The main causes of forehead acne are acne, folliculitis and other diseases. 1. Acne is a chronic inflammatory skin disease that manifests itself in a variety of clinical forms, including pimples, papules, pustules, and nodules, etc. Its causes include genetics, androgen secretion levels, Propionibacterium acnes infections, etc., and it is also affected by diet and emotional factors, etc. Folliculitis is an acute inflammatory disease located around the hair follicles. 2. Folliculitis is an acute inflammatory disease located around the hair follicles, which is mainly manifested as small pustular papules around the hair follicles in the clinic, and its causes are mainly related to abnormal immunity, poor skin hygiene and other factors, as well as affected by dietary factors. Due to the individual differences in clinical manifestations, the specific situation requires a doctor’s consultation.