Coffee Enema by Simply Young

LIKELY EFFECTIVE

• Mental alertness. Consumption of caffeinated coffee attenuates changes in alertness and cognitive capacity that occur throughout the day. It also improves mental performance and alertness following sleep deprivation. Details: Consumption of coffee and other caffeinated beverages seems to prevent a decline in alertness and cognitive capacity when consumed throughout the day (4221,4224). Caffeine can improve mental performance and alertness following prolonged sleep deprivation (10205). With respect to mental alertness while driving, some research shows that drinking a single cup of coffee containing 80 mg caffeine in 180 mL during a 15-minute rest after simulated driving for 2 hours reduces the amount of weaving and increases speed consistency in the 3rd and 4th hours of driving when compared with drinking decaffeinated coffee. Overall, the mental effort needed to drive, driving quality, and feelings of sleepiness appear to improve with caffeine consumption (93875).

POSSIBLY EFFECTIVE

• Diabetes. Population research has found that consumption of caffeinated coffee is associated with a reduced risk of developing type 2 diabetes. Consumption of coffee also seems to be associated with a reduced risk of mortality in patients with type 2 diabetes. Details: Population research suggests that consumption of caffeinated coffee is associated with a dose-dependent reduced risk of developing type 2 diabetes (11353,11731,14313,38174,91040,91055,111040). Some research suggests that increasing coffee consumption by 1 cup daily is associated with a 6% to 9% reduction in the incidence of type 2 diabetes (91040,91055). In North American adults, consuming 6 or more cups of coffee daily is associated with a 29% lower risk of developing diabetes in females and a 54% lower risk in males (11353). Research in European adults suggests that drinking 5-6 cups of coffee daily appears to reduce diabetes risk by 61% in females and 30% in males. Drinking 10 or more cups daily reduces diabetes risk by 79% in females and 55% in males (11731). Additional research suggests that drinking 3-4 cups of coffee daily reduces the risk of diabetes by 23% to 42% when compared with drinking just 1 cup daily (14343,38174). An analysis of these and other cohort studies involving over 457,000 patients suggests that drinking 3-4 cups of coffee or decaffeinated coffee daily is associated with a 25% to 35% reduced risk of type 2 diabetes when compared with drinking 2 cups or less daily. Each additional cup of coffee consumed each day is associated with a 5% to 10% reduction in the incidence of type 2 diabetes (97368). Some population research in patients with previous gestational diabetes has also investigated the association between consumption of coffee and risk of developing type 2 diabetes. Research suggests that consumption of at least 4 cups of caffeinated coffee daily is associated with a 54% reduced risk of type 2 diabetes when compared with drinking no coffee. There is no association between consumption of decaffeinated coffee and type 2 diabetes risk (111040). Coffee consumption has also been evaluated in patients with type 2 diabetes, with mixed findings. Most population research suggests that coffee consumption is associated with a reduced risk of mortality in patients with type 2 diabetes. In one meta-analysis of observational studies, drinking high amounts of coffee was associated with a 24% reduction in mortality risk, with a 9% reduction for each additional cup of coffee (104595). In another meta-analysis, drinking up to 4 cups of coffee daily was associated with a 19% reduction in all-cause mortality and a 34% reduction in coronary heart disease (CHD) mortality when compared with not drinking coffee. Reductions in cardiovascular disease (CVD) mortality were only significant when one large study was excluded during sensitivity analyses (107836). Results of individual studies are conflicting (37805,97374,104589,104594). Additionally, a cross-sectional study in older adults with type 2 diabetes has examined the relationship between coffee consumption and CVD risk factors. This study suggests that higher coffee consumption is associated with lower fasting plasma glucose and diastolic blood pressure and higher high-density lipoprotein (HDL) cholesterol and triglyceride levels (107825). Population research has examined the relationship between coffee consumption and change in kidney function in patients with type 2 diabetes. One study in patients with normal kidney function suggests that drinking any coffee is associated with up to a 25% prevention in kidney function decline when compared with no coffee consumption. Kidney function decline was based on estimated glomerular function rate (eGFR) measurements (111043).
• Heart failure. Consumption of caffeinated coffee seems to reduce the long-term risk of heart failure in those without cardiovascular disease (CVD) at baseline. Details: A meta-analysis of three large population studies, the Framingham Heart Study (FHS), Cardiovascular Heart Study (CHS), and Atherosclerosis Risk in Communities (ARIC) study, has found that increased daily coffee consumption is associated with a reduced long-term risk of heart failure in individuals without CVD at baseline. Drinking at least 2 cups of coffee daily is associated with a 29% to 31% reduced risk of heart failure. In the analysis, total caffeine intake, but not decaffeinated coffee intake, was associated with a reduced risk of heart failure (104597).
• Overall mortality. Consumption of coffee seems to reduce all-cause mortality. The effects of coffee on specific causes of mortality are variable. Details: Population research conducted in almost 4 million international individuals suggests that long-term, daily consumption of coffee is associated with an 8% to 28% reduction in all-cause mortality when compared to low or no coffee consumption (97373,97374,103997,103998,104594,104595,105308,105311,105314,107826)(107833,107839,111033), though not all research agrees (107822). The strongest association is seen for individuals consuming 2-4 cups of coffee daily and in never smokers. Most research suggests that consuming ground, instant, or decaffeinated coffee is associated with similar reductions in mortality (97373,97374,103997,103998,104594,104595,105308,105311,105314,107833)(111033). The use of sweeteners might affect the association of coffee consumption with all-cause mortality. Population research suggests that consumption of unsweetened coffee, in amounts ranging from any to up to 4.5 cups daily depending on type of coffee, is associated with a reduction in mortality of 14% to 39% when compared with no coffee consumption. Consumption of 1.5 to 3.5 cups of sugar-sweetened coffee is associated with a reduction in mortality of approximately 30%; however, this association does not occur with higher coffee intakes or the consumption of decaffeinated coffee. Any association between the consumption of artificially sweetened coffee and mortality is unclear. When subgroup analyses were conducted to determine the association of coffee consumption with cause-specific mortality, coffee consumption was associated with a reduction in cardiovascular mortality. In some analyses, this association is for ground or decaffeinated, but not sweetened, instant, or unfiltered, coffee (97373,97374,103997,103998,104594,104595,105308,105311,105314,107833)(111032). In another analysis, consumption of coffee was inversely associated with deaths from chronic respiratory diseases, diabetes, pneumonia and influenza, and intentional self-harm. There were no associations between coffee consumption and deaths from accidents, Alzheimer disease, or kidney disease (105311). The association between coffee consumption and cancer-related mortality is less clear. Although one large meta-analysis of population research suggests that consumption of approximately 2 cups of coffee daily is associated with a 4% decrease in cancer-related mortality, the results of individual studies are mixed. One large population cohort suggests that ground or instant caffeinated coffee consumption is associated with up to a 27% reduction in cancer mortality (97374), while other analyses show no association (97373,103994,105308,105311,107822). The reasons for this discrepancy are not clear but may be related to smoking status or use of sweeteners. In one meta-analysis, consumption of each additional cup of coffee daily is associated with a 2% decrease in cancer-related mortality in non-smokers, as opposed to an increased risk in smokers (105308). Other population research suggests that only intake of unsweetened coffee, and not sugar-or artificially-sweetened coffee, is associated with a reduced risk of cancer-related mortality (111032).
• Parkinson disease. Consumption of coffee seems to reduce the risk of developing Parkinson disease. This effect seems to be dose related in males, but not in females. Details: There is evidence that the risk of Parkinson disease is lower in people who consume caffeinated beverages such as coffee, tea, and cola. For males, the effect seems to be dose related. Males consuming the greatest amount of caffeinated coffee, 28 ounces (three to four cups) or a total of 421-2716 mg of caffeine from any source daily, seem to have the greatest reduction in risk. However, a significant reduction in risk exists even with consumption of as little as approximately 1-2 cups of coffee, or 124-208 mg of caffeine, daily (6022). In females, the effect does not seem to be dose related. Moderate consumption of caffeinated coffee, 1-3 cups daily, provides the greatest reduction in risk (1238). Coffee does not appear to provide additional protection from Parkinson disease in cigarette smokers (9236).
• Postoperative bowel function. Consumption of coffee seems to decrease the time to first stool and first flatus, and possibly time to discharge, after gynecological or colorectal surgeries. Details: Meta-analyses of mainly small clinical trials in patients who have undergone gynecological or colorectal surgeries show that drinking coffee decreases the time to the first stool and time to tolerating solid food by about 10 hours when compared with no treatment or drinking water or tea (103991,111035). Although one meta-analysis found that drinking coffee does not reduce the length of hospital stay (103991), other research shows that hospital stay is reduced by up to 1.5 days; however, sub-analyses suggest that benefit is limited to gynecological surgery and not colorectal surgery or caesarian section (97386,111035). Sub-analyses show that drinking coffee does not improve bowel function after caesarian section (103991,111035). Caffeinated coffee has been most commonly consumed as 100 mL three times daily starting after surgery and until the first stool. Some studies have used decaffeinated coffee (93876,97386,103991,111035,111039).
• Postoperative ileus. Consumption of coffee seems to reduce the risk of postoperative ileus. Details: A meta-analysis of mainly small clinical trials in patients who have undergone gynecological or colorectal surgeries shows that drinking coffee reduces the risk of postoperative ileus by 58% when compared with no treatment or drinking water or tea. Hospital length of stay was reduced by approximately 1.5 days. However, sub-analyses suggest that this benefit is limited to patients following cesarean section or gynecological surgery, and not colorectal surgery (111035).

