, Volume 94, Issue 4, pp 437-451

First online:

Caffeine physical dependence: a review of human and laboratory animal studies

  • Roland R. GriffithsAffiliated withDepartment of Psychiatry and Behavioral Sciences, The Johns Hopkins University School of Medicine
  • , Phillip P. WoodsonAffiliated withDepartment of Psychiatry and Behavioral Sciences, The Johns Hopkins University School of Medicine

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Although caffeine is the most widely used behaviorally active drug in the world, caffeine physical dependence has been poorly characterized in laboratory animals and only moderately well characterized in humans. In humans, a review of 37 clinical reports and experimental studies dating back to 1833 shows that headache and fatigue are the most frequent withdrawal symptoms, with a wide variety of other signs and symptoms occurring at lower frequency (e.g. anxiety, impaired psychomotor performance, nausea/vomiting and craving). When caffeine withdrawal occurs, severity can vary from mild to extreme (i.e. incapacitating). The withdrawal syndrome has an onset at 12–24 h, peak at 20–48 h, and duration of about 1 week. The pharmacological specificity of caffeine withdrawal has been established. The proportion of heavy caffeine users who will experience withdrawal symptoms has been estimated from experimental studies to range from 25% to 100%. Withdrawal symptoms have been documented after relatively short-term exposure to high doses of caffeine (i.e. 6–15 days of ≥600 mg/day). Although animal and human studies suggest that physical dependence may potentiate the reinforcing effects of caffeine, human studies also demonstrate that a history of substantial caffeine intake is not a necessary condition for caffeine to function as a reinforcer. The similarities and differences between caffeine and classic drugs of abuse are discussed.

Key words

Caffeine Caffeinism Coffee Tea Physical dependence Withdrawal Reinforcer Drug self-administration Subjective effects Drug dependence Drug abuse Humans Animals