Anal fissure

Expert reviewer, Mrs Sara Badvie, Consultant Laparoscopic, Colorectal and General Surgeon
Next review due May 2024

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 have a bowel movement (poo). Anal fissures often go away by themselves with some simple self-help measures. But if they don’t, there are several treatments that can help.

About anal fissure

Anal fissures develop in the skin lining your back passage, just inside your anus (your anal canal). They usually develop towards the back of your anus, but you can sometimes get one at the front or even both together. If you have a condition that’s causing your anal fissures – for example, 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. This is called a primary anal fissure. It’s often thought to be the result of a hard or painful bowel movement damaging your anal canal. This can cause the muscles around your anus (the internal sphincter muscles) to spasm and tense up, making you more likely to tear. It also reduces the blood supply to the area, which makes it harder for any tears to heal.

Sometimes, there is a clear underlying cause for your anal fissure. This is known as a secondary anal fissure. Causes of secondary anal fissures include the following.

Constipation – passing a hard poo can cause a tear.
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 skin condition such as psoriasis.
Taking 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.

Symptoms of anal fissure

Anal fissure symptoms may include the following.

A sharp, searing or burning pain in or around your bottom when you poo. Some people describe this as feeling like ‘passing broken glass’. You may continue to feel a deep, burning pain for several hours afterwards.
Bleeding when you poo. Not everyone has bleeding with an anal fissure. But if you do, you might see blood in the toilet bowl or on the toilet paper after you’ve had a poo.
Spasms (sudden tightening) in the muscles around your anus when you poo.
A tearing sensation in your anus when you poo.

These symptoms may not always be due to an anal fissure. Other conditions, like piles (haemorrhoids) can cause similar symptoms. If you have any of the symptoms above, contact your GP for advice. It’s always important to seek medical advice if you notice bleeding from your bottom.

Diagnosis of anal fissure

Your GP will usually be able to diagnose an anal fissure by asking about your symptoms and examining you. They’ll ask you to describe your symptoms and how long you’ve had them. They may also ask you about your health in general and your medical history.

Your doctor will examine you by asking you to lie on your side with your knees bent towards your chest. They’ll then gently part your buttocks to examine the area and 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.

Self-help

Most anal fissures heal by themselves within six to eight weeks. There are a number of ways to help the fissure heal and to relieve your pain and discomfort. These include the following.

Gradually increase the fibre in your diet up to 30g per day by including plenty of wholegrain foods, fruit and vegetables. This will help keep your poo soft and easier to pass.
Make sure you’re drinking enough fluids, especially if you’re increasing your fibre intake.
Keeping the area clean and dry will help with healing and with preventing infection.
Make sure you go to the toilet as soon as you feel the need to poo and try not to strain when you go. ‘Holding on’ and straining can make a fissure worse – this can be a common cycle in children.
Try sitting in a warm bath to relieve any pain, particularly after you’ve had a bowel movement.
Take over-the-counter painkillers such as paracetamol or ibuprofen to help manage any pain. You can buy these without a prescription. Make sure you read the patient information leaflet in the packet.

Treatment of anal fissure

If your pain is particularly severe or your symptoms aren’t improving with self-help measures, there are a number of treatments your doctor may suggest.

Medicines

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

Laxatives or stool softeners such as ispaghula husk or lactulose. These can help if you’re constipated. They work by softening your poo and making it easier to pass. You can buy laxatives over the counter from a pharmacy without a prescription. A doctor will need to prescribe them if it’s for a child.
Anaesthetic ointment (for example, lidocaine). Your GP may prescribe this for a few days if you’ve been having extreme pain when you poo. You apply this ointment to your anus to help numb the area before you have a bowel movement.
Glyceryl trinitrate (GTN) ointment. This helps to relax the sphincter muscles in your bottom, which improves blood flow to the area and helps the fissure to heal. Your GP may prescribe GTN ointment 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. You should keep using the ointment for the full time to prevent your fissure from coming back.
Calcium-channel blockers (for example, diltiazem cream). Like GTN ointment, this medicine relaxes the muscles in your bottom and improves blood flow to the area. It’s associated with fewer side-effects than GTN ointment. This medicine can usually only be prescribed by a specialist colorectal surgeon. Your GP may refer you if you’re not able to tolerate GTN or if you have a chronic anal fissure.

If a child’s fissure doesn’t heal after a couple of weeks, their GP may refer them to a paediatrician.

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. Options include the following anal fissure procedures.

Botulinum toxin (Botox) injections. In this procedure, your surgeon will inject Botox directly into the sphincter muscle in your bottom. The aim is to temporarily relax this muscle so that your fissure can heal.
Fissurectomy. This involves cutting away the damaged skin around your anal 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 in your bottom. This releases the tension around your anus and lets your fissure heal. Your doctor will usually only suggest this after you’ve tried other treatments, 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.

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 that’s healed, as it can help to stop the fissure from coming back. You can help to prevent constipation by making sure you have a healthy balanced diet that contains plenty of fibre. It’s also important to make sure you’re 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 tell you the best way to manage your condition and reduce your risk of getting an anal fissure.

Frequently asked questions

Expand all

What is an anal fissure?

An anal fissure is a small tear in the skin just inside your bottom. It can be very painful when you have a poo.
How do you know if a fissure is healing?

You’ll start to notice your symptoms improving as your fissure is healing. Your pain should lessen and if you had any bleeding, this should stop too. You should have a follow-up appointment with your doctor after six to eight weeks. This is to check that the fissure has healed.
How long do anal fissures take to heal?

Most anal fissures heal within six to eight weeks if you make changes to your diet and lifestyle and take medicines for pain relief. Sometimes, anal fissures heal more quickly than this. Sometimes, they last for longer and you may need further treatment.
Do anal fissures always hurt?

You’ll usually experience severe pain when you have a poo if you have an anal fissure. But it’s also possible to have an anal fissure and not have any pain.
Are anal fissures dangerous?

Anal fissures can be really painful but they’re treatable and aren’t usually a serious problem. But they can sometimes lead to other problems such as infection. If you avoid going for a poo because of a fissure, it can lead to faecal impaction. This is when you have a large blockage of poo in your bowels.
What is a chronic anal fissure?

A chronic anal fissure is one that you’ve had for longer than six weeks. It might mean that you need specialist treatment or a procedure to get rid of your fissure.

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