An anal fissure is a small tear or split in the delicate lining of the anal canal. It’s very common and can affect anyone, though it’s often linked to constipation or a period of hard or difficult bowel motions. Fissures typically cause a sharp, tearing pain when passing a stool, sometimes followed by a deeper ache that can last for hours, along with bright red bleeding on the paper or in the bowl. Most fissures settle with simple measures, but ongoing pain or bleeding should always be assessed to confirm the diagnosis and start the right treatment.
What Causes Anal Fissures?
Constipation or straining
Passing a hard or large stool is the most common trigger.
Chronic diarrhoea
Repeated loose motions can also irritate and tear the lining.
Childbirth
Fissures can develop during or after vaginal delivery.
Reduced blood flow to the area
Makes healing slower once a tear occurs.
Underlying bowel conditions
Occasionally linked to Crohn's disease or other inflammatory conditions.
Not an infection
Fissures are not contagious and are not a sexually transmitted infection.
When to Seek Assessment Promptly
- Sharp pain when opening your bowels that doesn’t settle
- Bright red bleeding with bowel motions
- A tear or ulcer you can see or feel around the anus
- Pain that has become persistent, or a fissure that keeps recurring
- Any change in bowel habit alongside the pain or bleeding
- Uncertainty about what’s causing the symptoms
How it is treated
Most anal fissures heal with simple measures: a high fibre diet, plenty of fluids, and a stool softener to keep motions soft and comfortable, alongside good hygiene and pain relief. A topical ointment, such as GTN or diltiazem, is often prescribed to relax the muscle around the anus and improve blood flow, helping the tear heal. Where a fissure becomes chronic or doesn’t respond to these measures, further options include a Botox injection to relax the muscle, or, in persistent cases, a small surgical procedure to help the area heal. Mr Kimble will explain which option is most appropriate for your fissure and talk you through what to expect at each stage.
Most fissures are uncomfortable rather than dangerous, but see a doctor promptly if you notice heavy bleeding, worsening pain, a fever, or a lump or swelling around the anus, so the cause can be properly assessed.