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caffeine (kăfēnˈ), odorless, slightly bitter alkaloid found in coffee, tea, kola nuts (see cola), ilex plants (the source of the Latin American drink maté), and, in small amounts, in cocoa (see cacao). It can also be prepared synthetically from uric acid. While relatively harmless, it is the most commonly used mind-altering drug in the world. When used in moderation, caffeine acts as a mild stimulant to the nervous system, blocking the neurotransmitter adenosine and resulting in a feeling of well-being and alertness. It increases the heart rate, blood pressure, and urination and stimulates secretion of stomach acids; excessive intake can result in restlessness, insomnia, and heart irregularities. The effects of caffeine vary from person to person, as people excrete it at different rates. Physical dependence and unpleasant symptoms upon withdrawal (headache, fatigue, depression) are common in regular caffeine users.


See B. A Weinberg and B. K. Bealer, The World of Caffeine (2001).

The Columbia Electronic Encyclopedia™ Copyright © 2022, Columbia University Press. Licensed from Columbia University Press. All rights reserved.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



a central nervous system stimulant; trimethylxanthine, an alkaloid found in tea leaves, coffee beans, and kola nuts and obtainable synthetically.

Caffeine is administered in tablet form in cases of central nervous system depression, weak cardiac activity, narcotic intoxication, hypotonia, and migraine. A solution of caffeine and sodium benzoate, containing 38 percent pure caffeine and administered subcutaneously, has similar pharmacological properties and indications.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


(organic chemistry)
C8H10O2N4·H2O An alkaloid found in a large number of plants, such as tea, coffee, cola, and mate.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.


, caffein
a white crystalline bitter alkaloid responsible for the stimulant action of tea, coffee, and cocoa: a constituent of many tonics and analgesics. Formula: C8H10N4O2
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
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