Why you may not be allergic to medications – Even if you think you are

September 19, 2016

“Are you allergic to any medications?”

You’ve likely been asked this dozens of times over the years. Ten percent of the population report that they’re allergic to the antibiotic penicillin. However, 90 percent of people who think they’re allergic to penicillin actually aren’t.

Why do so many people think they’re allergic to penicillin? I’ve had patients tell me, “Well, my mom said I had an allergic reaction to penicillin when I was little.” It was noted on their medical chart and no one questioned it again. However, they may not have been allergic in the first place, or they may have outgrown the allergy by adulthood.

Any drug allergy can be life-threatening, and should be taken seriously. However, a mistaken drug allergy, including penicillin, also can have serious consequences, possibly leading to being prescribed drugs that may be less effective or more expensive. People who were told they have a drug allergy – especially in childhood – may benefit from consulting with an allergist.

Misdiagnosing and outgrowing a penicillin allergy

An example: Your child gets an ear infection and is prescribed a penicillin- based antibiotic. Soon after, they develop a rash and it’s assumed that the penicillin caused it. However, viral infections often cause rashes – called viral exanthems – in children and infants. It can be difficult to know what caused the rash – the penicillin or the virus – and your child could go through life thinking they have an allergy they don’t actually have. This is where penicillin skin testing can be helpful.

Some people may have a true allergy to penicillin. However, penicillin allergy may also be outgrown, meaning the immune system “forgets” about it. In fact, one study showed that only about 20 percent of people who had an allergic reaction to penicillin were still allergic 10 years later.

A drug’s side effects – such as nausea or diarrhea – are sometimes mistaken for an allergic reaction. Unlike an allergy, you may not need to immediately quit taking the drug if you experience a side effect. Your doctor may instead lower the drug’s dose or suggest something to ease the symptoms.

Why and when should you get penicillinallergy testing?

Patients who have a penicillin allergy listed on their charts often have significantly longer hospital stays, more antibiotic use, and increased risk of developing a drug-resistant infection such as methicillin-resistant Staphylococcus aureus (MRSA). Patients with penicillin allergy often are prescribed different antibiotics that may cause more side effects. Therefore, if you can get penicillin removed from your list of allergies, it can have positive implications for your health.

If a number of years has elapsed since you’ve had an allergic reaction to a penicillin, it might be worth talking with an allergist. We can do a simple skin test for a penicillin allergy. If you’re nervous, don’t be. It’s just a little poke on the skin. I describe it as touching the back of an earring or a safety pin. For drugs that we don’t have a skin test for, such as sulfa drugs, we may test you by giving you a low “test dose” of the drug in a safe, controlled environment. 

We only have good testing for penicillin, but if you have a number of antibiotic allergies, it’s worth discussing them with an allergist. Sometimes we may reintroduce a drug in a controlled way to prove that you are not allergic.

If you’ve gone through life thinking you’re allergic to a drug, there may be a chance you can check “no” the next time you fill out a form asking about allergies. To schedule an allergy consultation, call 585-922-8350, or go online to find our hours and locations.
Categories: Allergy
Topics: Drug Allergies