Red and itchy anus may be caused by perianal eczema, hemorrhoids, anal fistula and other diseases. 1. Perianal eczema: perianal eczema can be manifested as red, itchy anus, perianal skin can appear erythema, blisters, mossy changes and flaking and other changes, blisters and pustules rupture, plasma or pus can flow out, causing anal moisture discomfort and itching. 2. Hemorrhoids: hemorrhoids can also appear anal redness and itching, hemorrhoids can appear perianal prolapse, prolapsed hemorrhoids can be red, in addition to the increase in perianal secretions, can cause anal discomfort, moist unclean, accompanied by itching. 3. Anal fistula: anal fistula is caused by perirectal anal canal abscess, patients with perianal redness, accompanied by purulent secretions, under the stimulation of secretions, there can be anal itching. In addition to the above diseases, other diseases can also lead to anal redness and itching, please consult a doctor in a timely manner and ask the doctor to be disposed of.