POSSIBLY INEFFECTIVE

• Esophageal cancer. Consumption of coffee does not seem to be associated with a reduced risk of esophageal cancer. Details: Population research has found that coffee intake is not associated with the incidence of esophageal cancer (9222,90186,100874). However, subgroup analyses have found coffee consumption may be associated with a reduced risk of esophageal cancer in patients from East Asia (100874).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Attention deficit-hyperactivity disorder (ADHD). Although there has been interest in consuming coffee for ADHD, there is insufficient reliable information about the clinical effects of coffee for this purpose.
• Atherosclerosis. It is unclear if consuming coffee is beneficial for atherosclerosis. Details: Population research has found that drinking coffee is not associated with prevalent coronary-artery calcium, a subclinical marker of atherosclerosis, in patients without known coronary heart disease (97371).
• Atrial fibrillation. It is unclear if consuming coffee affects the risk of atrial fibrillation. The available research is conflicting. Details: A meta-analysis of observational research suggests that coffee intake is not associated with the incidence of atrial fibrillation (100860). However, a more recent observational study suggests that drinking at least 1 cup of coffee per week is associated with a 40% increased risk of atrial fibrillation, with the highest incidence of atrial fibrillation occurring in adults consuming at least 6 cups daily. A sub-analysis found that this association remained only for White participants and not other ethnicities (111042). This study was limited by its relatively small sample size and a higher than general proportion of smokers. Some observational research in elderly persons following the Mediterranean diet suggests that consuming 4-28 cups of coffee monthly (up to 1 cup daily) is associated with a lower risk of atrial fibrillation when compared with 3 cups or less monthly. Consuming more than 1 cup of coffee daily was not associated with reduced risk (103988). However, it is unclear if this association was due to moderate coffee consumption, the Mediterranean diet, or other, unidentified factors.
• Bladder cancer. Population research suggests that coffee consumption does not reduce the risk of bladder cancer. Details: Although earlier evidence has been conflicting (97375,97376), the most comprehensive analysis of cohort and case control studies has found that coffee consumption is not associated with bladder cancer risk. In subgroup analyses of females, males, or non-smokers, coffee did not affect risk (103992).
• Brain tumor. It is unclear if consuming coffee reduces the risk of brain cancer. Details: Observational research has found that consumption of coffee is associated with a lower risk of brain cancer in Asian populations, but not in American populations (100870).
• Breast cancer. Population research suggests that coffee consumption does not reduce the risk of breast cancer. Details: Population research has found that consumption of coffee is not associated with a reduced incidence of breast cancer (9235,97377,107823).
• Cancer. Although there has been interest in using rectal coffee enemas for the treatment of cancer, there is insufficient reliable information about the clinical effects of coffee for this purpose.
• Cardiovascular disease (CVD). Some population research has found that drinking coffee is associated with a reduced risk of heart failure, but not with a reduced risk of major adverse cardiac events, coronary heart disease, or CVD in general. In patients with a history of CVD, coffee consumption may reduce CVD-related mortality. However, at least some evidence suggests that there is a J-shaped association between coffee consumption and the risk of acute coronary syndromes. Details: A meta-analysis of three large population studies, the Framingham Heart Study (FHS), Cardiovascular Heart Study (CHS), and Atherosclerosis Risk in Communities (ARIC) study, suggests that increased daily coffee consumption is associated with a reduced long-term risk of heart failure in individuals without CVD at baseline. Drinking at least 2 cups of coffee daily is associated with a 29% to 31% reduced risk of heart failure. However, there was no association between coffee consumption and risk of stroke, coronary heart disease, or CVD in general. In the analysis, total caffeine intake, but not decaffeinated coffee intake, was associated with a reduced risk of heart failure (104597). In one cohort study, there was no association between past coffee-drinking and the prevalence of having coronary heart disease as determined by a coronary angiography (104588). However, a large population study suggests that drinking up to 5 cups daily of instant, ground, or decaffeinated coffee is associated with a reduced risk of incident CVD, including coronary heart disease, cardiac failure, and/or ischemic stroke, of approximately 11% (111033). The association between coffee consumption and arrhythmia has also been investigated. In one population study, there was a 3% reduced risk of arrhythmia for each additional cup of habitual coffee consumed. Similar effects were seen when atrial fibrillation and supraventricular tachycardia, but not ventricular tachycardia, were independently analyzed (105310). More recent population research suggests that consuming 1-5 cups daily of ground or instant coffee, but not decaffeinated coffee, is associated with up to a 17% reduced risk of arrhythmia when compared with not consuming coffee. Intake of more than 5 cups was no longer associated with a reduced risk of arrhythmia (111033). Some population research suggests a J-shaped association between regular coffee consumption and the risk of developing acute coronary syndromes. Moderate consumption of less than 300 mL daily (about 1.3 cups) was associated with a lower risk of developing acute coronary syndromes, whereas regular consumption of 300 mL daily or more was associated with an increased risk (11318). However, other population research in people without a history of CVD suggests that drinking more than 6 cups of coffee daily does not appear to be associated with an increased risk of developing coronary heart disease (14343). The association between coffee consumption and CVD-related mortality has also been evaluated in people with CVD. Population research suggests that coffee consumption is associated with a reduction in CVD-related mortality. In some analyses, this association is for ground or decaffeinated coffee only (97373,97374,103997,103998,104594,104595,105308,105311,105314). A meta-analysis of a small number of population studies suggests that consuming coffee for at least 1 year after a myocardial infarction (MI) is associated with a small reduction in risk of CVD-related mortality and no increased risk of all-cause mortality or major cardiac events, such as a recurrent MI or stroke (104882). In patients with a history of acute coronary syndrome, including acute MI or unstable angina, consumption of 1-3 cups of coffee daily is associated with a reduced risk of overall mortality over a 4-year period, especially in never or former smokers. However, in those who are current smokers, consuming more than 3 cups daily is associated with a more than 2-fold increased risk of overall mortality (8533,105313).
• Chronic kidney disease (CKD). It is unclear if consuming coffee is beneficial for the prevention or management of CKD. Details: A small meta-analysis of population research has found that coffee consumption is associated with a 14% reduced incidence of CKD; drinking at least 2 cups daily seems to have the most benefit. Coffee consumption is also associated with an 18% reduced incidence of progression to kidney failure, as well as lower odds of having albuminuria. In addition, coffee consumption is associated with a reduced risk of CKD-related death, with at least 4 cups daily providing the most benefit when compared with drinking no coffee (104586). The validity of these findings is limited by the heterogeneous definitions of CKD, kidney failure, and albuminuria in the individual studies, as well as the comparisons of coffee consumption.
• Cognitive function. It is unclear if consuming coffee is beneficial for cognitive function. Details: Some population research has found that higher lifetime coffee consumption might positively affect cognitive function among females aged 80 years or older (10620). Additionally, a small clinical study in healthy adults shows that consuming a single dose of regular coffee 220 mL containing 100 mg of caffeine improves reaction time and working memory, but not episodic memory, when compared with placebo (100864).
• Colorectal cancer. It is unclear if consuming coffee is beneficial for the prevention or treatment of colorectal cancer. Details: A meta-analysis of cohort studies conducted in North America and Europe suggests that there is no association between coffee intake and the incidence of colorectal cancer (97385). However, population research conducted in Japan and Korea suggests that drinking coffee is associated with a lower risk of colorectal cancer, with the greatest reduction seen in patients consuming 3 or more cups of coffee daily (9222,97384,107832,111041). In one study, risk reduction increased from 32% to 78% when adjusted for the use of coffee additives, including cream and sugar (107832). In addition, drinking coffee is associated with a reduced risk of disease progression and death in patients with advanced or metastatic colorectal cancer. Each additional cup daily is associated with a 5% reduced risk of cancer progression and a 7% reduced risk of death. The greatest benefits were associated with drinking at least 4 cups daily when compared with no coffee consumption (104591).
• Constipation. Although there has been interest in consuming coffee for constipation, there is insufficient reliable information about the clinical effects of coffee for this purpose.
