Forehead and chin acne is mostly considered to be caused by acne vulgaris, the cause of which is not yet clear, and may be related to abnormal hormone levels, excessive sebum secretion, propagation of Propionibacterium acnes, and excessive keratinization of the follicular epithelium, among other factors. 1. Abnormal hormone levels: An abnormal increase in androgens in the body will stimulate the sebaceous glands to over-secrete oil, which will lead to the occurrence of acne. 2. Excessive secretion of sebaceous glands: This is especially seen in bad lifestyle habits, such as staying up late and consuming foods high in sugar and oil, which will stimulate the sebaceous glands to increase secretion, thus triggering acne vulgaris. 3. Propionibacterium acnes reproduction: Propionibacterium acnes can activate keratinocytes and hydrolyze triglyceride lipids in sebum to free fatty acids, which can stimulate inflammation of hair follicles, resulting in localized pimples, nodules, pustules and other symptoms. 4. Follicular epithelial hyperkeratosis: when the follicular epithelium is hyperkeratotic, it is easy to block the mouth of the hair follicle, resulting in poor excretion of oil, retention in the hair follicle, thus triggering acne. 5. Others: Improper facial cleansing, which can easily lead to cosmetics and other residues on the skin surface, can also induce acne. Patients with acne on the forehead and chin can go to a regular hospital to identify the cause and take relevant treatment measures, taking into account their own situation.