As a pharmacist, when I dispense medication, it’s my responsibility to ensure that the medication is safe and appropriate for the patient. There are numerous checks we go through including verifying the dose, ensuring there are no interactions with other drugs, and verifying the patient has no history of allergy to the product prescribed. Asking about allergies is a mandatory question for every new patient.
Penicillin is one of the oldest antibiotics still in use despite widespread bacterial resistance. Multiple analogs of penicillin have been developed to change its effectiveness, or improve its tolerability. And other classes of antibiotics (e.g., cephalosporins) share some structural features with penicillin. These products are widely used for both routine and serious bacterial infections. Unfortunately, allergies to penicillin are widely reported. Statistically, one in ten of you reading this post will respond that you’re allergic to penicillin. Yet the incidence of anaphylaxis to penicillin is estimated to be only 1 to 5 per 10,000. So why do so many people believe they’re allergic to penicillin? Much of it comes down to how we define “allergy.”