Perianal dampness is caused by increased discharge from the anal opening and has many causes, which can be physiological or pathological. To sum up, there are five causes as follows. One is that the sebaceous glands and sweat glands in the anal department secrete a lot, and the anus is deep between the two sides of the buttocks. This deep position is very unfavorable to the evaporation of sweat around the anus, especially for people with an obese body type, and the position of the anus is deeper, causing dampness around the anus. There are also some people who do not pay attention to hygiene around the anus, which can also cause symptoms of increased secretions in the anal department. Second, the anal sphincter muscle of the elderly or frail people is relaxed and weak, resulting in poor anal closure and the overflow of intestinal and anal fluids outside the anus, producing symptoms of increased secretions. Third, severe anal fissures and anal fistulas with external orifices near the anus have moist symptoms due to much inflammatory exudation that overflows out of the anus. Fourth, complete rectal prolapse of degree III often occurs when the anal sphincter is weak and the whole rectum or mucosa prolapses outside the anus when walking or exerting oneself, and the fluid on the surface of the rectal mucosa will contaminate the skin around the anus, resulting in the symptoms of large amount of secretion from the anal opening. Fifth, anal eczema, herpes and anal contact dermatitis are also factors that cause increased local discharge from the anus. If there are symptoms of dampness and scratching around the anus, you should go to the hospital promptly.