An anal fissure is a tear or open sore (ulcer) that develops in the lining of the large intestine, near the anus.

Anal fissure symptoms

The most common symptoms of anal fissures are:

  • a sharp pain when you poo, often followed by a deep burning pain that may last several hours
  • bleeding when you poo – most people notice a small amount of bright red blood either in their poo or on the toilet paper

When to see a GP

See a GP if you think you have an anal fissure.

Do not 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 a GP will want to rule out other conditions with similar symptoms, such as piles (haemorrhoids).

They can also tell you about self-help measures and treatments that can relieve your symptoms and reduce the risk of fissures coming back.

Diagnosing anal fissures

A GP will ask you about your symptoms and the type of pain you have 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 a GP inserts a lubricated, gloved finger into your bottom to feel for abnormalities, is not usually used to diagnose anal fissures as it's likely to be painful.

The 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 bottom carried out using anaesthetic to minimise pain.

Occasionally, a measurement of anal sphincter pressure may be taken for fissures that have not 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, the last part of the large intestine.

Most cases occur in people who have constipation, when a particularly hard or large poo 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.

Treatment for anal fissure from a GP

A GP can prescribe medication to help relieve your symptoms and speed up the healing process.

This can include laxatives to help you poo more easily and painkilling ointment that you put directly on your anus.

Surgery may be recommended in persistent cases of anal fissure where self-help measures and medicine have not 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).

Anal fissures usually heal within a few weeks without the need for treatment.

But they can easily come back if they're caused by constipation that remains untreated.

In some people, symptoms from anal fissures last 6 weeks or more (chronic anal fissures).

How to ease symptoms of anal fissure

Adopting some simple self-help measures can make going to the toilet 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 30g of fibre a day
  • staying well hydrated by drinking plenty of fluids
  • not ignoring the urge to poo – this can cause your poo to dry out and become harder to pass
  • exercising regularly – you should aim to do at least 150 minutes of physical activity every week

You can help soothe the pain by taking simple painkillers, such as paracetamol or ibuprofen, or by soaking your bottom in a warm bath several times a day, particularly after a bowel movement.

Who's affected

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.

But children and young adults between 10 and 30 years of age are more likely to get anal fissures.


Like other small cuts or tears to the skin, an anal fissure will often heal by itself within a few weeks.

However, you should see your GP if you have an anal fissure as they can give you advice and medications to help ease your symptoms and allow the fissure to heal more quickly.

Most anal fissures will heal with treatment, although they can happen again easily, particularly if you don't follow the self-help advice outlined below.


There are a number of self-help measures your GP may recommend to relieve constipation and reduce the pain caused by anal fissures. 

Relieving constipation can allow anal fissures to heal and reduce the chances of further fissures developing in the future.

Self-help measures include:

  • increasing your daily intake of fibre by including plenty of high-fibre foods in your diet, such as fruit, vegetables and wholegrains
  • avoiding dehydration by drinking plenty of water
  • trying to get more exercise – for example, by going for a daily walk or run
  • working out a place and time of day when you can comfortably spend time on the toilet
  • not delaying going to the toilet when you feel the urge
  • if you use wet wipes, avoiding products that contain fragrance or alcohol as this could lead to discomfort or itching – if you use toilet paper, use a soft brand and avoid wiping too hard
  • soaking your bottom in a warm bath several times a day, particularly after a bowel movement, to relax the muscles in your anus


There are a number of different medicines your GP may recommend to help reduce your symptoms and allow your anal fissure to heal.


Laxatives are a type of medicine that can help you poo more easily.

Adults with an anal fissure will usually be prescribed bulk-forming laxative tablets or granules. These work by helping your poo retain fluid, making it softer and less likely to dry out.

Children with an anal fissure are usually prescribed an osmotic laxative oral solution. This type of laxative works by increasing the amount of fluid in the bowels, which stimulates the body to need to poo.

Your GP may recommend starting treatment at a low dose and gradually increasing it every few days until you're able to pass soft poo every 1 or 2 days.


If you experience prolonged burning pain after passing stools, your doctor may recommend taking common painkillers, such as paracetamol or ibuprofen which you can buy from a pharmacy or supermarket.

If you decide to take these medicines, make sure you follow the dosage instructions on the patient information leaflet or packet.

Glyceryl trinitrate

If your symptoms don't improve within a week or 2, your GP may prescribe a medicine called glyceryl trinitrate (GTN), an ointment applied to the anal canal, usually twice a day.

GTN works by expanding blood vessels in and around the anus, increasing the blood supply to the fissure and helping it heal faster. It can also help reduce the pressure in the anal canal, which should ease the pain.

