylon cinnamon, other ingredients, or to the combinations used.
• Premature ejaculation. Topical Ceylon cinnamon has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: In patients with premature ejaculation, applying a multi-ingredient cream (SS Cream) containing Panax ginseng root, Angelica root, Cistanches deserticola, Zanthoxyl species, Torlidis seed, clove flower, Asiasari root, Ceylon cinnamon, and toad venom to the glans penis one hour prior to intercourse and washing off immediately before intercourse improves ejaculatory latency when compared with placebo (2537). The effects of Ceylon cinnamon alone are unclear. More evidence is needed to rate Ceylon cinnamon for these uses.

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LIKELY SAFE ...when consumed in amounts commonly found in foods. Cassia cinnamon has Generally Recognized As Safe (GRAS) status in the US for use as a spice or flavoring agent (4912) ...when used orally and appropriately, short-term. Cassia cinnamon 1-2 grams daily has been used safely for up to 3 months (17011,21914). Cassia cinnamon 3-6 grams daily has been used safely for up to 6 weeks (11347,14344). Cassia cinnamon extract corresponding to 3 grams daily of cassia cinnamon powder has also been used safely for up to 4 months (21916).

POSSIBLY SAFE ...when used topically, short-term. Cassia cinnamon oil 5% cream applied topically to the legs has been used safely in one clinical trial (59580).

POSSIBLY UNSAFE ...when used orally in high doses, long-term. Some cassia cinnamon products contain high levels of coumarin. Coumarin can cause hepatotoxicity in animal models (15299,21920). In humans, very high doses of coumarin from 50-7000 mg daily can result in hepatotoxicity that resolves when coumarin use is discontinued (15302). In most cases, ingestion of cassia cinnamon will not provide a high enough amount of coumarin to cause significant toxicity; however, in especially sensitive people, such as those with liver disease, prolonged ingestion of large amounts of cassia cinnamon might exacerbate the condition.

CHILDREN: POSSIBLY SAFE
when used orally and appropriately, short-term. Cassia cinnamon 1 gram daily has been used safely in adolescents 13-18 years of age for up to 3 months (89648).

PREGNANCY AND LACTATION: LIKELY SAFE
when consumed in amounts commonly found in foods (4912). There is insufficient reliable information available about the safety of cassia cinnamon when used in medicinal amounts during pregnancy and breast-feeding. Stay on the safe side and stick to food amounts.

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LIKELY SAFE ...when consumed in amounts commonly found in foods. Ceylon cinnamon has Generally Recognized As Safe (GRAS) status in the US for use as a spice or flavoring agent (4912).

POSSIBLY SAFE ...when used orally and appropriately in medicinal amounts. Ceylon cinnamon 0.5-3 grams daily has been safely used in studies lasting up to 6 months (4,12,97248,97250,99874). ...when used as a mouth rinse for up to 15 days (92071). There is insufficient reliable information available about the safety of Ceylon cinnamon when used orally in greater amounts or for longer periods. Ceylon cinnamon contains trace amounts of coumarin (108260). In very high doses, coumarin can cause hepatotoxicity (15302). However, since the amount of coumarin in Ceylon cinnamon is negligible, it is unlikely to cause toxic effects (89652,92072,92073).

PREGNANCY: LIKELY SAFE
when consumed in amounts commonly found in foods (4912).

PREGNANCY: LIKELY UNSAFE
when used orally in amounts greater than those found in foods. Fetal abnormalities have been reported in animals (4,12).

LACTATION: LIKELY SAFE
when consumed in amounts commonly found in foods (4912). There is insufficient reliable information available about the safety of Ceylon cinnamon in amounts greater than those found in foods.

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ANTIDIABETES DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, cassia cinnamon may have additive effects with antidiabetes drugs.  Details Cassia cinnamon may lower blood glucose levels, and have additive effects in patients treated with antidiabetic agents (11347,17011,21914,21918,89649). Dose adjustments to diabetes medications might be necessary.

HEPATOTOXIC DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, large doses of cassia cinnamon might cause additive effects when used with hepatotoxic drugs.  Details There is some concern that ingesting large amounts of cassia cinnamon for an extended duration might cause hepatotoxicity in some people. Cassia cinnamon contains coumarin, which can cause hepatotoxicity in animal models (15299,21920). In humans, very high doses of coumarin from 50-7000 mg/day can result in hepatotoxicity that resolves when coumarin use is discontinued (15302,97249). Lower amounts might also cause liver problems in sensitive people, such as those with liver disease or those taking potentially hepatotoxic agents.

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ANTIDIABETES DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, Ceylon cinnamon may have additive effects with antidiabetes drugs.  Details Ceylon cinnamon may lower blood glucose levels (11247,11248,11973). Dose adjustments might be necessary.

ANTIHYPERTENSIVE DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, Ceylon cinnamon might have additive effects with antihypertensive drugs and increase the risk of hypotension.  Details Animal research shows that Ceylon cinnamon extract has vasorelaxant properties and reduces blood pressure in rat models of hypertension, possibly via inhibition of calcium influx through L-type voltage-sensitive channels (92085,92086).

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General ...Orally, cassia cinnamon appears to be well-tolerated. Significant side effects have not been reported in most patients.
Most Common Adverse Effects:
Topically: Burning mouth, stomatitis.

