A history of penicillin allergy needs to be clarified prior to use. Patients with a history of allergy should avoid penicillin if possible, while those without a history of allergy will require a skin test. In adults or children, skin testing is required before applying penicillins, whether by different routes of administration, such as oral, intravenous or intramuscular injection. After 72 hours of discontinuation, a new skin test should be performed and a negative skin test should be performed before penicillin is administered. However, it should be noted that even if the penicillin skin test is negative, rapid allergic reactions may occur in 1% to 3% of patients.