In a drug allergic reaction, the immune system responds inappropriately to a medication by developing an adverse immunologic response that involves the release of histamine and other chemicals from the tissues. Symptoms can vary from mild rash and itching to a severe reaction including hives, swelling, abdominal discomfort, difficulty breathing, and loss of consciousness.
A drug allergy can be diagnosed by careful review of a patient’s history and medical records. Penicillin allergy is among the most common drug allergies and can be diagnosed by allergy skin testing. In the case of penicillin allergy, this sensitivity may be lost over time as demonstrated by negative allergy skin testing. In-office oral challenge to penicillin is often subsequently performed which, if tolerated, may allow for penicillin derivatives to be safely used again. Depending on the patient need and relative risk, oral challenge to other medications can also be performed in the office setting.