Why does my bottom hurt when I poop?

Possible causes of pain in the anus during bowel movements include: 1. Constipation: Long-term constipation leads to dry, hard stools that can irritate the anal mucosa during defecation, causing pain. 2. Hemorrhoids: Especially thrombosed external hemorrhoids, where the protruding hemorrhoidal mass is rubbed or compressed by stool passing through the anus during defecation, resulting in pain. 3. Anal fissure: A tear in the skin lining of the anal canal, which causes severe pain when stool passes over the wound, possibly accompanied by bleeding, redness, swelling, and itching. 4. Perianal abscess: A subcutaneous mass around the anus causes a feeling of distension and pain, which worsens during bowel movements. 5. Poor dietary habits: Regular consumption of spicy or irritating foods can stimulate the intestinal mucosa and may also lead to anal pain during defecation.