Case Report: Man Develops New Melanoma Weeks After Injecting Melanotan II Bought at a Gym
Doctors in Illinois and Michigan described in JAAD Case Reports a 46-year-old man with a history of melanoma who began daily injections of Melanotan II, an unapproved tanning peptide, bought at a local gym, Gizmodo reported on October 8, 2026. About five weeks later he noticed moles changing size, shape, and color and stopped; a biopsy about a month after that confirmed an early-stage melanoma. He also used tanning beds two to three times a week and had taken anabolic steroids, so the authors could not rule out other causes, and they warned about unregulated peptides promoted on social media.