Coffee is a psychoactive drug

CaffeineDrug groupsStimulantsMethylxanthineCaffeine is an active ingredient from the group of stimulants that stimulates the central nervous system, breathing and cardiovascular system and has a performance-enhancing effect. The effects are based on the antagonism at adenosine receptors. Caffeine is a natural substance that is found in coffee, cocoa and black tea, among other things. It is mainly taken as a stimulant against fatigue. Medically, caffeine is used to treat premature apnea and in combination with painkillers for headaches. Possible adverse effects include restlessness, irritability, nervousness, sleep disorders, a rapid pulse, irregular heartbeat, and increased urination. Caffeine can lead to mild addiction.

Synonymous: Caffeine-UmPhEur, Caffeine-MonohydratPhEur, Caffeine-Citrate, Caffeine, Caffeine


Caffeine is commercially available as a medicinal product in the form of tablets, effervescent tablets, lozenges, as a pure powder and as a juice. It is contained in numerous luxury foods; this includes coffee, cocoa, black tea, green tea, matcha, iced tea, mate, soft drinks like Coca-Cola® and energy drinks like Red Bull®. No other psychoactive substance is consumed as frequently in the world as caffeine.

Caffeine content of different drinks, click to enlarge. Illustration © PharmaWiki

Structure and properties

Caffeine (C.8H10N4O2, Mr = 194.2 g / mol) is available as a white, crystalline powder or in the form of silk-like crystals. It sublimates easily and is sparingly soluble in water. However, it dissolves easily in boiling water. Caffeine is a trimethylated xanthine derivative. It is a natural substance and an alkaloid found in coffee, black tea, mate, guarana, cocoa and kola seeds, among others.


Caffeine (ATC N06BC01) stimulates the central nervous system, breathing and cardiovascular system. It keeps you awake, promotes concentration and performance, has diuretic properties and stimulates digestion. The effects are based on the antagonism at adenosine receptors. Caffeine is very well absorbed and quickly crosses the blood-brain barrier into the CNS. It is almost completely metabolized and excreted mainly through the kidneys. The half-life in adults is about 3 to 5 (up to 10) hours.

Mechanism of action of caffeine, click to enlarge. Illustration © PharmaWiki

Indications and areas of applicationContraindications

Caffeine is contraindicated in case of hypersensitivity. Patients with cardiac arrhythmias should avoid high doses. Caution should be exercised with gastric or intestinal ulcers. From our point of view, children should not consume caffeine. The complete precautionary measures can be found in the medicinal product information sheet.


Caffeine is primarily metabolized by CYP1A2. Corresponding drug interactions with CYP substrates, CYP inhibitors and CYP inducers are possible. Other interactions can occur with stimulants, stimulants with caffeine, central depressant drugs and cardiac agents (e.g. sympathomimetics).

unwanted effects
  • Restlessness, irritability, nervousness, sleep disorders, anxiety
  • Fast heart rate, high blood pressure, arrhythmias
  • Increased urination
  • Nausea, indigestion, burning stomach, reflux (GERD)
  • Discoloration of teeth

Regular consumption leads to dependence and tolerance. Withdrawal symptoms such as a caffeine withdrawal headache and irritability may occur if the patient is stopped suddenly. See under coffee withdrawal and caffeine withdrawal.


Caffeine should not be overdosed because it can lead to cardiac arrhythmias and other health problems. Symptoms of overdose include tremor, restlessness, insomnia, nausea, vomiting, rapid pulse, confusion, blurred vision, delirium, convulsions, hypokalaemia and hyperglycemia.

see also

Caffeine citrate solution, energy drinks, coffee, black tea, cocoa, kola seeds, coffee withdrawal, addiction

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Conflicts of Interest: None / Independent. The author has no relationships with the manufacturers and is not involved in the sale of the products mentioned.

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This article was last changed on 3/18/2021.
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