Erythromycin ointment can be used on the wound after anal fistula surgery. Erythromycin ointment has an anti-inflammatory effect because the wound is inflamed after anal fistula surgery, and the anti-inflammatory effect can promote wound healing. Erythromycin ointment also has a lubricating effect, which can promote defecation after anal fistula surgery and reduce the pain of the wound caused by defecation after anal fistula surgery. In addition to erythromycin ointment for post-operative anal fistula wounds, a small piece of petroleum jelly gauze can also be placed on the post-operative wounds of anal fistula to protect them, reduce pain in the wounds during defecation, and prevent pseudo-healing after anal fistula surgery. So by using erythromycin ointment and Vaseline gauze you can reduce the pain of defecation after anal fistula surgery, prevent recurrence and promote wound healing.