Azathioprine-induced alopecia: a rare adverse event, early marker of myelotoxicity

Though not exempt from adverse events, azathioprine (AZA) is an inexpensive and effective drug in the induction and maintenance treatment of patients with inflammatory bowel disease. We present the case of a 20-year-old female patient with left-side ulcerative colitis in whom AZA was started at a dose of 1.5 mg/kg/day due to dependence on corticoids (thiopurine methyltransferase activity: 14.9 U/mL). Two weeks after starting treatment she began to report excessive hair loss, resulting in an almost complete loss of scalp hair.