An anal fissure is a small tear or cut in the lining of the anus that causes severe pain and bleeding during bowel movements. Foods to avoid with an anal fissure include white flour, added sugars, processed foods, fried foods, unripe bananas, and dairy products. These foods are difficult to digest and can cause constipation, which exacerbates the symptoms of an anal fissure. It is recommended to see a colorectal doctor if anal fissure symptoms persist despite dietary changes.