Risk of Allergic Reactions to Recurrent Intravenous Penicillin Administration in Penicillin Skin Test Negative Patients.

Background: Patients with a history of penicillin allergy who are found to be skin test negative to penicillin are able to tolerate repeated oral doses of penicillin with low rates of resensitization. However, the resensitization rate after repeated doses of intravenous penicillin is less clear.

Objective: We sought to evaluate the risk of allergic reactions to repeated doses of intravenous penicillin in patients who previously reported penicillin allergy and were found to be penicillin skin test and oral challenge negative.

Methods: A retrospective review was conducted between 2010 and 2016 of adult patients who were treated at our academically affiliated hospitals. Patients included in the review had negative penicillin allergy testing and were treated with 2 or more courses of intravenous penicillins. Charts were evaluated to identify any adverse drug reactions.

Results: Thirty-two patients met our inclusion criteria. The index penicillin-associated reactions ranged from rash to hypotension and were, for the most part, remote as 75% had reported reactions more than 10 years previously. More than 50% of patients received 3 or more courses of intravenous penicillins. The most frequently repeated intravenous penicillin overall was piperacillin/tazobactam. Thirty-two patients received a total of 111 courses of intravenous penicillins and none developed an immediate hypersensitivity reaction.

Conclusions: In patients who report penicillin allergy and have negative penicillin allergy testing, repeated administration of intravenous penicillin antibiotics appears to be safe. Larger prospective studies should be performed to confirm these observations.