Acne vulgaris is medically known as acne vulgaris, and its causes include endocrine factors, abnormal keratinization of sebaceous gland ducts in hair follicles, bacterial infections, and so on. 1. Endocrine factors: If the level of androgen in the body increases, it may lead to a large amount of sebum secretion, thus triggering acne vulgaris. 2. Abnormal keratinization of follicular sebaceous gland ducts: This may lead to blockage of the follicular ducts, which prevents the normal discharge of shed cells and sebum, thus leading to localized acne vulgaris. 3. Bacterial infection: Proliferation and infection of bacteria such as Propionibacterium acnes may lead to localized inflammation, thus causing acne vulgaris. There are many causes of acne vulgaris, so it is recommended that patients consult a doctor at a regular hospital and follow the doctor’s instructions.