Pimples under the lips may be a symptom of acne, folliculitis or herpes simplex, and you need to go to the hospital for diagnosis to clarify the cause. 1. Acne is related to high androgen levels in the body, and is easily triggered by staying up late for a long time, loving spicy and stimulating foods, and drinking alcohol. It is easy to appear on the forehead, cheeks and around the mouth. Manifestation of scattered red bumps on the skin, some of the bumps have pus tip, bumps have different degrees of itching or pain, often with the symptoms of facial oil. 2. Folliculitis is caused by bacterial infection of the skin such as Staphylococcus aureus, and patients with poor immune function or diabetes are prone to it. The manifestation of a single red pimple around the lips, pimple soybean to peanut size, the surface of the pus head, often accompanied by pain. 3. Herpes simplex is caused by viral infections and is prone to attacks when the immune system is low. It is characterized by red spots under the lips with dense blisters, accompanied by varying degrees of itching, burning and pain. There may be other causes of acne under the lips, it is recommended to go to the hospital in time, clear diagnosis, symptomatic treatment.