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Caffeine

Caffeine  

Natural Standard Monograph, Copyright © 2013 (www.naturalstandard.com). Commercial distribution prohibited. This monograph is intended for informational purposes only, and should not be interpreted as specific medical advice. You should consult with a qualified health care professional before making decisions about therapies and/or health conditions.

Related Terms

  • 1,3,7-Trimethylxanthine, 1,3-dimethylxanthine, 1,7-dimethylxanthine, 3,7-dimethylxanthine, 7-methyltheophylline, acetaminophen-caffeine, adenosine antagonist, anhydrous caffeine, aspirin-acetaminophen-caffeine, aspirin-salicylamide-caffeine, black tea, bronchodilator, butalbital-aspirin-caffeine, C8H10N4O2, cacao beans, cafeína (Spanish), caffea, caffedrine, caffeina citrata, caffeina citrata effervescens, caffeine anhydrous, caffeine choline, caffeine citrate, caffeine citrated intravenous, caffeine citrated oral, caffeine-sodium benzoate, chocolate, citrated caffeine, cocoa, Coffea, coffee, coffee beans, diuretic, effervescent citrated caffeine, energy drink, ergogenic aid, ergotamine-caffeine, espresso, green tea, guarana, guarana berries, kola nut, methylxanthine, orphenadrine-aspirin-caffeine, paraxanthine, psychoactive drug, soft drinks, stimulant, tea, theobromine, theophylline, trimethylxanthine, xanthine, yerba mate.
  • Select products and brand names: Cafcit®, Enerjets®, NoDoz®, NoDoz® Maximum Strength, Stay Awake®, Vivarin®.
  • Select combination products: Actamin® Super (acetaminophen and caffeine); Anacin®, Anacin® Advanced Headache Formula, Excedrin®, Goody's® Extra Strength, Goody's® Cool Orange, Vanquish® (acetaminophen, aspirin, and caffeine); Bayer® Headache Relief (aspirin and caffeine); Cafergot®, Cafetrate®, Cafertrine®, Ercaf®, Ergo-Caff®, Gotamine®, Migergot®, Wigraine® (ergotamine and caffeine); Fiorinal® (aspirin, butalbital, and caffeine); Fiorinal® with Codeine No. 3 (aspirin, butalbital, caffeine, and codeine), Medi-First® Pain Relief, Medi-First® Pain Zapper (aspirin, acetaminophen, salicylamide, caffeine); Midol® Complete (acetaminophen, pyrilamine maleate, and caffeine); Norgesic®, Norgesic® forte (orphenadrine citrate, aspirin, caffeine); Revive® energy mints (caffeine, guarana, ginseng, green tea, açaí berry, mangosteen, and goji berry).
  • Note: Caffeine is found in many foods and drinks, including black tea, green tea, and yerba mate. Separate summaries are available on these topics. Products containing caffeine are not addressed in detail in this summary.

Background

  • Caffeine is a naturally occurring compound found in the leaves, seeds, or fruits of more than 60 plants, including coffee (Coffea arabica) beans, cacao (Theobroma cacao) beans, kola (Cola acuminata) nuts, guarana (Paullinia cupana) berries, and tea (Camellia sinensis) leaves. Caffeine is consumed regularly in the United States and throughout the world. It is found in many beverages, including coffee, chocolate, some energy drinks, and tea. More than seven kilograms of caffeine per person are consumed in the United States per year.
  • Caffeine was first discovered in 1819 by the German chemist Friedlieb Ferdinand Runge. He coined the term Kaffein, a chemical compound in coffee, which became caffeine in English.
  • Humans have consumed caffeine since the Stone Age. It was during this time that people discovered that chewing the seeds, bark, and leaves of certain plants reduced fatigue, increased awareness, and improved mood. The first known pot of tea dates back to 2737 BC, when the Chinese emperor Shen Nung boiled drinking water when the leaves of a nearby bush fell into the pot. Coffee was first noted in Africa around AD 575, when beans were used as money and eaten as food. Arabians of the 11th Century were known to have coffee beverages. In 1519, Spanish conquerors were treated to a chocolate drink by the Aztec emperor Montezuma. The world's first caffeinated soft drinks were created in the 1880s.
  • In people, caffeine may be useful to stimulate the heart and increase urine flow. Caffeine has been shown to affect mood, endurance, the brain, and blood vessels, as well as activity in both the stomach and colon. Caffeine has also been marketed as a weight loss tool and is often included in various weight loss supplements.

