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 doctor
See your doctor if you think you have an anal fissure. Don't let embarrassment stop you seeking help: anal fissures are a common problem doctors are used to dealing with.
Most anal fissures get better without treatment, but your doctor will want to rule out other conditions with similar symptoms, such as piles (haemorrhoids) .
Your doctor 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 doctor 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 doctor 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 doctor 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
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.
Your doctor 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) .
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 doctor 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 recur easily, particularly if you don't follow the self-help advice outlined below.
There are a number of self-help measures your doctor 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
See preventing anal fissures for more self-help advice.
There are a number of different medications your doctor 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. These work by helping your stools 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 doctor may recommend starting treatment at a low dose and gradually increasing it every few days until you're 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.
If your symptoms don't improve within a week or two, your doctor may prescribe a medication 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 six weeks, or until your fissure has completely healed.
The majority of acute fissures (present for less than six 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 five or six times a day is often better than using a larger amount twice a day.
If you have particularly severe anal pain, your doctor may prescribe a topical anaesthetic to numb your anus before passing stools.
A topical medicine is one you apply directly to 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 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 the fissure.
Side effects can include headaches, dizziness, and itchiness or burning at the site when you apply the medication. Any side effects should pass within a few days once your body gets used to the medication.
Topical calcium channel blockers are thought to be about as effective as GTN ointment for treating anal fissures, and may be recommended if other medications haven't helped.
As with GTN ointment, you'll usually have to use calcium channel blockers for at least six 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 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 two to three 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 doctor to check your fissure has healed or is showing adequate signs of improvement.
If the fissure has completely healed, your doctor 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 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 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.
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 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 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, thereby improving 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.