There are many reasons for pain in the anus after a bowel movement: first, it could be an anal fissure, such as long-term dry stool that can easily damage the skin of the anal canal leading to fissures, when the abdominal pressure increases during a bowel movement, the dry stool can easily damage the trauma of the anal fissure and cause pain. The second, there may be mixed hemorrhoids, mixed hemorrhoids are varicose veins, it is divided into four stages, if it is three or four stages, the nucleus of the hemorrhoid easily prolapse out of the anus, sometimes prolapse longer, resulting in hemorrhoid vein stagnation, swelling, thus forming a thrombus. When defecating, the area around the anus is more painful. Third, if the anal gland is infected later, it spreads along the anal canal to the perianal skin to form a perianal abscess, which is usually particularly painful in the anus when defecating. The fourth, if you do not pay attention to diet, long-term alcohol consumption or diet stimulating food, such as chili peppers, can also lead to swelling of the hemorrhoid nucleus, thus causing pain around the anal spicy swelling. So there are many reasons for anal pain after a bowel movement, and you should promptly perform a rectal examination and, if necessary, anoscopy to clarify its cause.