The main causes of itching in the anus after defecation include anal fissures, anal eczema, hemorrhoids and other anal and rectal inflammatory diseases, and sometimes allergic reactions can also cause this symptom to occur. Firstly, anal fissures can cause itching in the anus after defecation, especially in people with long-term constipation, which can cause many fissures in the skin of the anus, and when defecating, feces can stimulate the fissures, thus causing itching. Secondly, the phenomenon of itching in the anal area after defecation is one of the symptoms of anal eczema. The imbalance of the body’s own endocrine secretion and the long-term moist environment are the main causes of anal eczema. Anal eczema can cause a large number of papules and breakouts on the skin of the anus, which can be easily stimulated by feces, resulting in itching after a bowel movement.