You'll usually have to use GTN ointment for at least 6 weeks, or until your fissure has completely healed.

The majority of acute fissures (present for less than 6 weeks) will heal with GTN treatment. Around 7 in every 10 chronic fissures heal with GTN therapy if used correctly.

Headaches are a very common side effect of GTN ointment, affecting up to half of people who use it. Some people also feel dizzy or lightheaded after using the ointment.

GTN isn't suitable for children and should be used with caution in pregnant or breastfeeding women.

If headaches are a problem, reducing the amount of ointment you use for a few days can help. Using a pea-sized amount of ointment 5 or 6 times a day is often better than using a larger amount twice a day.

Topical anaesthetics

If you have particularly severe anal pain, your GP may prescribe a topical anaesthetic to numb your anus before passing stools.

A topical medicine is one you rub directly into the affected area. It won't help fissures heal, but it can help ease the pain.

Lidocaine is the most commonly prescribed topical anaesthetic for anal fissures. It comes in the form of either a gel or an ointment, and is usually only used for 1 to 2 weeks because the fissure should start to heal within this time.

Calcium channel blockers

Calcium channel blockers, such as diltiazem, are a type of medicine usually used to treat high blood pressure (hypertension).

However, topical calcium channel blockers that are applied directly to the anus have also proved useful in treating some people with anal fissures.

Topical calcium channel blockers work by relaxing the sphincter muscle and increasing blood supply to the fissure.

Side effects can include headaches, dizziness, and itchiness or burning at the site when you use the medicine. Any side effects should pass within a few days once your body gets used to the medicine.

Topical calcium channel blockers are thought to be about as effective as GTN ointment for treating anal fissures, and may be recommended if other medicines haven't helped.

As with GTN ointment, you'll usually have to use calcium channel blockers for at least 6 weeks, or until your fissure has completely healed.

Botulinum toxin injections

Botulinum toxin is a relatively new treatment for anal fissures. It's usually used if other medicines haven't helped. Botulinum toxin is a powerful poison that's safe to use in small doses.

If you have an anal fissure, an injection of the toxin can be used to paralyse your sphincter muscle. This should prevent the muscle from spasming, helping reduce pain and allowing the fissure to heal.

It's not clear exactly how effective botulinum toxin injections are for anal fissures, but research suggests they're helpful for more than half the people who have them. This is similar to having treatment with GTN ointment and topical calcium channel blockers.

The effects of botulinum toxin injections last for around 2 to 3 months, which should normally allow enough time for the fissure to heal.


You may have a follow-up appointment a few weeks after starting your treatment. This will allow your GP to check your fissure has healed or is showing adequate signs of improvement.

If the fissure has completely healed, your GP may recommend a further follow-up appointment a few weeks later.

If your anal fissure is particularly severe or doesn't respond to treatment after 8 weeks, you may have to be referred to a colorectal surgeon, a doctor who specialises in conditions that affect the rectum and anus, for specialist treatment. This usually involves having some type of surgery.


Surgery may be recommended if other treatments haven't worked. 

It is generally considered to be the most effective treatment for anal fissures, with more than 90% of people experiencing good long-term results. However, it does carry a small risk of complications.

There are a number of different surgical techniques that can be used to treat anal fissures. The main techniques used are outlined below.

Lateral sphincterotomy

A lateral sphincterotomy involves making a small cut in the ring of muscle surrounding the anal canal (sphincter) to help reduce the tension in your anal canal. This allows the anal fissure to heal and reduces your chances of developing any more fissures.

It is a short and relatively straightforward operation that's usually carried out under a general anaesthetic on a day patient basis. This means you'll be asleep while the procedure is carried out, but you won't usually have to spend the night in hospital.

A lateral sphincterotomy is 1 of the most effective treatments for anal fissures, with a good track record of success. Most people will fully heal within 2 to 4 weeks.

Less than 1 in 20 people who have this type of surgery will experience some temporary loss of bowel control (bowel incontinence) afterwards as a result of damage to the anal muscles.

However, this is usually a mild type of incontinence where the person is unable to prevent passing wind, and usually only lasts a few weeks.

Advancement anal flaps

Advancement anal flaps involve taking healthy tissue from another part of your body and using it to repair the fissure and improving the blood supply to the site of the fissure.

This procedure may be recommended to treat long-term (chronic) anal fissures caused by pregnancy or an injury to the anal canal.

The information on this page has been adapted by NHS Wales from original content supplied by NHS UK NHS website nhs.uk
Last Updated: 01/07/2021 14:58:08