Evidence

 

Uses based on scientific evidence 

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare professional.

Grade* 

Apnea 

In preterm infants, apnea is defined as the stoppage of breathing for 20 seconds or longer. It is one of the most common breathing disorders in the neonatal intensive care unit. Caffeine is a breathing stimulant commonly used to treat apnea. Scientific evidence supports the use of caffeine in the treatment and prevention of apnea in premature infants.

A 

Cognitive performance 

Caffeine has a long history of use for enhancing mood and cognitive (mental) function. Caffeine may be useful when consumed prior to a cognition-related task. It also appears to heighten working memory and improve reaction time, but it has less effect on long-term memory.

A 

Exercise performance 

Caffeine is a known stimulant that may enhance endurance and performance when used before exercise, particularly in low-to-moderate doses. Caffeine in dry form appears to be more beneficial than coffee or tea. However, its use as a performance-enhancing agent remains controversial. Caffeine should be used with caution, as it may increase blood pressure, heart rate, and urine flow.

A 

Respiratory disorders 

Caffeine is a weak type of methylxanthine. Methylxanthines are a class of drugs that open the airways and promote airflow. As such, these types of agents are used to help manage conditions whereby airflow is restricted, such as asthma and chronic obstructive pulmonary disease (COPD). Research suggests that caffeine reduces asthma symptoms, including exercise-induced airway constriction. Caffeine has also been suggested to reduce airway muscle fatigue.

A 

Headaches 

Evidence suggests that caffeine may have pain-relieving effects. In particular, caffeine has shown useful effects for relieving hypnic migraines (headaches that occur during sleep) and headaches that occur after punctures to the lower back. Although promising, more well-designed trials are needed in this area.

B 

Attention-deficit hyperactivity disorder (ADHD) 

There is conflicting evidence supporting the use of caffeine in the treatment of ADHD in children. Additional research is needed in this area.

C 

Diabetes 

Caffeine and coffee may lower the risk of type 2 diabetes and prevent exercise-induced low blood sugar in type 1 diabetes. However, the research in this area is not consistent, as caffeine has been previously associated with impaired glucose tolerance and insulin sensitivity. Additional research is needed in this area.

C 

Intermittent claudication 

Limited evidence suggests that caffeine may have positive effects on physical capacity in patients with intermittent claudication (muscle pain in the limbs). Additional research is needed to confirm early results.

C 

Kwashiorkor (children) 

Preliminary evidence suggests that caffeine improves alertness and appetite during the nutritional rehabilitation of children and may therefore have positive effects as an added therapy in the treatment of kwashiorkor (a form of childhood malnutrition). More high-quality research is needed in this area before any firm conclusions can be made.

C 

Liver disease 

Preliminary research suggests that caffeine may have beneficial effects against excess tissue buildup in the liver and that it may be associated with a lower risk of liver disease. However, well-designed trials are needed in this area before any firm conclusions can be drawn.

C 

Mood 

Caffeine is well known for its mood-changing effects. However, current evidence on the relationship between caffeine and depression risk is conflicting, with some studies showing beneficial effects and others showing a lack of effect. Further high-quality research is needed in this area before any firm conclusions can be made.

C 

Obsessive compulsive disorder (OCD) 

Limited evidence suggests that the effects of caffeine are similar to those of d-amphetamine. D-amphetamine is a drug known to promote alertness and focus. Although this is promising, additional research is needed to clarify these early findings.

C 

Pain 

Evidence suggests that caffeine may have pain-relieving effects. According to early research, caffeine has shown beneficial effects against headache- and muscle ache-related pain. More well-designed trials are needed in this area before any firm conclusions can be drawn.

C 

Parkinson's disease 

Limited evidence suggests that increased coffee and caffeine consumption may be related to decreased risk of Parkinson's disease. Further high-quality research is needed in this area before any firm conclusions can be drawn.

C 

Skin conditions (wrinkles, stretch marks, cellulite) 

The skin application of caffeine for the treatment of wrinkles, stretch marks, and cellulite is growing in popularity. However, the effect of caffeine alone cannot be determined, as most products contain a mixture of agents. Further research assessing the use of caffeine alone is needed in this area.

