Caffeine is a chemical found in many different plant species that acts as a central nervous system stimulant and diuretic. It is naturally present in coffee, tea, yerba mate, guarana, and cacao (chocolate) and is added to many beverages, such as cola and energy drinks.
Caffeine is the most widely consumed psychoactive substance in the world and is virtually unrestricted. The United States Food & Drug Administration considers it “generally recognized as safe,” but in extremely high doses, caffeine is known to be toxic and can even cause death.
Does Caffeine Allergy Exist?
True allergy (meaning an IgE antibody-mediated immune system response) to caffeine is rare, but not unheard of. One case report (Caballero et al. 1993) describes a ten-year-old boy who developed urticaria (hives) after consuming caffeinated beverages. A skin prick test and oral challenge test showed he was indeed allergic to caffeine, but not to a related chemical, theophylline. The medical literature shows other sporadic case reports of caffeine causing allergic symptoms, mostly urticaria, but the allergy is clearly not common.
Some Internet sites may claim otherwise. One site asserts that many cases of mental illness are actually caused by caffeine allergy (Whalen 2001). This site alleges — with little support — that caffeine allergy is dramatically more common than recognized by the medical community. It incorrectly compares caffeine allergy (a hypersensitivity reaction) to caffeine toxicity (an overdose reaction) and amphetamine psychosis.
Caffeine Toxicity and Mental Illness
Acute caffeine toxicity is caused by an overdose of caffeine. Some symptoms can resemble symptoms of mental illness, including difficulty sleeping, hallucinations, and mental confusion (Medline Plus 2008). The Diagnostic and Statistical Manual IV of the American Psychological Association includes several caffeine substance disorders.
One study (Kendler et al. 2006) looked at correlations between caffeine intake and psychiatric disorders. The study found that while there is a correlation between a high intake of caffeine and psychiatric disorders such as major depression, generalized anxiety disorder, and panic disorder, the correlation was not one of cause and effect. Instead, external factors such as social and genetic factors made people more likely both to consume large amounts of caffeine and to suffer from mental illness.
The consensus of the medical data available is that while caffeine allergy does exist, it rarely causes serious problems. When caffeine is responsible for symptoms of physical and mental illness, it is usually due to toxicity from overdose and/or dependence, not hypersensitivity resulting from allergy.
- Caballero, T.; C. García-Ara, C. Pascual, J.M. Diaz-Peña, A. Ojeda, 1993. “Urticaria induced by caffeine.” J. Investig. Allergol. Clin. Immunol. 3(3):160-2.
- Kendler, K. S.; J. Myers, C. O. Gardner., 2006. “Caffeine intake, toxicity and dependence and lifetime risk for psychiatric and substance use disorders: an epidemiologic and co-twin control analysis.” Psychological Medicine (Cambridge University Press)
- Medline Plus, 2008. “Caffeine overdose.” U.S. National Institutes of Health Medical Encyclopedia article.
- Whalen, R., 2001. “Caffeine Allergy: Past Disorder or Present Epidemic?” DoctorYourself.com.