Roughly 10% of the population believes they have a penicillin allergy. The truth is that fewer than 10% of people with a reported penicillin allergy actually have one. This topic garnered significant attention recently after an extensive review published by the Journal of the American Medical Association highlighted this important issue. The article was jointly endorsed by the American Academy of Allergy, Asthma and Immunology, the Infectious Diseases Society of America and the Society for Healthcare Epidemiology of America and urges patients diagnosed with a penicillin allergy to schedule an allergy test.
Many patients with a penicillin allergy can expect their sensitivity to penicillin to decrease by about 10% per year. Penicillin drugs are among the safest antibiotics, and verifying that you are no longer allergic can lead to better treatment of future infections, reduced use of antibiotics used as alternatives to penicillin and an overall lower cost of care.
Why Are Patients Often Misdiagnosed?
A patient may be misdiagnosed with a penicillin allergy for a few reasons. They may have experienced drug-related side effects like headaches, nausea or diarrhea, which are not genuine allergic reactions. Alternatively, they may develop a rash. While rashes can be a sign of an allergic reaction, many rashes that occur with amoxicillin or penicillin are actually caused by an underlying viral illness.
Our three board-certified allergists are available to help confirm if you have a penicillin allergy. You can schedule an appointment with Midwest Allergy & Asthma by calling us at (651) 702-0750.
Quick Facts About Penicillin
- What is penicillin?
The penicillin family of antibiotics contains over 15 chemically related drugs (e.g., penicillin, ampicillin, amoxicillin, amoxicillin-clavulanate, methicillin) given by mouth or injection to treat bacterial infections. It is one of the most frequently used antibiotics in the world.
- What are the symptoms of a penicillin allergy?
Penicillin reactions typically occur within an hour of taking the medication. Mild symptoms include hives and swelling of the face, lips or extremities. Anaphylaxis is possible in severe cases and may cause throat swelling, wheezing, coughing, chest tightness, dizziness or loss of consciousness.
- How common is penicillin allergy?
Approximately 10% of patients report an allergy to penicillin. However, most patients (greater than 90%) may not truly be allergic. Most people lose their penicillin allergy over time, even patients with a history of severe reactions like anaphylaxis.
- How do I know if I am still allergic to penicillin?
We use a highly sensitive penicillin skin test to diagnose penicillin allergies. If the test is negative, there is a very high chance that the allergy is no longer present.
- Is penicillin allergy genetic?
There is no predictable pattern to the inheritance of penicillin allergy. You do not need to avoid penicillin if a family member is allergic to penicillin or drugs in the penicillin family.
- Do I need to see an allergist if I know I am allergic to penicillin?
Even if you think you are allergic to penicillin, allergies change over time, and it’s worth discussing your history with one of our allergists. We may suggest testing to help clarify your allergy history.
- I was told I was allergic to amoxicillin. Do I still need to see an allergist?
Amoxicillin is in the same family of antibiotics as penicillin. Your allergist can review your history and perform skin testing to identify an amoxicillin allergy. This testing is similar to penicillin skin testing.
- Is allergy testing painful, and what are the risks?
A skin prick test, also called a scratch test, checks for immediate reactions and is the first step in skin testing. Skin prick testing is usually not painful. You won’t bleed or feel more than mild, momentary discomfort. Intradermal skin testing is the second part of the evaluation and involves injecting the skin. If positive, the test will cause localized itching and redness with swelling at the injection site. Systemic reactions like hives can occur, but are very rare, and allergists are prepared to treat such reactions.
If necessary, your allergist may recommend an oral challenge, where you take penicillin under supervision to test your reaction.
If testing reveals a penicillin allergy but taking the drug is necessary to treat an infection, we’ll begin a supervised desensitization process.
- Do I need to avoid other drugs if I am allergic to penicillin?
This largely depends on your history and the recommendations of your allergist. We generally recommend that you avoid all drugs in the immediate penicillin family (amoxicillin, ampicillin, amoxicillin-clavulanate, dicloxacillin, nafcillin, piperacillin-tazobactam) as well as certain drugs in the cephalosporin class (a closely related class to penicillins). Although the cephalosporins are close relatives of penicillins and share the beta-lactam ring structure, the risk of cross-reactivity remains <5%. Therefore, even with a true penicillin allergy, there is an excellent chance you could tolerate cephalosporins. Your allergist will let you know which drugs to avoid after testing.
Modified from a recent Q&A published by the American Academy of Allergy, Asthma and Immunology:
https://www.aaaai.org/conditions-and-treatments/library/allergy-library/penicillin-allergy-faq