Dampness in the buttock crack is generally not AIDS, but may be due to the high secretion of sweat glands in the buttock groove and anal eczema. If the underwear is usually too tight, the buttock groove sweat glands secrete a lot, and the air circulation is not good, and the sweat does not evaporate easily after activities, which can lead to dampness in this area. In addition, anal eczema can also easily cause the symptoms of dampness in the buttock sulcus, i.e. skin infiltration and hypertrophy, often accompanied by itching, can occur chaps, generally through the use of anti-itch drugs, avoid external stimulation and other methods can be alleviated. In contrast, AIDS mainly manifests itself as persistent fever, night sweats, prolonged cough, headache and dizziness, diarrhea, blood in stool and persistent widespread generalized lymph node swelling, etc. A simple moist buttock crevice cannot be judged as AIDS. If the patient has had high-risk sexual behavior, it is recommended to be promptly admitted to the hospital for screening. Patients who sweat a lot are advised to take a shower in time to keep the buttock cleavage clean and dry. It is recommended to change underwear regularly, choose loose cotton clothing, and go to the anorectal department for medical treatment if there is any discomfort.