The redness and swelling of the edge of the subcoronal sulcus may be urinary system infection, prepuce glans, annular lichen planus, prepuce incarceration, etc., and should be promptly consulted to find out the cause of the disease. 1. Urinary system infection: if the patient has a urinary system infection, there may be redness and swelling at the coronal groove of the glans. 2. circumcision: usually due to the long foreskin, poor local hygiene, or unclean sex and other factors, often manifested in the glans coronal groove of the circle of redness, pimples, itching, vesicles, ulcers and so on. 3. Circumscribed lichen planus: usually due to the body’s immunity decline, resulting in pathogenic bacteria infection, often manifested in the glans coronal groove area, there is a ring of moss-like lesions, and there is a ring of redness and swelling of the glans coronal groove. 4. foreskin inlay: usually due to sexual intercourse or masturbation, resulting in the foreskin turned up, and did not reset it in time, resulting in foreskin inlay and other factors, often manifested in the glans coronal groove of a circle of redness and swelling, and the distal foreskin and the head of the penis, there is a certain amount of swelling, pain. In summary, patients should pay attention to local cleanliness, and wash with warm boiled water every day. Avoid coitus during treatment, so as not to cause cross-infection. It is recommended that patients consult a doctor in time, ask the doctor to clarify the cause of the disease and give targeted treatment.