Acne can be caused by acne, folliculitis, contact dermatitis and other diseases. 1. Acne: the body’s androgen secretion is exuberant, the hair follicle greasy secretion increase, acne propionate feeling infection, the hair follicle hyperkeratosis, will induce the brain door long acne. 2. Folliculitis: local hair follicles are infected by external pathogenic bacteria or fungi, forming an inflammatory reaction of the hair follicles can also cause the appearance of acne. 3. Contact dermatitis: local skin contact with external sensitizers to form an allergic reaction, may also lead to acne, accompanied by itching, skin redness and swelling and other symptoms. There may be other reasons for acne on the brain need to go to the hospital for examination first, to clarify the cause of the disease and follow the doctor’s instructions for treatment.