• Dementia. It is unclear if consuming coffee is beneficial for preventing dementia. Details: One meta-analysis of observational studies including nearly 329,000 adults has found that drinking coffee is not associated with a lower risk of dementia or Alzheimer disease (100866). Conversely, other observational research has found evidence of benefit, but results are conflicting. A meta-analysis of observational studies in nearly 334,000 adults has found a reduced risk of any cognitive deficit (including mild cognitive impairment and dementia) or dementia alone in those drinking less than 2.8 or 2.3 cups of coffee daily, respectively, when compared with not drinking coffee (107829). The validity of these findings is limited by a lack of discussion of heterogeneity and variability in sensitivity analyses. An individual observational study in nearly 14,000 adults has found that coffee and caffeine consumption is associated with dose-dependent reductions in dementia risk, especially in males, and that drinking at least 3 cups of coffee daily is associated with a 50% lower risk of dementia when compared with not drinking coffee (107841). Coffee consumption has also been studied in combination with tea. An observational study has found that drinking 0.5-1 cup of coffee with at least 4 cups of tea or 2-3 cups of coffee and tea each daily is associated with a 28% to 30% reduced risk of dementia when compared with not drinking coffee and tea (107204).
• Depression. It is unclear if consuming coffee is beneficial for reducing the risk of depression. Details: Observational research has found that higher coffee consumption is associated with a 24% lower risk of depression when compared with lower coffee consumption. Drinking 400-600 mL of coffee daily is associated with 16% lower risk of depression when compared with not consuming coffee (100863).
• Endometrial cancer. It is unclear if consuming coffee is beneficial for the prevention of endometrial cancer; the available research is conflicting. Details: One meta-analysis of prospective cohort studies suggests that drinking coffee is associated with a dose-dependent reduction in the risk of endometrial cancer. Increasing coffee consumption by 4 cups daily is associated with a 20% reduction in endometrial cancer risk (97381). Another meta-analysis of population research suggests that the highest intake of caffeinated coffee, but not decaffeinated coffee, is associated with a 34% reduced risk of endometrial cancer when compared with the lowest. A sub-analysis suggests that this association is limited to individuals with a high body mass index (111036). In contrast, earlier meta-analyses and one large prospective cohort study conducted in the United Kingdom suggests that drinking coffee is not associated with a reduced risk of endometrial cancer in general; however, there may be some protection in obese females drinking at least 2 cups of caffeinated coffee daily (93873,97381,97382).
• Fractures. It is unclear if consuming coffee is beneficial for fracture prevention. Details: A meta-analysis of observational research suggests that the highest intake of coffee is not associated with a reduced odds of fracture when compared with the lowest. However, any association may be dependent on the dose of coffee and/or the location of research. A dose-response meta-analysis suggests that consuming 0.5 to 4 cups daily, but not higher amounts, is associated with a small reduction in the incidence of hip fracture when compared with no coffee consumption. Additional sub-analyses suggest that while the highest coffee consumption was associated with a 25% reduced risk of fracture in studies conducted in Europe and North America, the opposite is true in studies conducted in Asia where the risk is increased by 37% (111034).
• Gallbladder disease. Population research suggests that consuming coffee may reduce the risk of developing symptomatic gallstone disease. Details: Population research has found that the consumption of caffeinated beverages, including coffee, that provide at least 400 mg of caffeine (two or more cups of coffee) daily is associated with a significantly reduced risk of developing symptomatic gallstone disease (3345,8032). The effect seems to be dose-dependent; consumption of 800 mg caffeine (four or more cups of coffee) daily is associated with the greatest reduction in risk (3345).
• Gastric cancer. It is unclear if consuming coffee reduces the risk of gastric cancer. Details: Overall, meta-analyses of observational research suggest that coffee consumption does not affect gastric cancer risk. However, subgroup analyses of patients living in the United States suggest that consuming coffee is associated with an increased risk of gastric cancer (100873,111038). One sub-analysis suggests that consuming 6.5 or more cups of coffee daily was associated with a 36% greater risk of gastric cancer (100873).
• Gout. It is unclear if consuming coffee is beneficial for preventing gout. Details: Epidemiological research has found that the risk of developing gout over a 12-year period is 40% lower in males aged 40-75 years who drink 4-5 cups of caffeinated coffee daily, compared with those who don't drink coffee. In people who drink 6 cups or more daily, the risk of developing gout is 59% lower. Drinking decaffeinated coffee is also associated with a reduced risk of developing gout, but the risk reduction is more modest than with caffeinated coffee (15540).
• Headache. Although caffeine is an established treatment for certain types of headache, there is insufficient reliable information about the clinical effects of coffee, specifically, for this purpose.
• Hearing loss. It is unclear if consuming coffee is beneficial for hearing loss. Details: Population research has found that consuming at least one cup of coffee daily is associated with a reduced risk of hearing impairment in males, but not females, when compared with less than one cup of coffee daily. In males, each additional cup consumed daily was associated with a 15% lower risk of hearing impairment (104592).
• Hepatitis B. It is unclear if consuming coffee is beneficial for hepatitis B. Details: Population research in patients being treated for chronic hepatitis B suggests that drinking at least 3 cups of coffee a day is associated with a reduced risk of having liver fibrosis when compared to not consuming coffee. However, this association was not present in untreated patients (111044). This study is limited by its cross-sectional design and use of blood markers, rather than the gold standard liver biopsy, for diagnosing fibrosis.
• Hyperlipidemia. It is unclear if consuming caffeinated coffee is beneficial for hyperlipidemia. Details: A meta-analysis of small, randomized, controlled trials shows that consuming caffeinated coffee for up to about 11 weeks reduces total cholesterol by 8 mg/dL, low-density lipoprotein (LDL) cholesterol by 5 mg/dL, and triglycerides by 13 mg/dL when compared with a control group. These effects appear to be dose-dependent, with the greatest reduction observed in individuals consuming 6-8 cups of coffee daily. Every additional cup of caffeinated coffee consumed daily is associated with a 3-4 mg/dL additional reduction in total and LDL cholesterol and a 6-7 mg/dL additional reduction in triglyceride levels. Decaffeinated coffee had no effect on any markers of cholesterol (97370). However, population research has found that coffee consumption is associated with slightly higher total cholesterol, LDL cholesterol, and triglyceride levels when compared with no coffee consumption (104590).
• Hypertension. Epidemiologic research suggests that consuming coffee reduces the risk of developing hypertension. Details: Some epidemiological research suggests that coffee consumption might reduce the risk of developing hypertension. A meta-analysis of epidemiologic research suggests that long-term coffee intake is associated with a modest 9% reduction in the risk of developing hypertension. However, smoking may diminish any potential benefit (97372). This analysis did not investigate the likelihood of a dose-response relationship and did not adjust for smoking status. Another epidemiologic study in a Brazilian population that did adjust for sociodemographic factors such as smoking suggests that drinking 1-3 cups of coffee daily is associated with a reduced risk of hypertension by about 18% when compared with never or almost never drinking coffee. Drinking more than 3 cups of coffee did not impact risk (103993). However, this study defined 1 cup of coffee as 50 mL; it is unclear how this intake compares with typical use in other countries. The best evidence comes from a meta-analysis of observational research which suggests that coffee intake was not associated with hypertension risk. However, coffee intake was associated with a modest reduction in hypertension risk in studies conducted in the United States (111037). In patients with hypertension, a meta-analysis of epidemiologic research suggests that habitual coffee intake is not associated with the risk of developing CVD (105312). However, other prospective population research in patients with severe hypertension, but not mild hypertension, suggests that drinking at least two cups of coffee daily is associated with a 2-fold increase in CVD mortality compared with non-coffee drinkers (111027).
• Hypotension. It is unclear if consuming caffeinated coffee is beneficial in older adults with postprandial hypotension. Details: Preliminary clinical research in older adults with postprandial hypotension shows that consuming caffeinated beverages like coffee seems to increase blood pressure (11835).
• Kidney failure. It is unclear if consuming coffee is beneficial for preventing progression to kidney failure or reducing the risk of chronic kidney disease (CKD)-related death. Details: A small meta-analysis of population research has found that coffee consumption is associated with an 18% reduced incidence of progression from CKD to kidney failure. Coffee consumption is also associated with a reduced risk of CKD-related death, with at least 4 cups daily providing the most benefit when compared with not drinking coffee (104586). This analysis is limited by the heterogeneous definitions of CKD and kidney failure in the individual studies, as well as the comparisons of coffee consumption.
