We retrospectively evaluated the effect of penicillin adverse drug reaction (ADR) labeling on surgical antibiotic prophylaxis. Cefazolin was administered in 86% of penicillin ADR-negative (−) and 28% penicillin ADR-positive (+) cases. Broad-spectrum antibiotic use was more common in ADR(+) cases and was more commonly associated with perioperative adverse drug events.