Introduction Literature supports the utility of skin testing in Progesterone hypersensitivity (PH) for decision making, but we describe false-positive from reported non-irritating progesterone testing concentrations. Case Description 39-year old female presents recurrent erythema, pruritus, diaphoresis, dyspnea, palpitations, stomach cramping and presyncopal sensation prior to menstruation. Progesterone skin testing, including prick testing (SPT) and intradermal (ID) was performed. SPT was negative and ID positive on patient and two controls (table 1). Oral antihistamines twice daily controlled her premenstrual symptoms concerning for PH. 19-year old female presented two years ago with a reaction to medroxyprogesterone. A rash developed the morning after the first dose. Within hours of the second dose, the rash spread with wheezing and throat closure sensation. She was skin tested to progesterone in sesame oil with ID positive on patient and two controls (table 1). Two years later, skin testing was repeated based on using benzyl alcohol as diluent. SPT was negative; ID was positive on patient and two controls. She underwent a four-day graded challenge without reactions. Discussion Progesterone is an oil-based medication that is difficult to dilute. In the literature, benzyl alcohol and sterile olive oil have been used for dilution with 50% of patient's testing being negative. In our experience, the 0.5 mg/mL intradermal concentration is irritating with either diluent and provided false positive results. As skin testing may not elucidate sensitization and clarify PH management, patient history remains of greatest importance in diagnosis with physician-supervised drug challenge as the procedure of choice in patients with a questionable history.