• Liver cancer. It is unclear if consuming coffee reduces the risk of liver cancer. Details: A meta-analysis of observational research in approximately 2.5 million adults in Asia, North America, and Europe suggests that consuming at least 1 cup of coffee daily is associated with a 27% to 48% reduced risk of liver cancer (111016). An earlier meta-analysis of observational research suggests that regular coffee consumption is associated with a 31% lower risk of hepatocellular carcinoma when compared with no consumption. Higher coffee consumption seems to have a greater preventative effect when compared with lower coffee consumption (103989).
• Liver disease. It is unclear if consuming coffee reduces the risk of chronic liver disease. Details: Observational research has found that regular coffee consumption is associated with a 38% lower risk of chronic liver disease when compared with no consumption. Higher coffee consumption seems to have a greater preventative effect when compared with lower coffee consumption (100862).
• Lung cancer. It is unclear if consuming caffeinated coffee reduces the risk of lung cancer; the available research is conflicting. Details: Epidemiological research has found that males who consume a higher amount of dietary phytoestrogens, such as the lignan precursors found in coffee and tea, have up to a 27% lower risk of developing lung cancer when compared with those who consume smaller amounts (13190). However, conflicting evidence suggests that people who consume 2-4 or more cups of caffeinated coffee daily have a significantly increased risk of developing lung cancer (13191,90177). But drinking decaffeinated coffee seems to be associated with a decreased risk of lung cancer (13191).
• Melanoma. It is unclear if consuming coffee reduces the risk of malignant melanoma. Details: Population research has found that high coffee intake is associated with a 19% to 25% reduction in the risk of malignant melanoma when compared with low consumption. However, after adjusting for confounders, most data show no significant reduction. Drinking decaffeinated coffee is not associated with a reduced incidence of malignant melanoma (97378,97379).
• Metabolic syndrome. It unclear if consuming decaffeinated coffee is beneficial in patients with metabolic syndrome. Details: A meta-analysis of mostly small randomized controlled studies in patients with metabolic syndrome shows that consumption of decaffeinated coffee modestly reduces systolic and diastolic blood pressure when compared with control. The validity of these findings is limited by the high heterogeneity and small size of the included studies (107830).
• Nonalcoholic fatty liver disease (NAFLD). Observational research suggests that consuming coffee may reduce the risk of NAFLD. Observational and clinical research on liver fibrosis is conflicting. Details: A meta-analysis of observational research in over 50,000 patients has found that drinking 1-2 cups of coffee daily does not affect NAFLD incidence when compared with drinking less than 1 cup of coffee. However, drinking more than 3 cups of coffee daily was associated with a reduced risk of NAFLD when compared with less than 2 cups daily (103990). Other observational research has found a reduced risk of NAFLD and/or fibrosis in those who drink coffee when compared with those who do not drink coffee (100872,107831). However, the validity of these findings is limited by a relatively small population size and the lack of dose-response analyses. Two of the primary bioactive constituents of coffee, caffeine and chlorogenic acid, also have been evaluated. A small study in patients with NAFLD and type 2 diabetes shows that taking caffeine 200 mg and/or chlorogenic acid 200 mg for 6 months has no effect on the reduction of hepatic fat and fibrosis when compared with placebo (107835).
• Nonmelanoma skin cancer. It is unclear if consuming caffeinated coffee reduces the risk of nonmelanoma skin cancer. Details: Population research has found that the highest intake of coffee or caffeine is associated with an 18% reduction in nonmelanoma skin cancer risk when compared with the lowest intake. However, the benefit appears to be limited to the incidence of basal cell carcinoma. Drinking decaffeinated coffee is not associated with a reduced incidence of nonmelanoma skin cancer. The effect, if any, appears to be due to caffeine rather than coffee (97380).
• Obesity. It is unclear if consuming coffee is beneficial for weight loss in patients who are overweight or obese; the available research is conflicting. Details: Some clinical research in males who are overweight or obese and are receiving dietary counseling shows that taking coffee mannooligosaccharides 2 grams twice daily for 12 weeks reduces body weight by 6%, compared with 2.3% with placebo. The product also reduces body fat in males, but not females (93877). Additional clinical research in patients with pre-obesity shows that drinking a dark roast coffee 500 mL daily, enriched with N-methylpyridinium ions, for 4 weeks results in weight loss of 3.5%, compared with 0% with a light roast coffee enriched in chlorogenic acids. The dark roast coffee appears to reduce caloric intake (93874). However, other clinical research in adults who are overweight or obese shows that drinking caffeinated or decaffeinated coffee 885 mL daily for 8 weeks does not appear to improve glycemic control or reduce weight (93879).
• Osteoporosis. It is unclear if consuming coffee is beneficial for osteoporosis prevention. Details: A meta-analysis of observational research suggests that the highest coffee consumption is associated with a 21% reduced odds of osteoporosis when compared with the lowest (111034).
• Pancreatitis. It is unclear if consuming coffee reduces the risk of pancreatitis. Details: Observational research has found that drinking three or more cups of coffee daily is associated with a 22% lower risk of pancreatitis when compared with drinking less coffee (100871).
• Pharyngeal cancer. It is unclear if consuming coffee reduces the risk of pharyngeal cancer. Details: Observational research has found that high coffee consumption is associated with a 28% reduced odds of pharyngeal cancer when compared with low coffee consumption (100869).
• Pregnancy-induced hypertension. It is unclear if consuming coffee reduces the risk of pregnancy-induced hypertension. Details: A large prospective cohort study in pregnant patients in Japan has found that the highest total caffeine intake is associated with a 26% increased risk of pregnancy-induced hypertension when compared with no intake, but that a higher coffee intake (at least 2 cups daily) is associated with a 21% reduced risk of pregnancy-induced hypertension when compared with no intake, even when adjusted for total caffeine intake (107827). The validity of these findings may be limited by the fact that detailed information on proteinuria and hypertension were unavailable.
• Pneumonia. It is unclear if consuming coffee is beneficial for reducing the risk of pneumonia. Details: A case-control study in elderly patients has found a 50% reduced risk of pneumonia in those consuming 2 or more cups of coffee daily over the past month (107840). The validity of this finding may be limited by differences in the baseline characteristics between the matched control subjects and the cases, specifically the higher prevalence of hypertension and diabetes in the control group.
• Prostate cancer. Population research has found that coffee consumption is associated with a modestly reduced risk of prostate cancer. Details: Although some individual studies disagree (107834), population research has found that the highest coffee consumption is associated with a small reduction in the risk of prostate cancer when compared with the lowest consumption (97383,97384,104587). Sub-analyses show that coffee consumption is associated with a 7% reduced risk of localized, but not advanced or fatal, prostate cancer (97383,97384,104587).
• Stroke. It is unclear if coffee consumption, alone or in combination with tea, is beneficial for stroke, post-stroke dementia, all-cause mortality, or stroke-related mortality. The available research is conflicting. Details: Several meta-analyses of population research in patients with and without cardiovascular disease (CVD) have found no association between coffee consumption and risk of stroke (104597,104882). However, another meta-analysis of population research and an individual observational study have found that coffee consumption (e.g., 2-3 cups of coffee daily) is associated with an 8% to 12% reduced risk of stroke, especially ischemic stroke, when compared with no consumption (107204,107828). The validity of the findings from the meta-analysis is limited by the lack of a dose-response analysis. Additionally, this analysis found that consumption of 2-3 cups of coffee daily is associated with a 20% reduced risk of post-stroke dementia when compared with not drinking coffee (107204). The consumption of coffee in combination with tea has also been evaluated. An observational study has found that consumption of 2-3 cups daily each of coffee and tea, including black tea, is associated with a 32% reduced risk of stroke when compared with not drinking coffee and tea. Additionally, consumption of 0.5-1 cup of coffee and 2-3 cups of tea, including black tea, daily is associated with a 50% reduced risk of post-stroke dementia when compared with not drinking coffee and tea (107204). Coffee consumption has also been evaluated for its effects on stroke-related and all-cause mortality. One observational study has found that consumption of 1-2 cups of coffee daily is associated with a 50% reduced risk of stroke-related mortality (107822). However, another observational study in patients with a history of stroke has found no association between coffee consumption and all-cause mortality (107839).
• Thyroid cancer. It is unclear if consuming coffee reduces the risk of thyroid cancer. Details: Population research has found that high coffee consumption is associated with a 25% lower risk of thyroid cancer when compared with low consumption. Every additional cup of coffee was associated with a 5% reduction in risk (103996). More evidence is needed to rate coffee for these uses.

