There is generally no way to prevent development of a drug allergy.

If you have a known drug allergy, avoiding the medication is the best way to prevent an allergic reaction. You may also be told to avoid similar medicines. For example, if you are allergic to penicillin, you should also avoid amoxicillin or ampicillin.

In some cases, a doctor may approve use of a drug that causes an allergy if you are pretreated with corticosteroids (such as prednisone) and antihistamines (such as diphenhydramine). Do not try this without a doctor’s supervision. Pretreatment with corticosteroids and antihistamines has been shown to prevent anaphylaxis in people needing to get iodinated x-ray contrast dye.

Your doctor may also recommended “densensitization.” This procedure must be done under close medical supervision. It involves giving very small doses of the medicine over a specific period of time. Do not try this without your doctor.