Pimples on the upper lip are usually referred to as acne, which is related to androgen-induced sebum secretion, propagation of Propionibacterium acnes, or keratinization of the follicular sebaceous gland ducts. 1. Androgen-induced sebum secretion: Follicular sebaceous glands, as independent endocrine tissues of the skin, are regulated by sex hormones. Increased androgen levels or imbalance between male and female hormone levels after puberty can cause sebaceous glands to enlarge and sebum secretion to increase. Increased androgen levels due to polycystic ovary syndrome may also cause acne on the side of the face. 2. Propionibacterium acnes: Sebum provides oil and an anaerobic environment for the growth of microorganisms such as Propionibacterium acnes in the hair follicles, which can multiply in the hair follicles, resulting in inflammation and the formation of acne. 3. Follicular sebaceous gland duct keratinization: when the follicle duct keratinocyte proliferation and hyperkeratosis, the latter makes sebum excretion blocked, when sebum, keratin plugs, etc. accumulate in the follicle mouth that is the formation of acne. Upper lip acne may also have other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, to give targeted treatment or treatment.