Penicillin allergy

Introduction

Penicillin and related antibiotics are effective for treating bacterial infections. But if you have a penicillin allergy, taking these drugs can be dangerous.

Penicillin and related antibiotics can cause an allergic reaction in some people. Not all adverse reactions to penicillin are a sign of an allergic reaction. True allergic reactions involve the immune system and can cause signs and symptoms that range from an annoying rash to a life-threatening reaction (anaphylaxis) with low blood pressure and trouble breathing.

It isn't clear why some people develop penicillin allergy while others don't. Treating an allergic reaction may require taking medications or, in the case of a serious reaction, emergency care.