The main clinical symptoms of anal fistula mainly include pus discharge, pain, and itching, therefore it definitely causes pain. Usually, anal fistulas do not cause much pain, but when the external opening's drainage is obstructed, pus accumulation can lead to acute episodes, characterized by local swelling and pain, accompanied by significant tenderness. After the pus drains, the pain will decrease, indicating that anal fistulas do cause pain. Other main clinical manifestations of anal fistulas primarily involve pus discharge; that is, there is continuous secretion of small amounts of pus from the external fistula opening, which then causes local moisture around the anus, irritating the skin around the anus and leading to anal itching.