Red anus is considered to be related to perianal inflammation, perianal eczema, anal fissure, perianal abscess and so on. 1. Perianal inflammation: perianal inflammation is related to infection, diarrhea, improper diet, etc., patients will appear around the anus, red, swollen, hot, painful, and accompanied by inflammatory secretions, perianal itching and other discomfort symptoms, which can be manifested as red anus. 2. Perianal eczema: the cause is not clear, may be related to trauma, clothing friction, perianal secretion stimulation. Patients will appear local skin itching, erythema, blisters, moss-like changes, flaking, anal moisture and other symptoms, but also can be manifested as anal red. 3. Anal fissure: anal fissure can cause anal redness in some patients. Long-term constipation and diarrhea, anal canal stenosis, poor local blood supply can be caused by anal fissure, the patient’s main manifestations are perianal pain, blood in the stool, perianal skin itching. 4. Perianal abscess: Perianal abscess can also cause red anus in some patients, accompanied by perianal swelling, pain and fidgeting, loss of appetite and other symptoms. Perianal abscess is related to anal crypt infection, trauma and Crohn’s disease. It is recommended that people with red anus and other symptoms of discomfort should consult a doctor for timely examination, and take medication as prescribed by the doctor after clarifying the disease, so as to improve the abnormal situation as soon as possible and avoid aggravation of the condition.