Sweating and moistness at the anal opening may be caused by anal incontinence, anorectal lesions, perianal skin lesions and other causes. 1. Anal incontinence: generally common in anal sphincter hypofunction or injury, such as postoperative local muscle injury after anal fistula and perianal abscess, which can lead to anal incontinence and inability to control bowel movement. Especially when the stool is thin, it may flow out on its own, which will stimulate the patient to have the symptom of sweating and moisture at the anal opening. 2. Anorectal lesions: mainly hemorrhoids, anal fistula, anal sinusitis, anal fissure and other diseases, these diseases may drain the contents of the intestines and anal canal to the perianal area, leading to sweating and wetness at the anal opening. 3. Perianal skin lesions: usually perianal eczema, anal lichen planus and other diseases may also lead to moisture sweating at the anal opening. It is recommended that patients who have the phenomenon of moist sweating at the anus, actively seek medical treatment, and under the guidance of the doctor to carry out the relevant examination and treatment.