Allergy to penicillin is a subject of great concern to any physician who may be called upon to treat patients for infections. The number of people exposed to penicillin is very difficult to determine, as is the incidence of allergic reactions, but it has been variously estimated that in the United States from 2.5 to 15 million persons are allergic to penicillin, and several hundred die each year of allergic reactions to this antibiotic. A history of allergy to penicillin can be elicited in from 2% to 20% of patients, and 1% to 10% of patients with no such history will have a reaction on therapeutic challenge.
Although the potential seriousness of the problem has been appreciated for more than 25 years, meaningful investigations into the mechanisms involved, attempts to develop useful, safe, and reliable methods of diagnosis, and efforts to derive means of coping with these reactions have been