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LIKELY SAFE ...when used orally and appropriately. Drinking decaffeinated coffee or coffee containing caffeine in low to moderate amounts is safe (15,98806). According to a review by Health Canada, and a subsequent large meta-analysis conducted in the US, drinking up to 4 cups of coffee daily providing caffeine 400 mg daily is not associated with significant adverse cardiovascular, bone, behavioral, or reproductive effects in healthy adults (11733,98806). The US Dietary Guidelines Advisory Committee states that there is strong and consistent evidence that consumption of beverages such as coffee that contain caffeine 400 mg daily is not associated with increased risk of major chronic diseases, such as cardiovascular disease or cancer, in healthy adults (98806).

POSSIBLY UNSAFE ...when used orally in excessive amounts. Acute use of high doses of caffeine (more than 400 mg per day), which is found in more than 4 cups of caffeinated coffee, has been associated with significant adverse effects such as tachyarrhythmia and sleep disturbances (11832). Drinking caffeinated coffee in amounts greater than 6 cups per day (about 600 mg caffeine) short-term or long-term can also cause caffeinism, with symptoms of anxiety possibly progressing to delirium and agitation. Chronic use of caffeine, especially in large amounts, can sometimes produce tolerance, habituation, and psychological dependence (3719). Abrupt discontinuance of caffeine can cause physical withdrawal symptoms (11733). Keep in mind that only the amount of ADDED caffeine must be stated on product labels. The amount of caffeine found in ingredients such as coffee, which naturally contains caffeine, does not need to be provided. This can make it difficult to determine the total amount of caffeine in a given product. ...when used rectally as an enema. Coffee enemas have been linked to cases of severe electrolyte abnormalities and septicemia leading to severe side effects including death (3026,3347,3349,6652).

CHILDREN: POSSIBLY SAFE
when coffee containing caffeine is consumed orally in moderate amounts. Oral intake of caffeine in doses of less than 2.5 mg/kg daily is not associated with significant adverse effects in children and adolescents (11733,98806). However, higher doses should be avoided. The adverse effects typically associated with caffeine-containing coffee are usually more severe in children than adults (11733).

PREGNANCY: POSSIBLY SAFE
when used orally in moderate amounts. Intake of caffeine from coffee and other sources should be monitored during pregnancy. Caffeine crosses the human placenta, but is not considered a teratogen. Fetal blood and tissue levels are similar to maternal concentrations (4260). The use of caffeine during pregnancy is controversial; however, moderate consumption has not been associated with clinically important adverse fetal effects (2708,2709,2710,2711,9606,11733,16014,16015). However, some research has also found that intrauterine exposure to even modest amounts of caffeine, based on maternal blood levels during the first trimester, is associated with a shorter stature in children ages 4-8 years (109846). In some studies, consuming amounts over 200 mg daily has been associated with a significantly increased risk of miscarriage (16014). This increased risk may be most likely to occur in people with genotypes that confer a slow rate of caffeine metabolism (98806). According to a review by Health Canada, and a subsequent large meta-analysis conducted in the US, most healthy pregnant patients can safely consume caffeine in doses up to 300 mg daily without an increased risk of spontaneous abortion, stillbirth, preterm birth, fetal growth retardation, or congenital malformations (11733,98806). Advise patients to keep caffeine consumption below 300 mg daily during pregnancy. This is similar to the amount of caffeine in about 3 cups of coffee. Keep in mind that only the amount of ADDED caffeine must be stated on product labels. The amount of caffeine found in ingredients such as coffee, which naturally contains caffeine, does not need to be provided. This can make it difficult to determine the total amount of caffeine in a given product.

PREGNANCY: POSSIBLY UNSAFE
when caffeinated coffee providing more than 300 mg of caffeine daily is consumed orally. Caffeine from coffee crosses the placenta, producing fetal blood concentrations similar to maternal levels (4260). Consumption of caffeine in amounts over 300 mg daily is associated with a significantly increased risk of miscarriage in some studies (16014,98806). Advise patients to keep caffeine consumption from all sources below 300 mg daily during pregnancy. This is similar to the amount of caffeine in about 3 cups of coffee. High doses of caffeine throughout pregnancy have resulted in symptoms of caffeine withdrawal in newborn infants (9891). High doses of caffeine have also been associated with spontaneous abortion, premature delivery, and low birth weight (2709,2711). Drinking more than 6 cups of coffee daily increases the risk of spontaneous abortion (2709). Drinking 8 or more cups of coffee daily doubles the risk of stillbirth when compared with those who do not drink coffee during pregnancy (10621).

