Anal Fissure

What is an anal fissure?

An anal fissure is a small tear of the skin of the anus. Although the tear of an anal fissure is usually small (usually less than a centimetre), it can be very painful because the anus is very sensitive. The pain tends to be worse when you pass faeces (sometimes called stools or motions) and for an hour or so after passing faeces. Often an anal fissure will bleed a little. You may notice blood after you pass faeces. The blood is usually bright red, and stains the toilet tissue, but soon stops.

Anal fissures are common in both adults and children. They are not usually serious, but they are sore and can be distressing, particularly for children.

In most people the fissure heals within 1-2 weeks or so, just like any other small cut of the skin. Some fissures take longer to heal. A fissure that lasts more than six weeks is called a chronic anal fissure (chronic means persistent.) This is uncommon, but treatment can still be effective.

What causes an anal fissure?

Common causes

Most anal fissures are thought to be due to passing large or hard faeces when you are constipated. The rim of the anus may stretch and tear slightly. Spasm (tightening) of the muscle around the anus (the sphincter) may play a part in causing the tear, or in slowing down the healing process.

In about 1 in 10 cases, the fissure occurs during childbirth. Sometimes an anal fissure occurs if you have bad diarrhoea.

Anal fissures and other conditions

In a minority of cases, a fissure occurs as part of another condition. For example, as a complication of Crohn’s disease or an anal herpes infection. In these situations you will have other symptoms and problems as well. These type of fissures are not dealt with further in this leaflet.

Why do some anal fissures not heal so well and become chronic?

It is thought that the muscle tone (pressure) around the anus is quite high in people with a chronic anal fissure. If the muscle tone around the anus is high, the blood supply to the anus is reduced. This can affect how well the tear heals.

What is the initial treatment for an anal fissure?

In most people the fissure heals within a week or so, just like any other small cut or tear to the skin. Treatment aims to ease the pain and to keep the faeces soft whilst the fissure heals.

Easing pain and discomfort

  • Warm baths are soothing, and may help the anus to relax which may ease the pain.
  • A cream or ointment that contains an anaesthetic may help to ease the pain. You should use this only for short periods at a time (5-7 days). If you use it for longer, the anaesthetic may irritate or sensitise the skin around the anus. You can get one on prescription. You can also buy some of these products at pharmacies without a prescription.
  • A cream or ointment that contains a steroid may be prescribed by a doctor if there is a lot of inflammation around the fissure. Steroids reduce inflammation, and may help to reduce any swelling around a fissure. This may help to any ease itch and pain. You should not use it for longer than one week at a time.
  • Wash the anus carefully with water after you go to the toilet. Dry gently. Don’t use soap whilst it is sore as it may irritate.
  • Painkillers such as paracetamol or ibuprofen may help to ease the pain (but avoid codeine – see below).

Avoid constipation and keep the faeces soft

  • Eat plenty of fibre which is in fruit, vegetables, cereals, wholemeal bread, etc.
  • Have lots to drink. Adults should aim to drink at least two litres (10-12 cups) of fluid per day. You will pass much of the fluid as urine, but some is passed out in the gut and softens the faeces. Most sorts of drink will do, but alcoholic drinks can be dehydrating and may not be so good.
  • Fibre supplements. If a high-fibre diet is not helping you can take fibre supplements (bulking agents) such as ispaghula, methylcellulose, bran or sterculia. You can buy these at pharmacies or get them on prescription. Methylcellulose also helps to soften faeces directly which makes them easier to pass.
  • Toileting. Don’t ignore the feeling of needing the toilet to pass faeces. Some people suppress this feeling and put off going to the toilet until later. This may result in bigger and harder faeces forming that are more difficult to pass later.
  • Avoid painkillers that contain codeine such as co-codamol, as they are a common cause of constipation. Paracetamol is preferable to ease the discomfort of a fissure.

There are separate leaflets called ‘Constipation in Adults’, ‘Constipation in Children’ and ‘Fibre and Fibre Supplements’ that provide more details about fibre and constipation.

Anal fissures in children

The above measures apply to children who have a fissure as much as to adults. In children, the pain often makes them hold on to their faeces. This may lead to a vicious circle, as then even larger and harder faeces form, which cause more pain when they are finally passed. Therefore, in addition to the above measures, a short course of laxatives may be prescribed for children with an anal fissure. The aim is to make sure their faeces are soft and loose whilst the fissure heals.

What if the anal fissure does not heal with the above measures?

An anal fissure will heal within 1-2 weeks in most people, but takes longer to heal in some people. Even if it has lasted six weeks, when it technically becomes a chronic anal fissure, there is still a reasonable chance that it will heal on its own without treatment. However, treatment can help to heal the fissure as quickly as possible.

Treatment aims to:

  • Relax the tone of the muscle around the anus. This allows a good blood flow and enables the fissure to heal as quickly as possible.
  • Keep the faeces soft and easy to pass.

