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Anal Fissures in children

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This leaflet discusses anal fissures in children, explains what an anal fissure is, how fissures are caused and their treatment. Throughout this leaflet some medical terms are used and are described here for your benefit.

Faeces: Poo, stool.
Defecation: Having your bowels open, doing a poo
Rectum: The very end of your gut where faeces is stored.
Soiling: Involuntary passage of faeces produces ‘skid marks’ or ‘accidents’.

The relationship between anal fissures and constipation

Children who are found to have an anal fissure are often found to be constipated. Constipation is where the child defecates less frequently than is normally required, so that the lower bowel becomes full of faeces and over stretched. This can cause difficulty for the child to know when to defecate, and can result in poo ‘leaking’ out through their bottom, resulting in soiling. The faeces may also be hard.

What is an anal fissure?

Anal fissures are common and usually occur in pre school children. An anal fissure is caused by the passage of hard faeces which tears the delicate anal lining. The tear means that defecation becomes very painful, the child may scream and blood may be seen on the faeces or toilet paper.

A cycle can easily develop as follows:

Written diagram showing the movement of poo through body

To break this cycle it is important to make the faeces soft and ensure defecation is regular. Regular, soft faeces usually allow healing of the fissure. Despite healing, the memory of the pain and anticipation of it last much longer. It is therefore critical that treatment is not stopped, but gradually weaned down.


The aim of treatment is to ensure that soft faeces are passed regularly with minimal straining. This can be achieved by:

  1. Ensuring a good fluid intake
  2. Encouraging a balanced nutritional diet which contains plenty of fruit
  3. Use of a laxative. Movicol is the most common laxative used but others may include Lactulose or Senokot.


Movicol is the most common laxative advised for use in children. Movicol is also available for adults and whilst this version may be used in some teenagers, it is essential that only the children’s Movicol (called Movicol Paediatric) is given to children. Movicol is called a ‘Macrogol’ laxative; this means that it helps to soften stools by absorbing water. Movicol can be given long term as a ‘maintenance dose’ (that is, a regular dose given every day) or, in the short term, to clear constipation by giving increasing doses. Your specialist team will advise you what doses to give your child. Movicol comes as a powder in a sachet. The powder needs to be mixed with a drink before it is taken.


Lactulose is a modified sugar (‘lactose’ is the sugar found in milk). Lactulose is not absorbed but instead, it passes through the stomach and the small bowel and into the large bowel (‘colon’). Lactulose draws water into the colon making faeces soft. However, lactulose needs to be given at regular intervals during the day (usually two or three times daily) with meals.


The active ingredient in senokot is similar to ones found in prunes and figs. Senokot works differently to lactulose. Instead of softening faeces, senokot makes the bowel contract, pushing the faeces along. This usually happens six to ten hours after senokot is taken, therefore, if your child is given senokot at bedtime they will usually defecate after breakfast.

What are the side effects of laxatives?

  1. Too much laxative can produce diarrhoea.
  2. Lactulose is very sweet so extra care should be taken with cleaning your child’s teeth. Lactulose can cause wind which can be uncomfortable.
  3. When taking senokot there may well be stomach cramps (colic) caused by the bowel contracting and pushing the faeces along. (However, constipation can also cause stomach cramps).
  4. Most laxatives can be given even when your child is taking other medications but it is important that you tell your nurse or doctor if your child is taking other medicines.

Doses of drugs

The treatment of constipation with laxatives is very different from the treatment of other illnesses with medicines such as antibiotics. Antibiotics need to be given in an accurate dose, at fixed times and for a fixed number of days. In contrast, every child requires a different dose of laxative. The correct dose for the child is the one that will consistently produce regular soft faeces. It can take a few days or weeks to find the correct dose for each individual child.

Length of treatment

There are no risks involved with taking laxatives for prolonged periods of time. If your child has been having problems with their bowels for six months or more it may well take that length of time to sort them out completely. When the bowel is full of hard faeces it becomes over stretched. As it shrinks back to its normal size it will function more efficiently and therefore the need for laxatives is reduced. However, treatment can not be simply stopped suddenly. The worst thing that can happen is for the correct doses of laxative to be reached, your child to defecate daily and then for treatment to be stopped suddenly because everything will revert back to the original constipated state.

Having established the correct dose of laxative for your child it is important to continue treatment for at least one month to allow the bowel to settle into its new rhythm. After at least one month has passed the dose can be reduced very slowly. If the problems re-occur, then increase back to the original dose.


  • Encourage your child to drink plenty of fluids and to eat fruit and vegetables.
  • Brush teeth after giving laxatives (especially Lactulose) to prevent tooth decay.
  • The correct dose of laxative is being given when your child is producing regular soft faeces.
  • Keep giving the correct dose for at least one month before trying to gradually reduce it.

For more information or questions please call:

Clinical nurse specialists: 01223 586973 (08:00 to 18:00 Monday to Friday)

Ward or clinic………………………………………………………………………………

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