LACTATION: POSSIBLY SAFE
when used orally. Drinking one or two caffeine-containing beverages daily during lactation is not associated with unacceptable levels of caffeine in human milk (11734).

LACTATION: POSSIBLY UNSAFE
when used orally in large amounts. Caffeine from coffee can cause wakefulness or irritability in breast-fed infants. Caffeine can also cause feeding intolerance and gastrointestinal irritation in infants (6026).

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ADENOSINE (Adenocard) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, coffee might decrease the vasodilatory effects of adenosine and interfere with its use prior to stress testing.  Details Coffee contains caffeine. Caffeine is a competitive inhibitor of adenosine at the cellular level (38172). However, caffeine does not seem to affect supplemental adenosine because high interstitial levels of adenosine overcome the antagonistic effects of caffeine (11771). It is recommended that methylxanthines such as caffeine, as well as methylxanthine-containing products, be stopped 24 hours prior to pharmacological stress tests (11770). However, methylxanthines appear more likely to interfere with dipyridamole (Persantine) than adenosine-induced stress testing (11771).

ALCOHOL (Ethanol) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, alcohol might increase the levels and adverse effects of caffeine.  Details Coffee contains caffeine. Concomitant use of alcohol and caffeine can increase caffeine serum concentrations and the risk of caffeine adverse effects. Alcohol reduces caffeine metabolism (6370,24693).

ALENDRONATE (Fosamax) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Coffee reduces alendronate bioavailability.  Details Separate coffee ingestion and alendronate administration by two hours. Coffee reduces alendronate bioavailability by 60% (11735).

ANTICOAGULANT/ANTIPLATELET DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Unlikely •  Level of Evidence = D Theoretically, coffee may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.  Details Coffee contains caffeine. Caffeine is reported to have antiplatelet activity (8028,8029). Theoretically, the caffeine in coffee might increase the risk of bleeding when used concomitantly with these agents. However, this interaction has not been reported in humans. There is some evidence that caffeinated coffee might increase the fibrinolytic activity in blood (8030).

ANTIDIABETES DRUGS Interaction Rating = Minor Be watchful with this combination. Severity = Moderate •  Occurrence = Unlikely •  Level of Evidence = B Theoretically, concomitant use of coffee and antidiabetes drugs might interfere with blood glucose control.  Details Coffee contains caffeine. Reports claim that caffeine might increase or decrease blood sugar levels (6024,8646).

BETA-ADRENERGIC AGONISTS Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = D Theoretically, concomitant use of large amounts of coffee might increase cardiac inotropic effects of beta-agonists.  Details Coffee contains caffeine. Caffeine can increase cardiac inotropic effects of beta-agonists (15).

CIMETIDINE (Tagamet) Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Likely •  Level of Evidence = B Theoretically, cimetidine might increase the effects and adverse effects of caffeine in coffee.  Details Coffee contains caffeine. Cimetidine can reduce caffeine clearance by 31% to 42% (11736,24700).

CLOZAPINE (Clozaril) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = B Theoretically, coffee might increase the levels and adverse effects of clozapine and acutely exacerbate psychotic symptoms.  Details Coffee contains caffeine. Caffeine can increase the effects and toxicity of clozapine. Caffeine doses of 400-1000 mg daily inhibit clozapine metabolism (5051). Clozapine is metabolized by cytochrome P450 1A2 (CYP1A2). Researchers speculate that caffeine might inhibit CYP1A2. However, there is no reliable evidence that caffeine affects CYP1A2. There is also speculation that genetic factors might make some patients be more sensitive to the interaction between clozapine and caffeine (13741).

CONTRACEPTIVE DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = B Theoretically, concomitant use might increase the effects and adverse effects of caffeine found in coffee.  Details Coffee contains caffeine. Oral contraceptive drugs can decrease caffeine clearance by 40% to 65% (2714,11737).

DIPYRIDAMOLE (Persantine) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Theoretically, coffee might decrease the vasodilatory effects of dipyridamole and interfere with its use prior to stress testing.  Details Coffee contains caffeine. Caffeine is a methylxyanthine that may inhibit dipyridamole-induced vasodilation (11770,11772,24974,37985,53795). It is recommended that methylxanthines such as caffeine, as well as methylxanthine-containing products such as coffee, be stopped 24 hours prior to pharmacological stress tests (11770). Methylxanthines appear more likely to interfere with dipyridamole (Persantine) than adenosine-induced stress testing (11771).

DISULFIRAM (Antabuse) Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = B Theoretically, disulfiram might increase the risk of adverse effects from caffeine.  Details Coffee contains caffeine. In human research, disulfiram decreases the clearance and increases the half-life of caffeine (11840).

DIURETIC DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use might increase the risk of hypokalemia.  Details Coffee contains caffeine. Caffeine, especially in excessive amounts, can reduce potassium levels due to stimulation of the sodium-potassium pump (23579,37905,37953,38003,38034). Diuretics can also cause lower potassium levels.

EPHEDRINE Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = D Theoretically, concomitant use might increase the risk of stimulant adverse effects.  Details Coffee contains caffeine. There is evidence that using ephedrine with caffeine might increase the risk of serious life-threatening or debilitating adverse effects such as hypertension, myocardial infarction, stroke, seizures, and death (1275,6486,9740,10307). Tell patients to avoid taking caffeine with ephedrine and other stimulants.

ESTROGENS Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = B Theoretically, estrogens might increase the levels and adverse effects of caffeine.  Details Coffee contains caffeine. Estrogen inhibits caffeine metabolism (2714).

FLUCONAZOLE (Diflucan) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = B Theoretically, fluconazole might increase the levels and adverse effects of caffeine.  Details Coffee contains caffeine. Fluconazole decreases caffeine clearance by approximately 25% (11022,24978).

FLUVOXAMINE (Luvox) Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = B Theoretically, fluvoxamine might increase the levels and adverse effects of caffeine.  Details Coffee contains caffeine. Fluvoxamine reduces caffeine metabolism (6370,38287).

LAMOTRIGINE (Lamictal) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Coffee consumption can decrease the levels and clinical effects of lamotrigine.  Details A pharmacokinetic study in patients taking lamotrigine shows that consumption of coffee, both caffeinated and decaffeinated, can decrease the area under the concentration-time curve (AUC) and the peak plasma level (Cmax) of lamotrigine. Each additional cup of coffee reduced the AUC and Cmax by 4% and 3%, respectively. It is unclear whether this interaction is due to induction of lamotrigine metabolism or inhibition of lamotrigine absorption (107837).

LEVOTHYROXINE (Synthroid, others) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Coffee can reduce the absorption of levothyroxine.  Details In some patients, coffee can reduce levothyroxine absorption, possibly through the formation of non-absorbable complexes. A pharmacokinetic study in these patients found that 25-30 mL of espresso coffee consumed with levothyroxine tablets delayed the time to peak plasma levels by 38-43 minutes, reduced the peak plasma level (Cmax) by 19% to 36%, and reduced the area under the curve (AUC) by 27% to 36%. Coffee consumed one hour after levothyroxine did not affect absorption (16401). It is not known whether this interaction occurs with other types of coffee. Tell patients to avoid drinking coffee at the same time that they take their levothyroxine, and for up to an hour afterwards.

LITHIUM Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = D Theoretically, abrupt coffee withdrawal might increase the levels and adverse effects of lithium.  Details Coffee contains caffeine. Abrupt caffeine withdrawal can increase serum lithium levels (609). Two cases of lithium tremor that worsened with abrupt coffee withdrawal have been reported (609,610). There is also one case of a 2.8-fold increase in blood lithium levels after a patient taking lithium reduced his coffee consumption from 13-20 cups daily to 10 cups daily (97369).

MEXILETINE (Mexitil) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = B Theoretically, mexiletine might increase the levels and adverse effects of caffeine.  Details Coffee contains caffeine. Mexiletine can decrease caffeine elimination by 50% (1260,11741,24981).

