The causes of edema at the inner mouth of anal fistula include bacterial infection, blood circulation disorder, etc. The symptoms can be improved through general treatment and medication and surgery after the cause is clarified. 1. Bacterial infection: inflammation stimulation of the mucous membrane in the anal fistula will cause local mucosal edema, it is recommended to use antibiotics under the guidance of a doctor to fight infection, such as penicillin, doxycycline and other drugs to control inflammation and reduce edema, adverse reactions to timely medical care, drug allergy is prohibited. 2. blood circulation disorders: anal fistula internal mouth blood circulation disorders can also cause edema, can warm water sitz bath or 1:5000 potassium permanganate solution sitz bath, alleviate edema, promote the improvement of symptoms, serious cases are recommended to timely surgical treatment to improve blood circulation. In addition to general treatment, quitting smoking and drinking, eating a light diet, regular work and rest, and avoiding nervousness and anxiety can also promote symptomatic relief. The specific treatment measures should be in accordance with the doctor’s prescription.