This post was written by Vanessa Cavero-Chavez, MD, PPG – Allergy, Asthma & Immunology.
Penicillin Allergy Awareness Day, observed each year on September 28, was created to raise awareness and educate both healthcare professionals and patients about this important health topic.
What is penicillin?
Penicillin is one of the most widely used, effective and safe antibiotics for treating many bacterial infections. Penicillin is classified as a beta lactam antibiotic and works by interfering with the cell wall of bacteria.
What is a penicillin allergy?
A penicillin allergy occurs when there is an abnormal immune response to the drug, resulting in symptoms that can range from mild rashes and itching to severe anaphylaxis with respiratory and systemic compromise, among others. (Anaphylaxis 1-5 cases per 10,000 individuals treated.) This is called IgE mediated reaction.
In the United States, about 10% of the population report being allergic to penicillin, although research shows that 90% of those who identify a penicillin allergy are found not to be truly allergic after appropriate evaluation.
What are the symptoms of a penicillin allergy?
Often, a rash or other symptoms in the middle of an illness are attributed to penicillin when the cause could be an illness. This is commonly seen with viral infections. Over time, this initial reaction may no longer apply, and individuals may safely tolerate penicillin.
Despite the prevalence of reported penicillin allergies, studies reveal that most people outgrow their penicillin allergy or never had a true allergic reaction to begin with. For example, up to 80% of people with a true penicillin allergy lose their sensitivity after 10 years. Many are inaccurately labeled as allergic based on childhood reactions or non-allergic side effects, which can limit their access to the best treatment options when needed.
Less common penicillin reactions (less than 1 case per 10,000 individuals treated) are fever, compromised mucous membranes and skin, and joint pain. These can be severe and life threatening and they require a different approach and immediate medical attention.
How is a penicillin allergy diagnosed?
Allergists play a critical role in accurately diagnosing penicillin allergy, starting with a comprehensive review of the patient’s medical history, nature of symptoms and timeline of the reaction. Based on this information, the allergist will determine the risk of the reaction and the next steps, which could include penicillin allergy testing and/or an oral challenge.
After completing these procedures, the allergist will provide further recommendations. In cases where a patient is found not to be allergic, the allergist will update the patient’s medical records by de-labeling.
The term "de-labeling" refers to the process of removing an incorrect or outdated penicillin allergy status from a patient's medical record after confirming the individual is not allergic. De-labeling is critical for several reasons, including:
- It ensures the patient receives first line treatment for many bacterial infections with penicillin, which is more effective than alternatives.
- It can reduce the risk of antibiotic resistance by allowing care providers to save broad spectrum antibiotics for serious and resistant infections.
- It lowers health care costs, as penicillin is typically a more affordable treatment option compared to alternatives.
De-labeling penicillin allergy improves individual patient care and has a significant impact in public health.
In patients with a confirmed allergy, the allergist will provide guidance and educate the patient on avoiding penicillin and related drugs. The allergist also offers desensitization procedures for patients who require penicillin, despite an allergy in cases of life-threatening infections where no suitable alternatives exist.
If you believe you have a penicillin allergy or you have been labeled as such, we encourage you to talk to your healthcare provider about an evaluation, which may include a referral to the Allergy Clinic.
References
Solensky, R. (2014). Penicillin Allergy as a Public Health Measure. The Journal of Allergy and Clinical Immunology, 133(3), 790-791.
Blumenthal, K. G., Peter, J. G., et al. (2019). Antibiotic allergy. The Lancet, 393(10167), 183-198.
Castells, M. C., & Khan, D. A. (2021). Antibiotic Allergy Testing: What to Know. American Academy of Allergy, Asthma, & Immunology.