MONOAMINE OXIDASE INHIBITORS (MAOIs) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use might increase the risk of a hypertensive crisis.  Details Coffee contains caffeine. Caffeine has been shown to inhibit monoamine oxidase (MAO) A and B in laboratory studies (37724,37877,37912,38108). Concomitant intake of large amounts of caffeine with MAOIs might precipitate a hypertensive crisis (15). In a case report, a patient that consumed 10-12 cups of caffeinated coffee and took the MAOI tranylcypromine presented with severe hypertension (91086). Hypertension was resolved after the patient switched to drinking decaffeinated coffee.

NICOTINE Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Theoretically, concomitant use might increase the risk of hypertension.  Details Coffee contains caffeine. Concomitant use of caffeine and nicotine has been shown to have additive cardiovascular effects, including increased heart rate and blood pressure. Blood pressure was increased by 10.8/12.4 mmHg when the agents were used concomitantly (36549).

PENTOBARBITAL (Nembutal) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, coffee might reduce the effects of pentobarbital.  Details Coffee contains caffeine. Theoretically, caffeine might negate the hypnotic effects of pentobarbital (13742).

PHENOTHIAZINES Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, phenothiazines might increase the levels and adverse effects of caffeine. Also, coffee may bind to phenothiazines and reduce their absorption.  Details Coffee contains caffeine. Phenothiazines can reduce the metabolism of caffeine by inhibiting cytochrome P450 1A2 (CYP1A2) (23573,23574). Additionally, the tannins in coffee may bind to phenothiazines in the gastrointestinal tract and reduce their absorption (626,627).

PHENYLPROPANOLAMINE Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Theoretically, phenylpropanolamine might increase the risk of hypertension, as well as the levels and adverse effects of caffeine.  Details Coffee contains caffeine. Concomitant use of phenylpropanolamine and caffeine might cause an additive increase in blood pressure (11738). Phenylpropanolamine also seems to increase caffeine serum levels (13743).

PIOGLITAZONE (Actos) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, coffee might increase the levels and clinical effects of pioglitazone.  Details Coffee contains caffeine. Animal research suggests that caffeine can modestly increase the maximum concentration, area under the curve, and half-life of pioglitazone, and also reduce its clearance. This increased the antidiabetic effects of pioglitazone (108812). However, the exact mechanism of this interaction is unclear.

QUINOLONE ANTIBIOTICS Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = B Theoretically, quinolone antibiotics might increase the levels and adverse effects of caffeine.  Details Coffee contains caffeine. Concomitant use of caffeine and quinolones can decrease caffeine clearance and increase effects and risk of adverse effects (606,607,608,23555,24695,24696,24697).

RILUZOLE (Rilutek) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use might increase the levels and adverse effects of both caffeine and riluzole.  Details Coffee contains caffeine. Caffeine and riluzole are both metabolized by cytochrome P450 1A2 (CYP1A2), and concomitant use might reduce metabolism of one or both agents (11739).

STIMULANT DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = C Theoretically, concomitant use might increase stimulant adverse effects.  Details Coffee contains caffeine. Due to the central nervous system (CNS) stimulant effects of caffeine, concomitant use with stimulant drugs can increase the risk of adverse effects (11832).

TERBINAFINE (Lamisil) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = B Theoretically, terbinafine might increase the levels and adverse effects of caffeine.  Details Coffee contains caffeine. Terbinafine decreases the clearance of intravenous caffeine by 19% (11740).

THEOPHYLLINE Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = B Theoretically, coffee might increase the levels and adverse effects of theophylline.  Details Coffee contains caffeine, which can increase theophylline levels (11741,11862,24984).

TRICYCLIC ANTIDEPRESSANTS (TCAs) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, TCAs might bind with coffee constituents when taken at the same time.  Details In vitro research suggests that the tannins in coffee might cause precipitation of TCAs (626,627). However, this effect has not been reported in humans.

VERAPAMIL (Calan, others) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use might increase the levels and adverse effects of caffeine.  Details Coffee contains caffeine. Verapamil increases plasma caffeine concentrations by 25% (11741).

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General ...Orally, caffeinated or decaffeinated coffee is well tolerated in moderate amounts.
Most Common Adverse Effects:
Orally: Drinking coffee containing caffeine can cause agitation, anxiety, chest pain, diuresis, gastric distress, headache, insomnia, nervousness, premature heart rate, ringing in the ears, and vomiting. These effects are more likely with increasing intake of caffeine and in certain populations (e.g., children, elderly). With chronic caffeine use, especially in large amounts, habituation, tolerance, and psychological dependence can occur.
Abrupt discontinuation of caffeine may result in physical withdrawal symptoms, including anxiety, decreased physical energy, depressed mood, difficulty concentrating, drowsiness, fatigue, headache, irritability, reduced alertness, and rhinorrhea.
Rectally: Coffee enemas have been linked to proctocolitis, severe electrolyte abnormalities, and septicemia leading to death.

Cardiovascular ...Orally, coffee containing caffeine can cause chest pain and premature heartbeat (8042,111045). These effects are more likely with increasing intake of caffeine and in certain populations (e.g., children, elderly) (8042). Excessive doses of caffeine can cause massive catecholamine release and subsequent sinus tachycardia (11832,11838,13734,13735).
Although acute administration of caffeine can cause increased blood pressure, regular consumption does not seem to increase either blood pressure or pulse, even in hypertensive patients (1451,1452,2722,13739,105312). Drinking one or more cups of caffeinated coffee daily also doesn't seem to increase the risk of developing hypertension in habitual coffee drinkers (8033,13739,111037).
Epidemiological research has found that regular caffeine intake of up to 400 mg daily, or approximately 4 cups of caffeinated coffee, is not associated with an increased incidence of atrial fibrillation (38018,38076,91028,91034,97451,97453,105310), atherosclerosis (38033), cardiac ectopy (91127), stroke (37804), ventricular arrhythmia (95948,97453,105310), or cardiovascular disease (CVD) in general (37805,98806,104882). However, some observational research suggests that drinking at least 1 cup of coffee per week is associated with a 40% increased risk of atrial fibrillation, with the highest incidence of atrial fibrillation occurring in adults consuming at least 6 cups daily (111042). Also, one large, observational study found a J-shaped association between regular coffee consumption and the risk of developing acute coronary syndromes. Moderate consumption of less than 300 mL daily (about 1.3 cups) was associated with a lower risk of developing acute coronary syndromes, whereas regular consumption of 300 mL daily or more was associated with an increased risk (11318). In contrast, other observational research in people without a history of CVD has found that drinking more than 6 cups of coffee daily does not appear to be associated with an increased risk of developing coronary heart disease (14343). Also, in people with a history of CVD, population research has found that coffee consumption is associated with a reduction in CVD-related mortality (97373,97374,103997,103998,104594,104595,104882,105308,105311,105313,105314). However, in current smokers with a history of acute coronary syndrome, consuming more than 3 cups of coffee daily is associated with more than a two-fold increased risk of overall mortality (105313). Also, population research in patients with severe hypertension, but not mild hypertension, suggests that drinking at least two cups of coffee daily is associated with a 2-fold increase in CVD mortality compared with non-coffee drinkers (111027).
Caffeine intake may pose a greater cardiovascular risk to subjects who are not regular caffeine users. Population research suggests that drinking caffeinated coffee might trigger a myocardial infarction (MI) in some people. People who drink one or fewer cups of coffee daily and are sedentary and have multiple risk factors for heart disease have a significantly increased risk of MI within an hour after drinking coffee. However, this risk appears diminished in people who routinely consume greater amounts of coffee on a daily basis (14497). In another population study, caffeinated coffee consumption was associated with an increased risk of ischemic stroke in subjects who didn't regularly drink coffee (38102).
Boiled coffee that is prepared without a filter appears to increase serum cholesterol and triglyceride levels (1353,4200,8036,8539). Drinking one liter of strong, unfiltered coffee daily for two weeks can raise serum cholesterol by 10% and serum triglycerides by 36% (1353). Tell patients to use coffee filters since these effects do not seem to occur with filtered coffee (4200,8036,8539).
Coffee can adversely affect homocysteine levels. Higher homocysteine levels have been associated with CVD. One liter of unfiltered strong coffee daily for two weeks can increase plasma homocysteine levels by 10% (1353). The same amount of filtered strong coffee appears to raise plasma homocysteine levels by 20%, although there have been no head-to-head comparisons of filtered versus unfiltered coffee (3344).

