Is it really a penicillin allergy? | Allergy & Asthma Specialists

When it comes to fighting infections, penicillin is many doctors’ go-to solution. But why? For starters, the majority of infections faced by the general public are viral, which means antibiotics should not be prescribed. In comes penicillin. This antibacterial drug is highly effective against common illnesses like strep throat and ear infections. It’s also more affordable compared to alternatives.

However, for 10% of U.S. patients labeled with a “penicillin allergy,” this helpful drug is seemingly off the table…or so they’ve been led to believe! Research shows that the vast majority of these individuals — more than 90% according to the American Academy of Allergy, Asthma & Immunology (AAAAI) — may not truly be allergic to penicillin, and this mislabeling could have significant implications for their healthcare.

So, is your “allergy” really an allergy at all? How can you tell the difference? Here’s what we know.

Misdiagnosis and Mislabeling

For many patients, what is perceived as an allergic reaction may actually be a side effect or an unrelated symptom. Misdiagnosis commonly occurs when medication reactions such as nausea, headache or a rash are mistaken for an allergy symptom. In reality, only a fraction of these patients have a true allergic reaction to the drug.

In fact, 80% of people who once had a genuine penicillin reaction lost sensitivity after 10 years and could now tolerate its use. This even includes those who had a serious, anaphylactic reaction.

So, why does this matter?

The Benefits of Correct Diagnosis

Knowing whether or not you are genuinely allergic to penicillin can bring you several benefits:

Improved Patient Outcomes: Penicillin is one of the most effective antibiotics for treating a range of bacterial infections. By clearing patients to use penicillin, healthcare providers can offer more effective treatments.
Reduced Healthcare Costs: Penicillin and its related antibiotics are generally less expensive than second-line alternatives. When patients are mislabeled as allergic, they may be prescribed costlier drugs that are less effective.
Fighting Antimicrobial Resistance: Overuse of second-line antibiotics can contribute to the rise of antimicrobial resistance. Penicillin-based antibiotics are often more targeted and effective, reducing the likelihood of developing resistant bacteria.

“All health care professionals should refer individuals with ‘PCN allergy’ to the allergist for further evaluation,” said Dr. Susan P. Raschal of Family Allergy & Asthma. “Any individual labeled ‘PCN allergic’ should seek the expertise of an allergist to determine if they have a penicillin allergy. When we work together, we can make a difference!”

Find Answers With an Allergy Test

If you’re listed with a penicillin allergy but haven’t experienced a true allergic reaction, a penicillin allergy evaluation can clarify your diagnosis. Based upon a thorough history, your allergist can determine if skin testing or an oral allergy challenge is warranted.

More often, an allergy skin test is often recommended. During this test, a board-certified allergist pricks the forearm with a small dose of penicillin. If you are allergic, an itchy red bump will appear within minutes. This test is beneficial for high-risk patients, such as those with a history of severe reactions (anaphylaxis) or multiple drug allergies.

If you do not show symptoms, your allergist will conduct an allergy oral test to rule out an acute allergy. This safe test involves giving a patient a small dose of an allergen to observe if an allergic reaction occurs. Most patients (about 3.5%) pass the test without any issues and can be cleared by their allergist to safely use penicillin in the future.

However, there are some reactions where testing for penicillin allergy is not recommended. These Severe Cutaneous Adverse Reactions (SCAR) – late-onset reactions to penicillin – include the following:

Your allergist will be able to determine if you have had a reaction that results in one of those above conditions and help you proceed accordingly. Alternatively, your allergist may choose to treat through minor reactions like rash or serum sickness.

Signs of a True Penicillin Allergy

A true allergic reaction to penicillin can involve several systems in the body. The most common symptoms may include:

Skin: Hives, rash, itching or angioedema (swelling beneath the skin)
Respiratory: Wheezing, coughing or difficulty breathing
Gastrointestinal: Nausea, vomiting or abdominal pain
Cardiovascular: Dizziness, fainting or chest pain
Other: Swelling of the lips or tongue, itchy eyes, nasal congestion and more

These reactions can occur within an hour of taking the medication or be delayed. In rare cases, anaphylaxis can occur, requiring immediate medical attention.

Your allergist will likely ask a series of questions to determine if penicillin is truly to blame for your reaction.

How long ago was the possible reaction?
What medication were you taking?
How long have you been taking the medication until the adverse event happened?
What were the details of the reaction?
Have you taken the medication before?
Has the medication been taken since?
How long ago was the possible reaction?

Find the Truth (and Peace of Mind)

Are you ready to uncover the truth behind your allergy symptoms? Our board-certified allergy specialists are ready to help you live comfortably and allergy-free. Contact us today to schedule your next allergy appointment.

About Allergy & Asthma Specialists

Allergy & Asthma Specialists is affiliated with Family Allergy & Asthma, a network of allergy and asthma doctors dedicated to providing high-quality, reliable and lasting allergy relief. Allergy & Asthma Specialists serves patients at eight Philadelphia-area locations, including the communities of Blue Bell, Collegeville, Doylestown, Jenkintown, King of Prussia, Landsdale, Philadelphia and Pottstown. For more information, visit allergyphilly.com, and follow Allergy & Asthma Specialists on Facebook, Instagram and X.