C 

Stroke 

Both theophylline and caffeine are types of methylxanthines. Methylxanthines are a class of drugs that narrow blood vessels in the brain. Due to this effect, early research suggests that theophylline may be useful in stroke patients. However, the effect of caffeine in this area is unclear. More high-quality trials are needed before a conclusion can be drawn.

C 

Weight loss 

Early research suggests that caffeine may be useful for weight loss, particularly when combined with other agents, such as green tea. Although caffeine has shown some positive effects on urine flow, exercise performance, heat production, and feelings of fullness, conflicting results have been seen with respect to its effects on blood sugar levels. Further studies are needed in this area before any firm conclusions can be drawn.

C 

 

*Key to grades: 

A: Strong scientific evidence for this use;
B: Good scientific evidence for this use;
C: Unclear scientific evidence for this use;
D: Fair scientific evidence against this use (it may not work);
F: Strong scientific evidence against this use (it likely does not work).

For full grading rationale, click here.

Uses based on tradition or theory 

The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified health care professional

Aging, alcohol abuse, allergies, amyotrophic lateral sclerosis (ALS), anti-inflammatory, antioxidant, bladder disorders, bowel health, brain tumors, cancer, cataracts, cavities, cerebral insufficiency (decreased blood flow to the brain), cocaine dependence, diuretic (increases urine flow), eczema (inflamed and irritated skin), epilepsy (seizure), gallstones, gout, Huntington's disease, immune system regulation, insecticide, ischemic heart disease (decreased blood flow to the heart), kidney disorders, low blood pressure (upon standing), malaria, motion sickness, multiple sclerosis, nausea and vomiting during pregnancy, neurological disorders (Joubert syndrome), photoprotection (protection from UV radiation), sepsis (bacterial infection of the blood or tissues), schizophrenia, sinusitis (nasal sinus inflammation), snoring, traumatic brain injury, UV-induced erythema prevention/sunburn, vasorelaxant (relaxes blood vessel walls), viral infections, vitiligo (white patches on the skin), work shift sleep disorder.


Safety

The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare professional before starting a new therapy. Consult a healthcare professional immediately if you experience side effects.

Allergies

  • Avoid with known allergy or hypersensitivity to caffeine. A temporary rise in heart rate and blood pressure has been reported in those who are hypersensitive to caffeine. Urticaria (skin rash and hives) after consuming coffee has also been reported. Historically, inhalation of coffee bean dust may produce "coffee worker's lung," a type of allergic lung inflammation.

