Other names: Cafeina, cafeina, caffeine, coffein, coffeinum, guaranin, koffein, methyltheobromin, methyltheobromine, 1, 3, 7- trimethyl- 2, 6 (1H3H)- purindion, 1,3,7-trimethylxanthine ,thein, theine

Substance type: purine

Caffeine was first isolated from coffee beans (Coffea arabica) and named after the genus. However, this stimulating substance actually occurs in many plants. Caffeine has stimulating effects upon the central nervous system because it inhibits the enzyme phosphodiesterase, which inhibits the conversion of endogenous substances (cAMP into AMP). This stimulation is usually accompanied by an increase in heart activity, increased urgency of micturition, sensations of heat, and a rise in body temperature. Vasodilation in the brain dispels tiredness and perception becomes mor acute. A normal effective dosage is about 100 mg (equal to approximately one cup of strongly brewed coffee). Undesirable side effects begin to appear at 300 mg unless one is used to this level of consumption. There have been repeated reports of “caffeine addcition” in the United States (Weil 1974). Overdoses of caffeine tend to be unpleasant in nature: (cf. Ilex guayusa):

Acute caffeine poisoning causes inebriation like states of excitation accompanied by ringing in the ears, headaches, dizziness, racing heart, muscle tension, insomnia, restlessness, confusion, deliria, cramps, urge to vomit, diarrhea, urgency of micturition. (Roth et al. 1994, 786*)

It has occasionally been suggested that Catha edulis contains caffeine, but this assumption has never been confirmed and can now actually be ruled out.
Caffeine is used medicinally to treat heart weakness, neuralgia, headaches, asthma, and hey fever and is also administered in homeopathic preparations. It is used as an antidote for poisonings and overdoses of alcohol, nicotine, morphine and THC.

-Page 820, The Encyclopedia of Psychoactive Plants: Enthnopharmacology and Its Applications by Christian Ratsch (1998)

Related Reading:

Plants Containing Caffeine