An anal fissure is a tear or open sore (ulcer) that develops in the lining of the anal canal.
The anal canal is the last part of the large intestine. It's located between the rectum – where stools are stored – and the opening in the bottom stools are passed through (anus).
Anal fissure symptoms
The most common symptoms of anal fissures are:
- a sharp pain when you pass stools, often followed by a deep burning pain that may last several hours
- bleeding when you pass stools – most people notice a small amount of bright red blood either in their stools or on the toilet paper
When to see your GP
See your GP if you think you have an anal fissure. Don't let embarrassment stop you seeking help: anal fissures are a common problem GPs are used to dealing with.
Most anal fissures get better without treatment, but your GP will want to rule out other conditions with similar symptoms, such as piles (haemorrhoids) ↗.
Your GP can also tell you about self-help measures and treatments that can relieve your symptoms and reduce the risk of fissures recurring.
Diagnosing anal fissures
Your GP will ask you about your symptoms and the type of pain you've been experiencing. They may also ask about your toilet habits. They'll usually be able to see the fissure by gently parting your buttocks.
A digital rectal examination ↗ – where your GP inserts a lubricated, gloved finger into your anus to feel for abnormalities – isn't usually used to diagnose anal fissures as it's likely to be painful.
Your GP may refer you for specialist assessment if they think something serious may be causing your fissure.
This may include a more thorough examination of your anus carried out using anaesthetic ↗ to minimise pain.
Occasionally, a measurement of anal sphincter pressure may be taken for fissures that haven't responded to simple treatments. The anal sphincter is the ring of muscles that open and close the anus.
What causes anal fissures?
Anal fissures are most commonly caused by damage to the lining of the anus or anal canal.
Most cases occur in people who have constipation ↗, when a particularly hard or large stool tears the lining of the anal canal.
Other possible causes of anal fissures include:
- persistent diarrhoea ↗
- inflammatory bowel disease (IBD) ↗, such as Crohn's disease ↗ and ulcerative colitis ↗
- pregnancy and childbirth
- occasionally, a sexually transmitted infection (STI) ↗, such as syphilis ↗ or herpes ↗, which can infect and damage the anal canal
- having unusually tight anal sphincter muscles, which can increase the tension in your anal canal, making it more susceptible to tearing
In many cases, no clear cause can be identified.
Treating and preventing anal fissures
Anal fissures usually heal within a few weeks without the need for treatment. However, they can easily recur if they're caused by constipation that remains untreated.
In some people, symptoms from anal fissures last six weeks or more (chronic anal fissures).
Adopting some simple self-help measures can make passing stools easier. This will allow existing fissures to heal, as well as reduce your chances of developing new fissures in the future.
Self-help measures for avoiding constipation include:
- plenty of fibre ↗ in your diet, such as fruit and vegetables ↗ and wholemeal bread, pasta and rice – adults should aim to eat at least 18g of fibre a day
- staying well hydrated by drinking plenty of fluids ↗
- not ignoring the urge to pass stools – this can cause your stools to dry out and become harder to pass
- exercising regularly ↗ – you should aim to do at least 150 minutes of physical activity every week
Your GP can also prescribe medication to help relieve your symptoms and speed up the healing process.
This can include laxatives ↗ to help you pass stools more easily and painkilling ointment that you apply directly to your anus.
Surgery may be recommended in persistent cases of anal fissure where self-help measures and medication haven't helped.
Surgery is often very effective at treating anal fissures, but it does carry a small risk of complications, such as temporary or permanent loss of bowel control (bowel incontinence) ↗.
Read more about treating anal fissures ↗.
Anal fissures are quite common, with around 1 in every 10 people affected at some point in their life.
They affect both sexes equally and people of all ages can get them. However, children and young adults between 10 and 30 years of age are more likely to get anal fissures.