Side Effects and Warnings

  • Individuals who metabolize caffeine differently may be at increased risk for side effects.
  • Stomach irritation or upset, nausea, diarrhea, abdominal pain, and loss of bowel control may occur with caffeine intake. Caffeine may increase levels of stress hormones (including cortisol, epinephrine, and norepinephrine) and stimulate ulcer formation. Coffee may increase stomach acid production and increase the incidence of acid reflux heartburn, gastroesophageal reflux disease (GERD), regurgitation, and difficult or painful swallowing. Coffee may also speed up the process of stomach emptying, possibly leading to injury of the intestinal tissue.
  • Other possible side effects of caffeine include agitation, airway inflammation, anxiety, daytime sleepiness, dehydration, delayed conception, depleted carbon monoxide levels in the blood, depression, difficulty thinking clearly, display of anger, drowsiness, fatigue, headaches, hyperactivity, impaired alertness and attention, impaired memory retention, increased chronic back pain, increased frequency and severity of premenstrual syndrome (PMS), increased occurrence of gallstone polyps, increased risk of Parkinson's disease and multiple sclerosis, increased risky behavior (including binge drinking, drinking and driving, sexual activity, and suicidal acts), irritability, jitteriness, lack of energy, loss of B vitamins, mild delirium, nervousness, overactive reflexes, panic attacks, poor feeding, reduced blood potassium levels, reduced semen quality, restlessness, shortened menstrual cycle, sleep disturbances, suppressed immune function, sweating, teeth grinding, wakefulness, and worsened liver damage,
  • Caffeine is a known stimulant agent and may increase heart rate or cause irregular heartbeats. Caffeine may also be associated with adverse effects on blood vessel function and increased risk of ischemic stroke (blocked blood flow to the brain). Use cautiously in people with a known history of abnormal heart rhythms.
  • Caffeine is a known diuretic (an agent that increases urine production). Use cautiously in people with an overactive bladder or other urologic disorders and in those taking other diuretic agents. Caffeine may increase voiding, give a sense of urgency, and irritate the bladder.
  • Although it has not been well studied in humans, caffeine may increase the risk of bleeding. Caution is advised in people with bleeding disorders and in those taking drugs that may increase the risk of bleeding (including warfarin). Dosing adjustments may be necessary.
  • Caffeine may increase blood sugar levels. Caution is advised in people with diabetes or hypoglycemia and in those taking drugs, herbs, or supplements that affect blood sugar. Blood glucose levels may need to be monitored by a qualified healthcare professional, including a pharmacist. Medication adjustments may be necessary.
  • Caffeine may increase blood pressure. Caution is advised in people with high blood pressure and in those taking drugs, herbs, or supplements that lower blood pressure (including phenylpropanolamine).
  • Caffeine may increase blood lipids. Caution is advised in people with elevated blood lipids and in those taking drugs, herbs, or supplements that alter lipid levels.
  • Caffeine may be associated with seizures. Caution is advised in people with seizure disorders and those taking any drugs to prevent or treat seizures, or when combined with any agents that lower the seizure threshold (including carbamazepine, phenobarbital, phenytoin, valproate, and ethosuximide).
  • Use cautiously in people with heightened sensitivity to caffeine.
  • Use cautiously in people with movement disorders or those using drugs that may cause such disorders (e.g., neuroleptics). Caffeine may cause muscle tremors, impair muscle coordination, or provoke disorders that cause uncontrolled movement (e.g., familial paroxysmal nonkinesigenic dyskinesia).
  • Use cautiously in people with osteoporosis or those at risk for osteoporosis, as caffeine may decrease bone mineral density, promote bone loss, and increase fracture risk.
  • Use cautiously in people with sleep disorders like insomnia and in those taking other central nervous system (CNS) stimulants, as caffeine may increase these effects and cause insomnia.
  • Use cautiously in people with glaucoma, as caffeine may increase eye pressure.
  • Use cautiously in people at risk for kidney stones, as caffeine has been associated with higher urinary calcium, therefore posing an increased risk.
  • Use cautiously in people with eating disorders, as a high incidence of caffeine consumption may increase the risk of anxiety and mood disorders.
  • Use cautiously in people who have a weakened immune system and in those using immune system-lowering agents, as caffeine may alter immune function, particularly after exercise.
  • Use cautiously in people with breast disease, stomach disorders, growth hormone deficiency, or high-grade inflammation; those at risk for kidney or breast cancer; and those who do not consume caffeine regularly (including athletes), due to and increased risk for side effects.
  • Use cautiously in firefighters wearing protective clothing, as they may be more susceptible to heat-related fatigue and injury.
  • Use cautiously over prolonged periods of time. Chronic caffeine use may result in increased tolerance and dependence.
  • Use cautiously in combination with adenosine, agents that affect dopamine, agents that affect the liver's cytochrome P enzyme system (e.g., amitriptyline, ciprofloxacin, clozapine, coconut products, danshen (Salvia miltiorrhiza), disulfiram, echinacea (Echinacea spp.), enoxacin, ethinyl estradiol, flutamide, fluvoxamine, furafylline, genistein, grapefruit juice, imipramine, kudzu (Pueraria lobata), melatonin, methoxsalen, methylxanthines, mexiletine, omeprazole, phenothiazines, and riluzole), agents that depress the central nervous system (e.g., diazepam, midazolam, triazolam, zolpidem, and zopiclone), agents that dilate or constrict blood vessels, agents that mimic the effects of the sympathetic nervous system, antidepressants (e.g., monoamine oxidase inhibitors; MAOIs), antipyrine, calcium, corticosteroids, creatine, fluconazole, geranium (Geranium spp.), iron, lithium, magnesium, and potassium.
  • Use cautiously in children and the elderly.
  • Use cautiously for periods greater than four weeks in preterm infants, due to the risk of reduced weight gain and increased oxygen consumption.
  • Caffeine may pass through breast milk. Use cautiously in amounts greater than three cups of coffee daily in breastfeeding women.
  • Avoid amounts greater than 200 milligrams daily in pregnant women.
  • Avoid in people with rosacea (enlarged facial blood vessels).
  • Avoid in people with Marfan syndrome (a connective tissue disorder), as agents like caffeine that stimulate the cardiovascular system should not be used with this disorder.
  • Avoid in people with autosomal recessive polycystic kidney disease (a type of genetic kidney disease), as caffeine may promote kidney cyst growth.
  • Avoid use before adenosine, cardiac, or dipyridamole stress testing, due to potential interference with results.
  • Avoid use in combination with agents that stimulate the central nervous system, alcohol, and herbs that contain caffeine.
  • Avoid in those with known allergy or hypersensitivity to caffeine. Elevated heart rate, increased blood pressure, urticaria (skin rash and hives), and allergic lung inflammation have been reported following caffeine and coffee exposure.

