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.
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. 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 GP 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 GP may prescribe a medication called glyceryl trinitrate (GTN), an ointment 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, helping it heal faster.
It can also help reduce the pressure in your anal canal, which should help ease the pain.
The majority of acute fissures, which are 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 this type of GTM ointment, affecting up to half of people using it.
Some people may also feel dizzy or lightheaded after using GTN. It isn't suitable for children and should be used with caution in women who are pregnant or breastfeeding.
If headaches are a problem, reducing the ointment dosage for a few days can help. 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.
Make sure you apply the ointment to the skin around the anus and don't push it inside the anal canal.
You'll usually have to use GTN ointment for at least six weeks, or until your fissure has completely healed.
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 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 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 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.