Dermatologic ...Some researchers suggest symptoms such as flushed face occur during caffeine withdrawal. However, withdrawal symptoms may be due to nonpharmacological factors related to knowledge and expectation of effects. Clinically significant symptoms caused by caffeine withdrawal may be uncommon (2723,11839).

Endocrine ...Orally, excessive doses of caffeine can cause massive catecholamine release and subsequent metabolic acidosis, hyperglycemia, and ketosis (13734). Other symptoms include hypokalemia and respiratory alkalosis (11832,11838,13735).
Some evidence shows that caffeine, a constituent of coffee, is associated with fibrocystic breast disease, breast cancer, and endometriosis in females; however, this is controversial since findings are conflicting (8043). Restricting caffeine intake in patients with fibrocystic breast conditions doesn't seem to affect breast nodularity, swelling, or pain (8996). Population research suggests that exposure to caffeine is not associated with an increased risk of endometriosis (91035).
A population analysis of the Women's Health Initiative observational study has found no association between consumption of caffeine-containing beverages, such as coffee, and the incidence of invasive breast cancer in models adjusted for demographic, lifestyle, and reproductive factors (108806). Also, a dose-response analysis of 2 low-quality observational studies has found that high consumption of caffeine is not associated with an increased risk of breast cancer (108807).

Gastrointestinal ...Orally, coffee containing caffeine can cause gastric distress and vomiting. These effects are more likely with increasing intake of caffeine and in certain populations (e.g., children, elderly) (8042,13734). There is also some evidence that consumption of three or more cups of caffeinated coffee might increase the risk of Helicobacter pylori infection (8034).
Caffeine withdrawal symptoms such as nausea and vomiting have been described. However, these symptoms may be due to nonpharmacological factors related to knowledge and expectation of effects. Clinically significant symptoms caused by caffeine withdrawal may be uncommon (2723,11839).
Rectally, at least 5 cases of proctocolitis related to the use of coffee enemas have been reported (96868,103273).

Genitourinary ...The caffeine found in coffee is a known diuretic and may increase voiding, give a sense of urgency, and irritate the bladder (37874,37961,104580). In males with lower urinary tract symptoms, caffeine intake increased the risk of interstitial cystitis/painful bladder syndrome (38115). Excessive caffeine consumption may worsen premenstrual syndrome. Consumption of up to 10 cups of caffeinated drinks daily has been associated with increased severity of premenstrual syndrome (38177).

Hematologic ...There is evidence that coffee containing caffeine shortens whole blood fibrinolysis time (8030).
Rectally, coffee enemas have been linked to severe electrolyte abnormalities leading to death (3026,3347,3349,6652)

Hepatic ...Boiled coffee that is prepared without a filter appears to increase liver aminotransferase enzymes. Tell patients to use coffee filters since these effects do not seem to occur with filtered coffee (8539).

Immunologic ...Caffeine can cause anaphylaxis in sensitive individuals, although true IgE-mediated caffeine allergy seems to be relatively rare (11315).
Rectally, coffee enemas have been linked to septicemia leading to death (3026,3347,3349,6652).

Musculoskeletal ...Orally, there is preliminary evidence that use of greater than four cups of coffee daily can increase the risk of rheumatoid factor positive rheumatoid arthritis, but this association has not been confirmed (6482).
Epidemiological evidence regarding the relationship between caffeine use and the risk for osteoporosis is contradictory. Caffeine can increase urinary excretion of calcium (2669,10202,11317). Females identified with a genetic variant of the vitamin D receptor appear to be at an increased risk for the detrimental effect of caffeine on bone mass (2669). However, moderate caffeine intake of less than 400 mg daily does not seem to significantly increase osteoporosis risk in most postmenopausal adults with normal calcium intake (2669,6025,10202,11317,98806).
Caffeine withdrawal symptoms, such as muscle tension and muscle pains, have been described. However, these symptoms may be due to nonpharmacological factors related to knowledge and expectation of effects. Clinically significant symptoms caused by caffeine withdrawal may be uncommon (2723,11839).

Neurologic/CNS ...Orally, coffee containing caffeine can cause agitation, headache, insomnia, and nervousness, . These effects are more likely with increasing intake of caffeine and in certain populations (e.g., children, elderly) (8042,11832,11838,13734,13735).
Combining ephedra with coffee can increase the risk of adverse effects, due to the caffeine contained in coffee. Jitteriness, seizures, and temporary loss of consciousness have been associated with the combined use of ephedra and caffeine (2729).
Some researchers suggest that symptoms such as headache; tiredness and fatigue; decreased energy, alertness, and attentiveness; drowsiness; decreased contentedness; difficulty concentrating; irritability; and lack of clear-headedness are typical of caffeine withdrawal (13738). Withdrawal symptoms such as delirium, nervousness, and restlessness have also been described. However, these symptoms may be due to nonpharmacological factors related to knowledge and expectation of effects. Clinically significant symptoms caused by caffeine withdrawal may be uncommon (2723,11839).

Ocular/Otic ...Orally, coffee containing caffeine can cause ringing in the ears. This is more likely with increasing intake of caffeine and in certain populations (e.g., children, elderly) (8042,13734). Coffee containing caffeine also increases intraocular pressure, starting about 30 minutes after consumption and persisting for at least 90 minutes. Decaffeinated coffee does not appear to affect intraocular pressure (8540).

Oncologic ...The association between consumption of coffee and pancreatic cancer is controversial. Coffee may increase the incidence of some types of pancreatic cancers, but it may decrease other types (8535,8536,8537). Some studies do not support this association, especially in patients that have never smoked (8038,8040,93878,103999). Patients who are at risk of pancreatic cancer (pancreatitis) should limit their consumption of coffee.
People who consume 2-4 or more cups of caffeinated coffee dail might have a significantly increased risk of developing lung cancer (13191,90177). But drinking decaffeinated coffee seems to be associated with a decreased risk of lung cancer (13191).
Coffee consumption has also been associated at various times with an increased risk of breast cancer, bladder cancer, colon cancer, and other types of cancers, but there's no good evidence that coffee consumption increases cancer risk (8039,8040,8041). Most human studies that have examined caffeine or coffee intake have found that they do not play a role in the development of various cancers, including breast or most gastric cancers (91054,91076,98806). However, drinking caffeinated coffee might increase the risk of gastric cardia cancer (91076).

Psychiatric ...Orally, coffee containing caffeine can cause anxiety. This is more likely with increasing intake of caffeine and in certain populations (e.g., children, elderly) (8042,13734). With chronic use, especially in large amounts, habituation, tolerance, and psychological dependence can occur (3719). Other researchers suggest symptoms such as depressed mood are typical of caffeine withdrawal (13738). However, withdrawal symptoms may be due to nonpharmacological factors related to knowledge and expectation of effects. Clinically significant symptoms caused by caffeine withdrawal may be uncommon (2723,11839).

Pulmonary/Respiratory ...Caffeine withdrawal symptoms such as rhinorrhea have been described. However, these symptoms may be due to nonpharmacological factors related to knowledge and expectation of effects. Clinically significant symptoms caused by caffeine withdrawal may be uncommon (2723,11839).

Renal ...Orally, coffee containing caffeine can cause diuresis. This is more likely with increasing intake of caffeine and in certain populations (e.g., children, elderly) (8042,13734).

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