Dermatologic ...In one clinical trial, a rash was reported in one patient taking cassia cinnamon 1 gram daily for 90 days (17011).
In one case, a 58-year-old female with a documented allergy to topically applied cinnamic alcohol presented with eyelid dermatitis, which was found to be a manifestation of systemic contact dermatitis to cinnamon in the diet. Symptoms improved in two days and completely cleared five days after discontinuing the addition of cinnamon to food products (95599). In other case reports, two adults presented with allergic contact cheilitis following the ingestion of chai tea with cinnamon and yogurt with cinnamon. Cinnamon components were confirmed as the causative allergic agents with patch tests, and both cases of allergic contact cheilitis completely resolved upon cessation of the cinnamon-containing products (113516,113515).
Topically, allergic skin reactions and stomatitis from toothpaste flavored with cassia cinnamon have been reported (11915,11920). Intraoral allergic reactions with symptoms of tenderness and burning sensations of the oral mucosa have also been reported in patients using breath fresheners, toothpaste, mouthwash, candy, or chewing gum containing cinnamon, cinnamic aldehyde or cinnamic alcohol as flavoring agents. Glossodynia, or burning mouth syndrome, has also been reported in a 62-year-old female who ate apples dipped in cinnamon nightly (95598), and allergic contact dermatitis has been reported in a teenage female using a homemade cinnamon sugar face scrub (95596).

Endocrine ...In one clinical trial, a hypoglycemic seizure was reported in one patient taking cassia cinnamon 1 gram daily for 3 months. The event occurred one day after enrolling in the study (89648). It is unclear if cassia cinnamon caused this event.

Hepatic ...There is some concern about the safety of ingesting large amounts of cassia cinnamon for extended durations due to its coumarin content. Coumarin can cause hepatotoxicity in animal models (15299). In humans, very high doses of coumarin from 50-7000 mg/day can result in hepatotoxicity that resolves when coumarin is discontinued (15302). In clinical trials, taking cassia cinnamon 360 mg to 12 grams daily for 3 months did not significantly increase levels of aspartate transaminase (AST) or alanine transaminase (ALT) (21918,96280,108259). However, in one case report, acute hepatitis with elevated AST and ALT occurred in a 73-year-old female who started taking a cinnamon supplement (dose unknown) one week prior to admission. The cinnamon supplement was added on to high-dose rosuvastatin, which may have led to additive adverse hepatic effects. After discontinuing both products, liver function returned to normal, and the patient was able to restart rosuvastati without further complications (97249). In most cases, ingestion of cassia cinnamon won't provide a high enough amount of coumarin to cause significant toxicity; however, in especially sensitive people, such as those with liver disease or taking potentially hepatotoxic agents, prolonged ingestion of large amounts of cassia cinnamon might exacerbate the condition.

Immunologic ...An unspecified allergic reaction was reported in one patient taking cassia cinnamon 1 gram daily for 3 months (89648).

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General ...Orally, Ceylon cinnamon is generally well tolerated, and adverse reactions are uncommon.
Most Common Adverse Effects:
Orally: Bloating, dyspepsia, nausea.
Topically: Allergic dermatitis, irritation of mucous membranes and skin.

Dermatologic ...Orally, a case of systemic contact dermatitis has been reported in a patient who consumed cinnamon (type not specified) after being previously sensitized to cinnamyl alcohol via cutaneous exposure (95599). In a small study of oral Ceylon cinnamon, two patients reported itching (104520). In another small study, two patients reported rashes (108263).
Topically, cinnamon oil can cause skin irritation and allergic dermatitis, probably due to cinnamaldehyde which makes up 60% to 80% of cinnamon oil (2537,12635,92071,95596,95599). In one case report, a 16-year-old female experienced worsening dermatitis after using a homemade facial scrub containing cinnamon powder (type not specified). Symptoms improved after discontinuation of the scrub (95596). Several cases of intraoral allergic contact dermatitis have been reported in patients consuming cinnamon (type not specified) or using products containing constituents of cinnamon (95598).

Gastrointestinal ...Orally, gastrointestinal side effects such as heartburn, nausea, bloating, and dyspepsia have been reported (97250).

Hematologic ...Orally, a case of postoperative hemorrhage is reported in a 49-year-old patient after taking Ceylon cinnamon 1 tablespoon daily for 10 months. One day post-colectomy, the patient had an INR of 1.59 and intraabdominal bleeding that required exploratory laparotomies, blood transfusion, and fresh frozen plasma. Ultimately, the patient was discharged (112421).

Hepatic ...While there is concern about the coumarin content in cassia cinnamon increasing the risk for hepatic adverse effects and bleeding, the amount of coumarin in Ceylon cinnamon is negligible and unlikely to cause toxic effects (89652,92072,92073). In one case report, a 73-year-old female taking rosuvastatin for several months developed elevated liver function tests (LFTs), abdominal pain, nausea, and vomiting after taking cinnamon (unknown dose and type) for 7 days. The acute hepatitis and elevated LFTs resolved after stopping both cinnamon and rosuvastatin. The patient was later able to resume rosuvastatin without recurrence (97249).

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