Do You Have a Real Penicillin Allergy?

Posted on by Goodyear Office

An estimated one out of every 10 people in the United States believes they have an allergy to penicillin. While reported allergies are common, clinicians found that less than 1% of those who thought they had it were actually allergic to penicillin.[1]  

Why Penicillin Allergies Are Frequently Misdiagnosed

Prescription bottle of penicillin on a blurred background.

Penicillin allergy misdiagnoses often stem from a childhood infection. When you develop an infection, you’ll display symptoms that align with those of a drug allergy, such as a fever or congestion. If your doctor treated you with a penicillin drug, they may have misattributed the reaction to the medication.

Can True Penicillin Allergies Fade?

Another common reason adults think they have penicillin allergies when they don’t is that a true allergy often fades over time. Researchers found that 80% to 90% of patients who tested positive for a penicillin allergy in the past can expect a 10% decrease in sensitivity each year.[2] Following that math, many patients will test negative for the allergy 10 years after their initial test.

What Are the Signs of a True Penicillin Allergy?

Allergies are an exaggerated immune system response to a substance that is otherwise harmless. To protect the body from a perceived threat, it releases chemicals into the bloodstream, causing symptoms such as swelling, inflammation, rashes, hives, itchiness, watery eyes and more. People with penicillin allergies experience these and other symptoms when they take penicillin.

The biggest danger is the possibility of anaphylaxis. This serious and potentially deadly side effect causes breathing difficulties, wheezing, dizziness, weak or rapid pulse, nausea, vomiting, hives and loss of consciousness. Anaphylaxis is a medical emergency requiring immediate treatment with an epinephrine injection.

The Importance of Allergy Testing

Penicillin drugs are some of the most widely used antibiotics. Confirming whether an allergy exists will ensure you get the safe and effective treatment you need.

If you were diagnosed with a penicillin allergy as a child or experience symptoms you believe to be the result of the medication, contact Goodyear Office to schedule an allergy test with one of our specialists.

[1]   Centers for Disease Control and Prevention. (n.d.). Clinical signs. https://www.cdc.gov/antibiotic-use/hcp/clinical-signs/index.html [cdc.gov]

[2] Hsu J, Vellaichamy Manian D. Penicillin Allergy. [Updated 2026 Apr 19]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK459320/