Pregnancy and Breastfeeding

  • Although it has not been well studied in humans, the consumption of one cup of coffee daily may be associated with a lowered chance of getting pregnant.
  • Possible side effects of caffeine use during pregnancy include increased risk of early delivery, miscarriage, neural tube defects (especially spinal cord malformations such as spina bifida), and stillbirth. Possible side effects on the baby include impaired skeletal growth, decreased length, and reduced birthweight,
  • Use cautiously during pregnancy, as caffeine may pass through the placenta and reach the baby. Also, the clearance of caffeine from the body may be extended during this time. Avoid use of more than 200 milligrams daily in pregnant women.
  • Use cautiously in breastfeeding women, as caffeine may pass through breast milk and reach the baby. This is particularly important for premature babies, as their ability to break down caffeine may not be fully developed yet. Avoid more than three cups of coffee daily in breastfeeding women.
  • In babies, possible side effects of caffeine use during breastfeeding include irritability, jitteriness, restlessness, stimulatory effects, wakefulness, poor feeding, and mild iron deficiency due to decreased iron in breast milk.

Interactions

Most herbs and supplements have not been thoroughly tested for interactions with other herbs, supplements, drugs, or foods. The interactions listed below are based on reports in scientific publications, laboratory experiments, or traditional use. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare professional before starting a new therapy.

Interactions with Drugs

  • Caffeine may increase the risk of bleeding when taken with drugs that increase the risk of bleeding. Some examples include aspirin, anticoagulants (blood thinners) such as warfarin (Coumadin®) or heparin, antiplatelet drugs such as clopidogrel (Plavix®), and nonsteroidal anti-inflammatory drugs such as ibuprofen (Motrin®, Advil®) or naproxen (Naprosyn®, Aleve®).
  • Caffeine may raise blood sugar levels. Caution is advised when using medications that may affect blood sugar (such as metformin). Patients taking drugs for diabetes by mouth or insulin should be monitored closely by a qualified healthcare professional, including a pharmacist. Medication adjustments may be necessary.
  • Caffeine may increase blood pressure. Caution is advised in patients taking drugs, herbs, or supplements that may affect blood pressure.
  • Caffeine may interfere with the way the body processes certain drugs using the liver's cytochrome P450 enzyme system (e.g., ticlopidine). As a result, the levels of these drugs may be altered in the blood and may change the intended effects. Patients taking any medication should check the package insert and speak with a qualified healthcare professional, including a pharmacist, about possible interactions.
  • Caffeine may also interact with adenosine, agents that affect dopamine, agents that increase urine production, agents that mimic sympathetic nervous system activity (e.g., phenylpropanolamine (PPA)), agents that narrow and widen blood vessels (e.g., nifedipine), agents that regulate heart rate, agents that widen airways, alcohol, Alzheimer's agents, amphetamine, antiandrogens (e.g., flutamide), antiasthma drugs (e.g., furafylline), antibiotics, anticancer drugs (e.g., cisplatin, cyclophosphamide, doxorubicin, ifosfamide, mitomycin C, pazopanib, and temozolomide), antidepressants, antifungals (e.g., terfenadine), antiglaucoma agents, antiobesity agents (e.g., ephedrine), antiparkinsonians (e.g., levodopa), antipsychotics (e.g., phenothiazines), antipyrine, antiseizure drugs (e.g., carbamazepine, ethosuximide, felbamate, phenobarbital, phenytoin, terfenadine, and valproic acid), antiulcer agents (e.g., cimetidine), barbiturates (e.g., pentobarbital), benzodiazepines (e.g., lorazepam), beta-agonists, beta-blockers (e.g., propranolol), calcium salts, celecoxib, central nervous system (CNS) depressants (e.g., diazepam, midazolam, triazolam, zolpidem, zopiclone), clozapine, CNS stimulants, cocaine, contraceptives, corticosteroids, darifenacin, decongestants, dipyridamole, disulfiram, drugs that may lower the seizure threshold, ergot derivatives, estrogens, flubendiamide, fluconazole, fluvoxamine, growth hormone, H2 blockers, hydrocortisone, immune system-lowering agents, inotropes, iron salts, lipid-lowering drugs, lithium, magnesium supplements, methoxsalen, methylenedioxymethamphetamine (MDMA, or "Ecstasy"), methylphenidate, methylxanthines, mexiletine, morphine, nicotine, oseltamivir (Tamiflu®), pain relievers (e.g., acetaminophen, aspirin, ibuprofen, and tramadol), perazine, potassium salts, potassium-depleting drugs, proton pump inhibitors (PPIs) (e.g., omeprazole), quinolones (e.g., ciprofloxacin), riluzole, rosuvastatin, sedatives, terbinafine, and theophylline.

