A coffee allergy may be induced by one or more of several coffee components.
The protein found in coffee is one possible reason for an allergic reaction to coffee. Symptoms to coffee proteins are severe, including difficulty breathing, tongue and facial swelling, and shock.
Pesticides and herbicides are another possible culprit of a coffee allergy. Coffee drinkers who notice a reaction when consuming one brand of coffee but not another may be experiencing a chemical sensitivity to pesticides and herbicides. Consuming organic coffee may solve the problem. Symptoms of such a sensitivity include rash and a headache.
Keep in mind that other components of coffee can cause reactions that, while unpleasant, may or may not be indicative of an allergy. For instance, caffeine, whether in coffee, soda, chocolate, or tea, can cause jitters, headache, irritability, and insomnia in many people. These symptoms are not suggestive of an allergy. However, caffeine can cause allergic reactions such as a rash.
Lactose intolerance – again, we are not speaking of an allergy to milk – is another reason one may react to coffee. Obviously, reactions to dairy may be solved by drinking coffee black.
If you suspect an allergy to any of coffee's components, have your allergist test for them.