Anal fissure

Expert reviewer, Mrs Sara Badvie, Consultant Laparoscopic, Colorectal and General Surgeon
Next review due January 2022

An anal fissure is a small tear or ulcer (open sore) in the skin just inside your anus (bottom). It causes severe pain, and sometimes bleeding when you pass faeces. Anal fissures often go away by themselves with some simple self-help measures. But if it doesn’t, there are several treatments that can help.

An image showing an anal fissure

About anal fissure

Anal fissures develop in the skin lining your back passage, just inside your anus (your anal canal). Anal fissures usually develop towards the back of your anus. You can sometimes get one at the front of your anus though, or even both together. If you have a condition that’s causing your anal fissures, like Crohn’s disease, you may get them anywhere around your anus.

If you’ve had an anal fissure for less than six weeks, it’s called an acute anal fissure. If it lasts for longer than six weeks, it’s known as a chronic anal fissure.

Anal fissures are common. It’s thought that around one in 10 people get one at some point in their life. Anyone can get an anal fissure, including children, but it’s most common in people aged 15 to 40.

Causes of anal fissure

For most people who develop an anal fissure, there isn’t any obvious reason why. It’s usually thought to happen if your anal canal has been damaged though, often as a result of a hard or painful bowel movement. As a result, the muscles around your anus (the internal sphincter muscles) spasm and tense up. This reduces the blood supply to the area, which stops the tear from healing properly. Having further hard bowel movements can then make the fissure come back, or get worse.

Sometimes, there is a clear underlying reason why you may develop an anal fissure. These may include the following.

  • Straining when you go to the toilet due to constipation.
  • Being pregnant or giving birth – this can put pressure on your perineum (the area between your anus and vulva).
  • Having an inflammatory bowel disease, such as Crohn’s disease.
  • Having a sexually transmitted infection or a skin infection.
  • Having a condition that affects your skin, such as psoriasis.
  • Taking certain medicines, such as painkillers containing opioids, or having chemotherapy.
  • Having had trauma to your anus, for example, through having anal sex or through surgery.
  • Having bowel cancer.

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Symptoms of anal fissure

If you have an anal fissure, you may have the following symptoms.

  • A sharp, searing or burning pain in, or around, your bottom when you pass faeces. You can continue to feel some pain for hours afterwards. Some people describe the pain of an anal fissure as like passing broken glass.
  • Bleeding when you pass faeces. Not everyone has bleeding with an anal fissure. But if you do, you might see blood in the toilet bowl after you’ve had a bowel movement.
  • Spasms (sudden tightening) in the muscles around your anus when you pass faeces.
  • A tearing sensation in your anus when you pass faeces.

These symptoms may not always be due to an anal fissure. For instance, piles (haemorrhoids) can cause pain in your anus too. See our FAQ below for more information on the difference between anal fissures and piles. If you have any of these symptoms though, contact your GP. It’s always important to seek medical advice if you notice bleeding after passing faeces.

Diagnosis of anal fissure

Your GP will ask about your symptoms and your medical history. They may examine the area too. They’ll ask you to lie on your side with your knees bent towards your chest and gently part your buttocks to do this. They’ll be able to see if there’s a fissure.

If there’s any uncertainty about what’s causing your symptoms, or if initial treatments don’t help, your GP may refer you to see a colorectal surgeon. This is a surgeon who specialises in conditions affecting your bowel and back passage.


Most anal fissures heal by themselves within six to eight weeks. There are a number of things you can do to help it heal, and relieve your pain and discomfort. These include the following.

  • Gradually increase the fibre in your diet, by including plenty of wholegrain foods, fruit and vegetables. This will help keep faeces soft and easier to pass.
  • Make sure you’re drinking enough fluids, especially if you’re increasing your fibre intake.
  • Keep the area clean and dry, to prevent infection.
  • Go to the toilet as soon as you have the sensation of needing a bowel movement, and try not to strain when you go. ‘Holding on’ when you need to pass faeces and straining can make a fissure worse.
  • Try sitting in a warm bath to relieve any pain, particularly after you’ve had a bowel movement.

See our FAQ below for more information on how to help a child who has an anal fissure.

Treatment of anal fissure

If your pain is particularly severe, or your symptoms aren’t improving, there are a number of treatments you can try.


The following medicines can help to relieve pain associated with an anal fissure, or help it to heal.

  • Laxatives or stool softeners, such as ispaghula husk or lactulose. These work by softening your faeces, making them easier to pass. You can buy them over the counter from a pharmacist without a prescription. It’s best to get advice from your pharmacist or GP first though.
  • Over-the-counter painkillers, such as paracetamol or ibuprofen. These can help with the pain of an anal fissure. You can buy these from a pharmacy or supermarket without a prescription. Make sure you read the patient information leaflet in the packet.
  • Anaesthetic ointment (eg lidocaine). Your GP may prescribe this for a few days if you’ve been having extreme pain when you pass faeces. You apply this ointment to your anus to help numb the area before you have a bowel movement.
  • Glyceryl trinitrate (GTN). This is an ointment that helps your internal sphincter muscle to relax. It improves blood flow to your anal area, helping the fissure to heal. Your GP may prescribe this if you’ve had a fissure for over a week, and other measures don’t seem to be helping. You’ll need to use it for six to eight weeks.
  • Calcium-channel blockers (eg diltiazem cream). Like GTN ointment, this medicine relaxes the muscles in your anus and improves blood flow to the area. It’s associated with fewer side-effects than GTN ointment. In some areas, your GP may need to refer you to a colorectal surgeon to get a prescription for this medicine.

