Acne in the hair may be a sign of acne, or it may be caused by folliculitis and other diseases. 1. Acne: Acne in the hair may be caused by elevated levels of androgens, which stimulate sebaceous glands to proliferate and secrete large amounts of oil secreted by sebaceous glands and abnormal keratinization of follicular openings, resulting in the blockage of follicular pores with oil, which is manifested in a variety of lesions, such as acne, pimples, pustules, and nodules, and is accompanied by symptoms such as a feeling of pressure and pain. 2. Folliculitis: folliculitis is a kind of inflammatory reaction that occurs in the hair follicle, can be caused by not paying attention to cleanliness and hygiene, resulting in bacterial or fungal infection, its lesions manifested as pimples, pustules, and accompanied by redness, swelling, heat and pain and other inflammatory reactions, severe pus, ulceration, necrosis and so on, so the hair pimples can also be caused by folliculitis. Hair acne is recommended to consult a doctor in time, clear cause for targeted treatment, pay attention to personal hygiene in life, keep the scalp area clean and dry, avoid picking, scratching the affected area.