Are you allergic to penicillin? Simple test can find out

Odds are, you aren't allergic to penicillin, but there's a simple test to confirm it.

Penicillin is one of the most commonly prescribed antibiotics and is part of a large family of antibiotics, including oxacillin, ampicilin and amoxicillin. Many people are convinced they've had allergic reactions to it.

Allergist Dr. Vaishali Mankad, with Allergy Partners of Raleigh, says adverse reactions are predictable and known, like upset stomach, diarrhea and drowsiness. Allergic reactions are immune based and less common and unpredictable, like an itchy rash, hives, welts, swelling and difficulty breathing.

“Not all adverse drug reactions are allergic reactions to medications. A lot of times people will experience side effects of medications,” Mankad said. “Allergic reactions would potentially occur not with the first time you have ever taken a medication. You usually have actually received the medication before.”

If in doubt, see an allergist. If you’re concerned you have a penicillin allergy, the doctor will take your history, do a physical exam and do a skin test with penicillin to see if you react.

The skin test takes about 45 minutes. About 80 to 90 percent of the tests usually come back negative for penicillin allergies, Mankad said. However, doctors will still give an oral penicillin challenge to make doubly sure you are safe.

Health officials say the skin test can help improve access to the most appropriate antibiotics when people need them most.