Are You Allergic to Penicillin, Really?

Unverified penicillin allergy is recognized as a significant public health problem. Up to 10 percent of the population report being allergic to penicillin, according to the Centers for Disease Control and Prevention (CDC).  However, most of those may actually be able to safely use penicillin, either because they never were truly allergic or because they have lost sensitivity over time.

For those who think they are allergic to penicillin, it is important to either confirm the allergy or correctly identify if you can safely take this drug. 9 out of 10 patients reporting penicillin allergy are not truly allergic when assessed by skin testing. Unnecessarily avoiding penicillin leads to higher drug costs for patients and healthcare systems, limited and possibly inferior medical treatments, and possible antibiotic resistance.


What you need to know:

-True penicillin allergy is serious, even life-threatening. Someone with a confirmed penicillin allergy should avoid the entire medication group which includes 15 chemically related drugs.  Ask your physician if you should be prescribed injectable epinephrine, the only treatment that will stop anaphylaxis, a severe, potentially fatal, allergic reaction. 


A reaction to penicillin as a child does not automatically mean you will react as an adult.  Penicillin allergy is not necessarily a life-long condition.  It is best to get tested to confirm.


Symptoms of penicillin allergy may include hives, swelling of the mouth or throat, dizziness, or difficulty breathing.  Hives are often confused with skin rashes that are non-allergy related. Since it may be difficult to tell the difference, and you can’t always get to a doctor right away, take a photograph of the rash to help with the diagnosis.

Alternative antibiotics to penicillin may be less effective in treating your infection, may cause unwanted side effects, or maybe more expensive. Don’t limit your treatment options if it isn’t necessary.


Penicillin allergy testing is safe and reliable. The patient undergoes a series of skin prick tests, with gradually increased amounts of penicillin. A raised bump, or wheal, at the site of the prick, indicates an allergy. If the tests are negative, the next step is an oral challenge to confirm the patient can safely take this drug. These tests should always be conducted by a board-certified allergist trained to recognize and treat potential allergic reactions.


Penicillin allergy testing is available at all AllergySA locations. To schedule an appointment, call 210-616-0882.


September 14,2022 / by Kayla Gomez