Anal fissure


Anal fissure


An anal fissure is a tear or ulcer (open sore) that develops in the lining of the anal canal.

The anal canal is the last part of your large intestine, and is located between your rectum (a reservoir where stools are stored) and your anal orifice (the opening through which stools are passed out of the body).


Signs and symptoms

The most common symptoms of anal fissures are:

a sharp pain when you pass stools (faeces), 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

Visit your GP if you think you have an anal fissure.

Don't let embarrassment stop you seeking help. Anal fissures are a common problem that 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 ashaemorrhoids (swellings in or around the rectum and anus). They can also advise you about self-help measures and treatments that can help relieve your symptoms and reduce the risk of fissures recurring.


Diagnosing anal fissures

Your GP will first ask about your symptoms and the type of pain you have been experiencing. They may also ask about your toilet habits.

Your GP will 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) is not normally used to diagnose anal fissures, because it is likely to be painful.

Your GP may refer you to a specialist for 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. 

The measurement of a person's anal sphincter (the ring of muscles that open and close the anus) pressure is occasionally used for fissures that have not responded to simple treatments.


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 haveconstipation, 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 andulcerative colitis

pregnancy and childbirth 

occasionally, a sexually transmitted infection (STI), such assyphilis and herpes, which can infect and damage the anal canal

having unusually tight anal sphincter muscles (the muscles that surround the anal canal), which can increase the tension in your anal canal and make it more susceptible to tearing

In many cases, no clear cause can be identified.


Who is affected

Anal fissures are relatively common, with an estimated 1 in every 10 people affected at some point in their life.

Anal fissures affect both sexes equally and occur in people of all ages, including very young children. However, most cases occur in children and young adults between the ages of 10 and 30.


Treating and preventing anal fissures

Anal fissures usually heal within a few weeks without the need for medical treatment, although they can easily recur if they are caused by constipation and this remains untreated. In some people, symptoms from anal fissures last six weeks or more (chronic anal fissures).

It can be helpful to adopt some simple self-help measures to help make it easier to pass stools, which can allow existing fissures to heal and reduce your chances of developing fissures in the future. These measures include:

making sure you have plenty of fibre in your diet

staying well hydrated by drinking plenty of fluids

not ignoring the urge to pass stools

exercising regularly

Your GP can also prescribe medication to help relieve your symptoms and help 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.

In persistent cases where self-help measures and medication have not helped, surgery may be recommended. Surgery is often very effective in treating anal fissures, but it does carry a small risk of complications, such as temporary or permanent loss of bowel control.


Digestive health

Find out how to beat common digestive problems like bloating and indigestion

Treating anal fissures 

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

However, your GP can offer 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 recur easily, particularly if you don't follow the self-help advice outlined below.


Self-help advice

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 eating plenty of high-fibre foods, such as fruit, vegetables and wholegrain foods.

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, avoid 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.



There are a number of different medications 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 pass stools more easily.

Adults with an anal fissure will usually be prescribed bulk-forming laxative tablets or granules. Bulk-forming laxatives work by helping your stools to retain fluid, making them 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 pass stools.

Your GP may recommend starting treatment at a low dose and gradually increasing it every few days until you are able to pass soft stools every one or two days.



If you experience prolonged, burning pain after passing stools, your doctor may recommend taking common, over-the-counter painkillers, such as paracetamol or ibuprofen.

If you decide to take these medications, 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 two, your GP may prescribe a medication called glyceryl trinitrate (GTN). This comes in the form of an ointment, which should be applied directly to the anal area, usually twice a day.

GTN works by expanding blood vessels in and around the anus, which helps to increase the blood supply to the fissure. This increase in blood supply should help the fissure heal more quickly.

GTN can also help reduce the pressure in your anal canal, which should help ease the pain. The vast majority of acute fissures (which have been present for less than six weeks) will heal with GTN treatment, and around 7 in every 10 chronic fissures heal with GTN therapy, if it is used effectively.

