Closed mouth is also known as whitehead acne. The causes of closed mouth on the face may include endocrine disorders, bad habits, abnormal peri-corneal keratinization and bacterial infections. 1. Endocrine disorders: If the patient has endocrine disorders such as excessive secretion of androgens, excessive secretion of androgens will stimulate the sebaceous glands, promote the development of sebaceous glands, so that sebaceous glands increase the secretion of sebum, which will increase the chances of the patient’s face closure greatly increased. 2. Bad habits: staying up late for a long time, high-calorie, high-fat diet, obesity, mental stress, improper facial cleansing, the use of poor-quality skin care products, cosmetics and other bad habits will make the patient’s facial sebaceous glands increase secretion of sebum, and in severe cases, even clog the facial pores, thus making the face of the occlusion increased. 3. Abnormal perifollicular keratinization: when the patient’s hair follicle sebaceous gland openings are over-keratinized, narrowed, blocked, and other perifollicular cellular opening keratinization abnormalities related to lesions, sebum secretion will be impeded, thus triggering the occurrence of closed mouth acne, so that the patient appeared on the face of the increased number of closed mouths. 4. Bacterial infection: the infection of hair follicles by bacteria such as Propionibacterium acnes, Malassezia, Staphylococcus aureus, etc., will cause localized inflammatory reaction of the hair follicles, sebaceous glands and other pathological changes, which will lead to the occurrence of closed-mouth acne, and so the face of closed-mouth acne may be caused by bacterial infection. To summarize, it is recommended that patients with a lot of closed mouth go to the hospital to clarify the cause of the disease and timely treatment to avoid further aggravation of the condition.