Penicillin Allergy or Sensitivity? Here's What Your Label Really Means 

Fewer than 1% of the population is allergic to penicillin. Yet, the number of people who report being allergic to penicillin is closer to 10%. Why is there a discrepancy? 

Some people’s symptoms may be misinterpreted, and others may have outgrown their penicillin allergy.

Our allergist, Dr. Thomas Fowler, at Allergy and Asthma of Prosper and Celina, Texas, and his team can evaluate you or your family member for a drug allergy and develop a personalized treatment plan. 

Penicillin allergy versus sensitivity 

A true penicillin allergy occurs when your immune system reacts to the medication. An immediate allergic reaction can include hives, swelling, shortness of breath, or anaphylaxis. 

A medication sensitivity or intolerance is different. Penicillin and related antibiotics can cause side effects such as nausea or diarrhea, and while unpleasant, they don’t always mean your immune system is reacting to the medication. 

The timing and type of symptoms you experience provide important clues. Our allergist may ask what medication you took, what symptoms appeared afterward, and how long ago the reaction occurred. 

Can a penicillin allergy disappear? 

Yes. Even if you have a true penicillin allergy, you may not have it forever. 

Around 80% of people with an IgE-mediated penicillin allergy lose their sensitivity after 10 years. So if you were diagnosed with a penicillin allergy at one time, that doesn’t mean you still have it.

Why does your penicillin allergy label matter? 

Penicillin and related drugs are effective and common treatments for many bacterial infections. If your medical history says you’re allergic, that means your healthcare provider will need to find a different antibiotic for you.

That may not sound important, but other antibiotics may be less effective for your infection or contribute to antibiotic resistance, which can make infections harder to treat in the future.

It’s worth finding out if you’re truly allergic to penicillin. 

Testing for a penicillin allergy 

Dr. Fowler can evaluate your medical history and determine the safest way to test you for a penicillin allergy. 

Allergy testing may include skin testing or a supervised oral challenge, depending on your past experience. During an oral challenge, you take a dose of the medication while your allergist watches for signs of a reaction to determine whether the allergy label is still relevant. 

If you or your child has been avoiding penicillin because of a suspected allergy, it may be time to reevaluate. Schedule an appointment at Allergy and Asthma of Prosper and Celina, Texas, to learn whether penicillin allergy testing is a good option for you.