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Always Been Allergic to Penicillin? You Actually Might Not Be!

Dr. Angela Chan, Allergy & Immunology

December 29, 2021

Always Been Allergic to Penicillin? You Actually Might Not Be!

Does this sound familiar? Once upon a time you had an adverse reaction after taking penicillin and were diagnosed as allergic; as a result, that allergy has been on your chart for years. But what if that is no longer an accurate diagnosis?

We’re finding more and more prevalence of such a scenario. Indeed, penicillin allergy is confirmed in less than 10% of patients with a reported penicillin allergy in the United States!

These inaccurate labels of penicillin allergy occur because of the overdiagnosis of antibiotic allergies when evaluating childhood rashes and other adverse reactions -- and because even a true medical allergy to penicillin can wane with time. The impact is significant for both patients and the overall healthcare system, as inaccurate penicillin labels are associated with poor outcomes including:

  • Inappropriate antibiotic prescribing and overuse of second-line antibiotics that may be less effective and more costly
  • Increased length of hospital stays
  • Increased risk of infection with multi-resistant organisms
  • Increased rates of Clostridium difficile diarrhea
  • Increased mortality

Though penicillin has been around since the 1940s, it is still a very useful drug and is one of the most frequently used classes of antibiotics. The penicillin family of antibiotics contains over 15 chemically related drugs (including penicillin, ampicillin, amoxicillin, amoxicillin-clavulanate) that are given for the treatment of many bacterial infections, such as that of the middle ear, sinuses, respiratory tract (including pneumonias), urinary tract, skin/soft tissue, dental and other serious infections.

Penicillin allergy de-labeling is important because it is a cost-effective strategy that simultaneously protects patients from adverse outcomes and reduces healthcare costs.

So how can you find out if you’re still allergic?

First, you will discuss your history and prior reaction to penicillin (or another chemically related drug in the penicillin family) with your allergist. Depending on the type of reaction you experienced, you may be an appropriate candidate for penicillin testing.

Testing is typically a two-step process, consisting of:

  • A skin test, where we use several different dilutions of penicillin. If results from skin testing are negative, we move on to:
  • A drug provocation test, where you will be given an oral dose of penicillin or amoxicillin in the allergy office and observed for two hours to confirm antibiotic allergy or current tolerance.

More recently, some studies have supported the use of direct drug provocation tests without preceding skin testing for both pediatric and adult patients who report a low-risk historical reaction to penicillin. When you consult with your allergist, they can determine whether you would be an appropriate candidate to go straight to the drug provocation test.

I’m always on the lookout for penicillin allergy labels when I see patients and I encourage them to undergo evaluation and potentially testing, if appropriate, to see if their label is truly accurate. Even if the type of allergic reaction you have experienced to penicillin does not warrant testing, of if your penicillin allergy is confirmed from testing, we can discuss alternative options if the need for antibiotics arises. This will go a long way toward improving your care should you need this antibiotic in the future.

Dr. Angela Chan

Dr. Angela Chan is a board-certified pediatrician and allergist-immunologist at the Scarsdale Medical Group in Harrison. For an appointment, please call 914-723-8100.