Glyceryl trinitrate ointment

If you apply glyceryl trinitrate (GTN) ointment to the anus, it relaxes the muscle around the anus (the anal sphincter). This may allow the fissure to heal better. It may also ease the pain very quickly. A doctor may advise that you use GTN if you have had an anal fissure for longer than a week or so, and particularly if you have a chronic anal fissure.

GTN may help in some, but not all, cases. Research studies have shown that, for people with a chronic anal fissure, about 5 in 10 fissures healed with GTN treatment. This compared to about 3-4 in 10 that healed with no treatment. So, the effect of GTN is modest, but may well be worth a try.

Some points to note if you use GTN ointment include the following.

  • There is only one branded product of GTN ointment that is used to treat anal fissure. It is called Rectogesic┬« and is only available on prescription. Rectogesic┬« contains 0.4% GTN. You should use this exactly as described on the leaflet that comes with the packet. For example:
    • A standard dose is 2.5 cm squeezed out of the tube. (A measuring line comes with the product to measure 2.5 cm of ointment.)
    • You squeeze a dose of ointment on to a finger (which you can cover beforehand with cling film or similar). You then place the ointment just inside the anus.
    • The ointment is used every 12 hours until pain goes, or for up to 8 weeks maximum. (Some doctors advise to continue with the ointment for a full 6-8 weeks even if the pain goes much sooner. This is because it often takes 6-8 weeks of treatment for the fissure to heal fully, even if the pain has gone.)
    • The product leaflet gives details of whom should not use the ointment and of side-effects that may occur. For example, it should not normally be used by children and pregnant or breast-feeding women.
  • Up to 6 in 10 people have a headache after applying GTN ointment. (The GTN gets into the bloodstream and may cause a headache.) The headache usually goes within 30 minutes. Painkillers such as paracetamol will help if a headache occurs. If headaches are troublesome, try using a smaller amount of ointment for a few days, and then gradually increase the amount back to normal over several days.
  • Another tip if you get bad headaches is to rub a smaller amount of ointment (a pea-sized amount) around the rim of your anus rather than inserting the full amount into the anus. GTN is absorbed more into the bloodstream from the thin skin inside the anus. Using a smaller dose of ointment just on the rim of the anus may avoid side-effects (but may not be as effective as using the full dose inserted into the anus.)


An operation is an option if the fissure fails to heal despite the above treatments. It is also an option if you have recurring fissures. The usual operation is to make a small cut in the muscle around the anus (internal sphincterotomy). This permanently reduces the tone (pressure) around the anus and allows the fissure to heal. This is a minor operation which is usually done as a day case under general anaesthetic.

The success rate with surgery is very high – at least 9 in 10 cases are cured.

As with any operation, there is a risk of complications. After this operation, some people have poor control of gas (wind), and a very small number have soiling of underclothes, or mild bowel incontinence. But, studies have demonstrated that the risk of these complications is small, and the vast majority of people who have this operation are pleased with the result to be free from the symptoms of an anal fissure. And for some, to be free of the problem of recurring anal fissure.

Other medicines

Some studies suggest that other medicines may be useful to relax the anal sphincter muscle and quicken healing. For example, drugs called calcium antagonists have been studied and seem to have some effect. Also, injections of botulism toxin into the anal sphincter muscle have been studied to see if this relaxes the muscle. Further studies are needed to clarify the role of these newer treatments.

Will it happen again?

Some people seem prone to recurring anal fissures. Up to half of people who have a chronic anal fissure successfully treated with GTN ointment will have one or more recurrences at some time in the future. It is thought that these people have an ongoing higher than average pressure (tone) of the muscle around the anus. They are more likely to tear the rim of the anus if it is stretched. However, a further course of GTN ointment can be used to help to heal any future fissure. Surgery may be an option if you have frequent recurrences.

Prevention of a further anal fissure

If you have had one anal fissure, after it has healed you have a higher than average chance of having another one at some time in the future. The best way to avoid a further fissure is not to become constipated by using the measures described above. That is, a high-fibre diet, fluid, etc. Leaflets that list foods high in fibre are commonly available. Ask your practice nurse for one if you cannot obtain one.

References and Disclaimer | Provide feedback


  • Anal fissure, Clinical Knowledge Summaries (May 2008)
  • Nelson R; Non surgical therapy for anal fissure. Cochrane Database Syst Rev. 2006 Oct 18;(4):CD003431. [abstract]
  • Brown CJ, Dubreuil D, Santoro L, et al; Lateral internal sphincterotomy is superior to topical nitroglycerin for healing chronic anal fissure and does not compromise long-term fecal continence: six-year follow-up of a multicenter, randomized, controlled trial. Dis Colon Rectum. 2007 Apr;50(4):442-8. [abstract]
  • Mentes BB, Tezcaner T, Yilmaz U, et al; Results of lateral internal sphincterotomy for chronic anal fissure with particular reference to quality of life. Dis Colon Rectum. 2006 Jul;49(7):1045-51. [abstract]
  • Hyman N; Incontinence after lateral internal sphincterotomy: a prospective study and quality of life assessment. Dis Colon Rectum. 2004 Jan;47(1):35-8. Epub 2004 Jan 14. [abstract]


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