Procedures to treat anal fissure

If other treatment options haven’t helped your anal fissure to heal, or it keeps coming back, your GP may refer you to a colorectal surgeon. Your surgeon will talk to you about what other options they may recommend for treating your anal fissure. These may include the following.

  • Botulinum toxin (Botox) injections. In this procedure, your surgeon will apply the injection directly into your internal sphincter muscle. The aim is to temporarily relax this muscle so that your fissure can heal.
  • Fissurectomy. This involves cutting away the damaged skin from around your anal fissure, along with any ‘sentinel’ skin tags (lumps of skin associated with the fissure). Your surgeon may suggest you have this alongside Botox injections.
  • Lateral internal sphincterotomy. This is a type of surgery that involves cutting the sphincter muscles around your anus, to release the tension and let your fissure heal. Your doctor will usually only suggest this after you’ve tried other treatments first, including Botox.
  • Anal advancement flaps. This involves taking healthy skin from your anal lining and using it to replace the broken skin in your fissure. You may have it at the same time as a sphincterotomy, or afterwards if your fissure still doesn’t heal.

You can read more information about each of these procedures in our Anal fissure procedures topic.

Prevention of anal fissure

You can reduce your risk of developing an anal fissure by preventing constipation. This is really important if you’ve already had an anal fissure, as it can help to stop it coming back. You can help to prevent constipation by making sure you have a healthy balanced diet that contains plenty of fibre, drinking enough fluids and exercising regularly.

If you have another health condition that increases your risk of getting an anal fissure, speak to your doctor. They will talk you through how to best manage your condition and reduce your risk of getting an anal fissure.

Frequently asked questions

  • The most common cause of anal fissures in children is constipation, often due to not drinking enough. Children can often ‘hold on’ when they need to have a bowel movement if it’s been feeling painful to pass faeces. This can end up making the fissure worse though, so it’s important to encourage them to go to the toilet as soon as they need to.

    If your child is constipated, your GP will usually prescribe a laxative, such as macrogol (Movicol) or lactulose, for them to take. This will make their faeces softer and easier to pass. The following tips may also help.

    • Make sure that they’re getting enough fluids throughout the day.
    • Have a set time when your child will try and use the toilet. This may be after every meal for five minutes, or before bedtime.
    • Use a reward system, such as a star chart, to help encourage them to use the toilet.
    • Make sure they are following a balanced diet with plenty of fibre. Foods with a high fibre content include fruit and vegetables, baked beans, and wholegrain breads and cereals.

    It’s also important to make sure your child keeps their bottom clean and dry to help their fissure to heal, and to prevent an infection.

    If your child’s fissure isn’t healing after a couple of weeks or it’s unclear what’s causing it, your GP may suggest referring them to a paediatrician for further investigation and treatment. Most of the time, a child’s anal fissure will clear up after treating the constipation. Sometimes, they may need ointments prescribed by your doctor too. It’s rare for a child to need surgery for an anal fissure.

  • It’s common for anal fissures to come back (recur), especially if you don’t stick to advice to change your diet. This includes following a diet high in fibre and drinking plenty of water. It’s best to carry on following these changes even when your fissure has gone. It will help to keep your faeces soft and prevent your fissure coming back.

    Your fissure may also come back if you don’t take an ointment or cream you’ve been prescribed, for as long as was recommended. You usually need to take these treatments for six to eight weeks. It can be tempting to stop using the treatment earlier if your symptoms start to improve. But your fissure may not have fully healed, and then it can get worse again.

    It’s possible for a fissure to return after Botox injections. Sphincterotomy is usually very effective, but there is a small chance of it not working or your fissure coming back. See our topic on Procedures for anal fissures for more information. If you keep getting anal fissures and other reasons have been ruled out, your doctor may suggest some tests to check there’s no underlying cause. Some people with recurrent fissures have an underlying medical condition, such as Crohn’s disease or a sexually transmitted infection, that could be causing the fissure.

  • It can be easy to confuse anal fissures and piles (haemorrhoids). They have some of the same symptoms, such as bleeding from your bottom, and similar causes. But they are different conditions.

    An anal fissure is a small tear or ulcer (open sore) in the skin just inside your anus. Whereas piles, also known as haemorrhoids, are swollen veins and surrounding tissue around your anus or in your back passage.

    Both anal fissures and piles can result from straining when going to the toilet, which can happen if you have constipation. Following a healthy diet high in fibre and drinking plenty of fluids can help to prevent both piles and anal fissures. If you have any symptoms affecting your back passage, such as pain or bleeding from your bottom, it’s important to seek advice from your GP.

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Related information

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  • Reviewed by Pippa Coulter, Freelance Health Editor, January 2019
    Expert reviewer, Mrs Sara Badvie, Consultant Laparoscopic, Colorectal and General Surgeon
    Next review due January 2022