Zileuton is approved in the US for the prophylaxis and chronic treatment of allergic asthma; it is also used to treat chronic non-allergic reactions such as NSAID-induced non-allergic lung, nose, and conjunctiva reactions as well as exercise-induced asthma. Zileuton has shown some beneficial effects in clinical trials for the treatment of rheumatoid arthritis, inflammatory bowel disease, and psoriasis. Zileuton is currently undergoing a phase II study for the treatment of acne vulgaris (mild-to-moderate inflammatory facial acne) and a phase I study (see Clinical trial#phases) combining it with imatinib for treating chronic myeloid leukemia.