Allergic Reactions to Caffeine

Urticaria rash (hives) on legs

Caffeine is a stimulant consumed by millions of people in the United States every day. It is found naturally in the seeds of coffee and cocoa plants, and in tea leaves. When consumed, caffeine stimulates the central nervous system, improves the function of the heart and lungs, increases the contraction of blood vessels, and acts as a diuretic (increases the formation of urine).

Many of us cannot make it through our day without consuming a certain amount of caffeine, found mostly in beverages such as coffee, tea, cola, energy drinks, and chocolate. Caffeine is also found in prescription and over-the-counter headache remedies, as well as in ​No-Doz Alertness Aid capsules. For the majority of people, a moderate amount of daily caffeine intake is safe, improves mood and alertness, and aids in productivity.

Allergic Reactions to Caffeine

Allergic reactions to caffeine can occur, however, they are rare. There are a number of case reports in the medical literature regarding allergic reactions, mostly urticaria (hives), after the consumption of caffeine. The most striking report, published in 2003 by researchers in Spain, details the case of a 21-year-old man who experienced anaphylaxis after drinking coffee or multiple cola drinks. Decaffeinated colas and other foods containing smaller amounts of caffeine, such as tea and chocolate, did not cause him to experience allergic reactions.

Allergy skin testing and allergy blood testing for IgE allergic antibody were both positive for caffeine.

A number of other studies have described people who have experienced various allergic reactions as a result of consuming caffeine, most commonly urticaria and angioedema. Most of these studies showed that the people with caffeine allergy showed positive skin testing to caffeine, and some even proved the allergy through reproducing allergic symptoms with an oral challenge to caffeine.

Some researchers on caffeine allergy have suggested that people who experience hives from an unknown cause could actually be experiencing allergic reactions to caffeine-containing foods. Certainly, it may be reasonable for people with chronic hives from an unknown cause to stop consuming caffeine-containing foods for a period of time (such as a week or so) to see if the hives resolve.

Caffeine Allergy or Non-Allergic Food Intolerance?

It is not known how common allergic reactions are to caffeine. Most people who experience symptoms after consuming caffeine, such as headaches, rapid heart rate, gastrointestinal upset (such as nausea or diarrhea), jitteriness, and insomnia are more likely experiencing non-allergic food intolerance or pharmacologic side effects of caffeine.

The diagnosis of caffeine allergy would be suggested by the presence of allergic symptoms, typically within minutes to a few hours after the consumption of food or drink containing caffeine. Allergy testing to caffeine would be required to definitely make a diagnosis of caffeine allergy, and this may best be done with a caffeine tablet (such as skin testing to a ground-up No-Doz tablet), rather than simply a food or beverage containing caffeine.

Avoidance of caffeine-containing foods would be the best way to prevent symptoms of caffeine allergy, although treatment of immediate symptoms of caffeine allergy may include the use of antihistamines and injectable epinephrine.

Learn about allergic reactions to coffee.


Infante S, et al. Anaphylaxis Due to Caffeine. Allergy. 2003; 58:680-90.

Hinrichs R, et al. Caffeine Hypersensitivity. Allergy. 2002; 57(9):859-60.