Allergy to penicillin and its derivatives is the most commonly reported antibiotic allergy in the US. 90% of patients report a penicillin allergy, although, in reality, only 1 out of 10 of those patients are truly allergic.

Many patients are misdiagnosed or self-diagnosed with a penicillin allergy.  Some of these patients presented with a mild rash as a child and were told to avoid the class of medications,  while others may have never even been exposed but stayed away because another family member was allergic. Also, 80% of patients with a true penicillin allergy can “outgrow it” 10 years later.

Patients with an unclear history of penicillin allergy can and should be skin tested. Ruling out a penicillin allergy can save patients a lot of money by allowing them to avoid more expensive drugs that may also be less appropriate for the infection being treated. The penicillin skin test is routinely followed by an amoxicillin oral challenge to confirm tolerance of the medication.