Anal fissure

An anal fissure is a small tear or crack in the lining of the anus. It's a common cause of pain and bleeding during and after passing stools. Most anal fissures heal on their own within a few weeks with simple measures; some become chronic and need more active treatment.

Causes

• Passing hard or large stools — the most common trigger
• Chronic constipation or prolonged diarrhoea
• Childbirth
• Anal intercourse
• Conditions affecting the lower digestive tract — Crohn's disease, ulcerative colitis, tuberculosis, HIV, anal cancer (rare)

Symptoms

• Sharp, tearing pain during bowel movements
• Pain that can persist for minutes to hours after passing stools
• Bright red blood on the stool or on the toilet paper (small amounts)
• A visible small tear or "skin tag" near the anus
• Itching or irritation
• Sometimes, avoiding bowel movements out of fear of pain — which makes constipation and the fissure worse

Home care and first-line treatment

Most acute fissures heal with simple measures:

• High-fibre diet — plenty of vegetables, fruits, pulses, whole grains. Aim for 25-30g fibre a day.
• Adequate fluids — plenty of water
• Sitz baths — sit in warm water for 10-15 minutes, 2-3 times a day, especially after bowel movements. Very soothing and helps healing.
• Stool softeners or laxatives — ispaghula husk (isabgol), lactulose, polyethylene glycol. Avoid straining.
• Topical anaesthetic cream — for short-term relief
• Don't hold in bowel movements — goes to the toilet when you need to, to avoid hardening

If it doesn't heal

Chronic fissures (not healed after 6-8 weeks) may need additional treatment:

• Topical nitroglycerin-based ointment — relaxes the anal sphincter and improves blood flow to help healing. Can cause headaches.
• Topical calcium-channel-blocker creams — fewer side effects than nitroglycerin
• Botulinum toxin injection — temporarily relaxes the sphincter; similar effectiveness to GTN
• Surgery — lateral internal sphincterotomy — a small cut in the sphincter to reduce spasm and allow healing. High success rate, but small risk of incontinence.

See a doctor if pain is severe, bleeding is significant or persistent, the fissure doesn't heal after 6-8 weeks of home care, or there are other concerning symptoms (weight loss, change in bowel habit). Fissures with unusual features or on the side rather than the back may need investigation for underlying causes (Crohn's, TB, infection).