Pain in the back passage is common, and most causes are not serious. The type of pain gives a good clue to the cause.
Common causes
- Anal fissure: a small tear in the skin of the anus, often after passing a hard stool. It causes sharp pain during and after a bowel movement, sometimes lasting an hour or more, and a little bright red blood on the tissue paper.
- Clotted (thrombosed) external pile: a sudden, painful, bluish lump at the edge of the anus. The pain is worst in the first few days and then settles. See haemorrhoids.
- Abscess: a collection of pus near the anus. The pain is constant and throbbing, gets worse over days, and there may be swelling and fever. It needs drainage, usually by a surgeon, so see a doctor promptly.
- Muscle spasm: brief, sudden cramps in the back passage, often at night, that pass on their own within minutes. They are harmless.
- Less common causes include an anal fistula, inflammation from Crohn’s disease, and rarely, cancer.
Internal piles, inside the back passage, are usually painless. They bleed or prolapse rather than hurt.
What helps
- Keep stools soft: more fibre, enough water, and a fibre supplement or gentle laxative if needed (see constipation)
- Do not strain or sit on the toilet for long
- Sit in a few centimetres of warm water for 10 to 15 minutes, two or three times a day
- Simple painkillers, but avoid codeine-type painkillers, which cause constipation
Most fissures heal within a few weeks. A fissure that does not heal can be treated with an ointment that relaxes the muscle around the anus. If that fails, a colorectal surgeon can offer other treatment.
When to see a doctor
- Pain that is severe, getting worse, or not settling after a week
- A lump with fever, or pus
- Bleeding, especially if it is mixed with the stool, or with a change in bowel habit (see blood in the stool)
An examination of the back passage usually gives the answer. A colonoscopy may be advised if there is bleeding or other symptoms.
General information only. Reviewed by Dr Chia Chung King, 2026-11-13. Book a consultation.