A drug allergy is the abnormal immunologic reaction to a medication.

Certain medications that are likely to produce allergic reactions include antibiotics such as penicillin, anticonvulsants, anesthetic agents, monoclonal antibody therapy, chemotherapy agents, and vaccines. The most common signs and symptoms of drug allergy are hives, swelling, or fever, and may cause anaphylaxis.

Drug allergies are commonly over-diagnosed, and your allergist will help determine if you truly need to avoid the medication in question, or if this could again be safely used in the future.