An anal fistula is an abnormal tunnel that forms between the inside of the anal canal and the skin near the anus, usually after infection or an abscess in that area. People commonly notice pain, swelling, pus discharge, bad smell, irritation, or repeated boils near the anus. Symptoms may improve temporarily, then return, because the tract remains under the skin. Treatment usually depends on the size, depth, infection, and exact path of the fistula. Medicines and antibiotics may help reduce infection or pain for a short time, but they usually do not completely resolve the fistula. Many fistulas eventually require procedures such as fistulotomy, laser treatment, seton placement, or other surgical methods to close the tract and prevent recurrence. Sitz baths, keeping the area clean, and avoiding constipation may help reduce discomfort during treatment. Persistent pus discharge, fever, severe swelling, difficulty passing stool, or increasing pain can indicate active infection and may require prompt surgical assessment to prevent deeper complications.