Penicillin Allergy

Skin Testing

When done correctly, PCN skin testing is highly predictive of serious, anaphylactic reactions.

The negative predictive value of penicillin skin testing for immediate reactions approaches 100%

Rarely (1-3%), skin test negative patients may get mild hives and itching following penicillin administration but these RESOLVE with oral antihistamines.

Skin test positive patients are at high-risk (50-75%) for serious IgE-mediated reactions with PCN exposure, and should avoid PCN agents or undergo a PCN desensitization procedure if no alternative agent exists.

Skin tests cannot predict non-IgE mediated dermatologic reactions (delayed morbilliform rash or SJS/TEN), GI disturbances, or drug fevers.

Allergy consultation is advised