Interactions with Herbs and Dietary Supplements

  • Caffeine may increase the risk of bleeding when taken with herbs and supplements that are believed to increase the risk of bleeding. Multiple cases of bleeding have been reported with the use of Ginkgo biloba, and fewer cases with garlic and saw palmetto. Numerous other agents may theoretically increase the risk of bleeding, although this has not been proven in most cases.
  • Caffeine may raise blood sugar levels. Caution is advised when using herbs or supplements that may also affect blood sugar. Blood glucose levels may require monitoring, and doses may need adjustment.
  • Caffeine may increase blood pressure. Caution is advised in patients taking drugs, herbs, or supplements that may affect blood pressure.
  • Caffeine may interfere with the way the body processes certain herbs or supplements using the liver's cytochrome P450 enzyme system. As a result, the levels of other herbs or supplements may be altered in the blood. It may also alter the effects that other herbs or supplements possibly have on the P450 system.
  • Tyramine- or tryptophan-containing foods may cause dangerously high blood pressure when taken at the same time as agents that have properties similar to monoamine oxidase inhibitor drugs (MAOIs). These include protein foods that have been aged or preserved. Specific examples of foods are anchovies, avocados, bananas, bean curd, beer (alcohol-free or reduced), caffeine (large amounts), caviar, champagne, cheeses (particularly aged, processed, or strong varieties), chocolate, dry sausage or salami or bologna, fava beans, figs, herring (pickled), liver (particularly chicken), meat tenderizers, papaya, protein extracts or powder, raisins, shrimp paste, sour cream, soy sauce, wine (particularly chianti), yeast extracts, and yogurt.
  • Caffeine may also interact with Alzheimer's agents; antiasthma agents; antibacterials; anticancer herbs and supplements; antidepressants; antiglaucoma agents; antiobesity herbs and supplements (e.g.; ephedra (ma huang)); antioxidants; antiseizure herbs and supplements; antiulcer herbs and supplements; athletic performance enhancers; B vitamins; bitter orange; caffeine-containing herbs, supplements, foods, and drinks; calcium; calcium-containing foods and drinks; capsicum; coconut products; cola nut; contraceptives; cordyceps; creatine; damiana; danshen; echinacea; genistein; geranium; grapefruit juice; guarana; herbs and supplements that increase urine production; herbs and supplements that lower lipids; herbs and supplements that may lower the seizure threshold; herbs and supplements that mimic sympathetic nervous system activity; herbs and supplements that narrow and widen blood vessels; herbs and supplements that widen airways; high-carbohydrate meals; immune system-lowering herbs and supplements; inotropes; iron-containing foods; iron salts; isoflavone-containing foods; kudzu; Liu Wei Di Huang Wan; magnesium; melatonin; pain relievers; phytoestrogens; potassium; potassium-containing foods; potassium-depleting herbs and supplements; red pepper; sedatives; stimulants; sulfo-carrabiose; tea (black and green); theanine; vitamin B-containing foods; vitamin C; vitamin C-containing foods; vitamin K; vitamin K-containing foods; yerba mate; zinc; and zinc-containing foods.

Authors

Selected References

Natural Standard developed the above evidence-based information based on a systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to www.naturalstandard.com. Selected references are listed below.

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  3. Henderson-Smart DJ, Steer PA. Caffeine versus theophylline for apnea in preterm infants. Cochrane Database Syst Rev 2010;(1):CD000273.
  4. Ker K, Edwards PJ, Felix LM, et al. Caffeine for the prevention of injuries and errors in shift workers. Cochrane Database Syst Rev 2010;(5):CD008508.
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