Penicillin allergies seem to be surprisingly common – or are they?
One in ten Canadians report having a penicillin allergy, but very often, an allergic reaction is unrelated to having received penicillin. The reaction could have been caused by a number of other factors, like food or another medication.
In fact, a recent study led by Sunnybrook found that patients who had previously reported a penicillin allergy are often able to receive the drug after a simple bedside skin test known as BLAST, which stands for beta-lactam allergy skin testing.
“The majority of inpatients who report an allergy to penicillin could likely tolerate it if they received it. Doing a bedside allergy skin test helped us determine who those patients were,” says Dr. Jerome Leis, lead study author and Medical Director of Infection Prevention and Control at Sunnybrook.
What’s the big deal if you mistakenly think you have a penicillin allergy?
If you end up in the hospital with a life-threatening infection, the best (or only) treatment option may be penicillin.
Declaring an allergy to penicillin means not being able to access more than 20 drugs from the arsenal of potential treatments. You may receive less effective antibiotics to treat your infection, and experience poorer outcomes as a result.
“In addition to some of the more toxic side effects associated with alternate therapy to penicillin, some of these alternative drugs don’t reach the site of infection. Limiting the use of those alternate therapies also reduces antibiotic resistance,” says Lesley Palmay, study co-author and Infectious Diseases Consult Service Pharmacist at Sunnybrook.
In the Sunnybrook study, 99% of participants who previously reported a penicillin allergy were treated with penicillin without complication. These results show that bringing skin testing to the bedside improves treatment of serious infections.
Bedside skin testing is now standard practice at Sunnybrook. “Now, the right patient can receive the right antibiotic for their infection, without fear of an allergic reaction,” says Dr. Leis.
How to be sure whether or not you have a penicillin allergy
Many people outgrow their penicillin allergy, or may be able to receive the drug in controlled doses. Are you one of them?
Ask your family doctor to review your history and decide whether you are a candidate for allergy testing. Testing involves surface skin testing, followed by oral administration of a penicillin antibiotic over the course of six hours in the Drug Safety Clinic at Sunnybrook.