Headaches are a very common side effect of this type of GTN ointment, affecting up to half of people using it. Some people may also feel dizzy or light-headed after using GTN. It is not suitable for children and should be used with caution in women who are pregnant or breastfeeding.

If headaches are a problem, it can help to reduce the ointment dosage for a few days. Using only a pea-sized amount of ointment five or six times a day is often better than using a larger amount twice a day. You should also make sure you are applying the ointment to the skin around the anus and not pushing it inside the anal canal. 

You will usually have to use GTN ointment for up to eight weeks, or until your fissure has completely healed.


Topical anaesthetics

If your pain is particularly severe, your GP may prescribe a topical anaesthetic to numb your anus before passing stools. A topical medicine is one that you apply directly to the affected area.

Topical anaesthetics do not help fissures to heal, but they 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 one to two weeks because the fissure should start to heal within this time.


Calcium channel blockers

Calcium channel blockers, such as diltiazem, are a type of medication 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 where the fissure is.

Side effects of topical calcium channel blockers can include headaches, dizziness and itchiness or burning at the site when you apply the medication. However, any side effects should pass within a few days, once your body gets used to the medication.

Topical calcium channel blockers are considered to be about as effective as GTN ointment in treating anal fissures, and they may be recommended if the medications above have not helped.

As with GTN ointment, you will usually have to use calcium channel blockers for up to eight 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 medications have not helped.

Botulinum toxin is a powerful poison that is 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 (contracting), helping to 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 are helpful for over 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 two to three months, which should normally allow enough time for the fissure to heal.



Your GP may arrange for you to have a follow-up appointment a few weeks after the start of your treatment. This will enable them to check that 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 does not respond to treatment after eight 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 will usually involve having some type of surgery.



If the treatments and measures above are ineffective, surgery may be recommended. Surgery 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 carries 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 sphincter muscle (the ring of muscle surrounding the anal canal) 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.

A lateral sphincterotomy is a short and relatively straightforward operation that is usually carried out under a general anaesthetic on a day patient basis. This means you will be asleep while the procedure is carried out, but you will not normally have to spend the night in hospital.

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

Less than 1 in every 20 people who have this type of surgery will experience some 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 themselves from passing wind.

The incontinence usually gets better, although in rare cases it can be permanent.


Advancement anal flaps

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

This procedure can be recommended to treat cases of long-term (chronic) anal fissures, which have occurred due to pregnancy or an injury to the anal canal.


Preventing anal fissures 

It is not always possible to prevent anal fissures, but you can reduce your risk by taking steps to avoid becoming constipated.

Some of the best ways to prevent constipation are outlined below.



It's important to ensure you have enough fibre in your diet. Adults should aim to eat at least 18g of fibre a day.

You can increase your fibre intake by eating more:



wholegrain rice

wholewheat pasta

wholemeal bread



You can usually see how much fibre a food item contains by checking the nutritional information on the back of the packet.

Eating more fibre will keep your bowel movements regular, because it helps food pass through your digestive system more easily. Foods high in fibre also make you feel fuller for longer.

If you are increasing your fibre intake, it's best to increase it gradually, because a sudden increase may make you feel bloated. You may also experience increased flatulence (wind) and have stomach cramps.



Make sure you drink plenty of fluids to avoid dehydration, and steadily increase your intake when you are exercising or when it is hot.

Try to cut back on the amount of caffeine, alcohol and fizzy drinks you consume.


Toilet habits

Never ignore the urge to go to the toilet, as this can cause your stools to dry and out and become harder to pass.

When you use the toilet, make sure you have enough time and privacy to pass stools comfortably.



Keeping mobile and active can also help reduce your risk of getting constipation. You should aim to do at least 150 minutes of physical activity every week.

Not only will regular exercise reduce your risk of becoming constipated, but it will also leave you feeling healthier and improve your mood, energy levels and general fitness.

Anal fissure