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.

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.

evidence table

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 provider.
Apnea (Grade: A)
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.
Cognitive performance (Grade: A)
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.
Exercise performance (Grade: A)
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.
Respiratory disorders (Grade: A)
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.
Headaches (Grade: B)
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.
Attention-deficit hyperactivity disorder (ADHD) (Grade: C)
There is conflicting evidence supporting the use of caffeine in the treatment of ADHD in children. Additional research is needed in this area.
Diabetes (Grade: C)
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.
Intermittent claudication (Grade: C)
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.
Kwashiorkor (children) (Grade: C)
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.
Liver disease (Grade: C)
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.
Mood (Grade: C)
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.
Obsessive compulsive disorder (OCD) (Grade: C)
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.
Pain (Grade: C)
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.
Parkinson's disease (Grade: C)
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.
Skin conditions (wrinkles, stretch marks, cellulite) (Grade: C)
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.
Stroke (Grade: C)
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.
Weight loss (Grade: C)
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.