An anal fissure is a small tear or ulcer in the lining of the anal canal that causes pain during bowel movements. It is often caused by constipation or hard stools that stretch the anal canal. The most common symptoms are a sharp pain during bowel movements and bleeding. Treatment focuses on softening stools, applying topical medications, and relaxing the anal sphincter muscle. Surgery is an option for chronic cases that do not improve. Lifestyle changes like a high fiber diet, drinking water, and warm baths can help prevent recurrence.