Anal Fissure: Why It Hurts and How It's Treated

An anal fissure is a small tear in the lining of the anal canal. It's a common cause of anal pain and bleeding — and it can be surprisingly painful for something so small.

Why it hurts so much

The anal lining is very sensitive, and the surrounding muscle tends to go into spasm when there's a tear. That spasm both causes sharp pain — often described as passing glass during a bowel movement — and reduces blood flow to the area, which slows healing and keeps the cycle going.

Typical symptoms

Sharp pain during and after passing stool, often with a small amount of bright red blood, and sometimes a lingering ache.

How it's treated

Most fissures heal with measures that break the pain–spasm cycle:

• Softer stools through fibre, fluids and stool softeners, to reduce trauma.
• Ointments (such as those that relax the muscle and improve blood flow) to allow healing.
• Botulinum toxin injection to relax the muscle if ointments don't work.
• Surgery (a small procedure on the muscle) for fissures that won't heal, considered carefully because of its effect on continence.

When to see a specialist

If the pain is severe or a fissure won't settle after a few weeks of treatment, get assessed.

This article provides general information and is not a substitute for individual medical advice. Please consult a qualified clinician about your own circumstances.