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Constipation is a common problem. It means either going to the toilet less often than usual to empty the bowels, or passing hard or painful stools (faeces). Constipation may be caused by not eating enough fibre, or not drinking enough fluids. It can also be a side-effect of certain medicines, or related to an underlying medical condition. In many cases, the cause is not clear. Laxatives are a group of medicines that can treat constipation. Ideally, laxatives should only be used for short periods of time until symptoms ease.

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What is constipation?

What is constipation?

Constipation is common. The word may mean different things to different people as bowel habits (and the words they use to describe them) differ greatly between people. For some it might mean not going to the toilet as often as they usually do, for others it means their stools are very hard or painful to pass. This might mean people strain to force the stool out. For others it might feel like they haven't emptied completely, and for some people they only believe they are constipated when they have several of these symptoms at the same time.

A commonly used medical definition is that constipation is when you have fewer than 3 spontaneous bowel movements a week.

Constipation can occur at all ages. Sometimes it occurs because of how your body is; your large intestine might be sluggish and need help expelling the waste, or perhaps the bowel muscles don't work together effectively. Otherwise constipation occurs because of another medical condition, or medicines that you are taking.

Constipation symptoms

If you are constipated it causes one or more of the following:

  • Stools (faeces) become hard and difficult or painful to pass.

  • The time between toilet trips (to do a bowel motion) increases compared with your usual pattern. There is a large range of normal bowel habit. Some people normally go to the toilet to pass stools 2-3 times per day. For others, 2-3 times per week is normal. It is a change from your usual pattern that may mean that you are constipated. In general passing a soft stool at least three times a week is considered normal.

  • Sometimes, crampy pains occur in the lower part of your tummy (abdomen). You may also feel bloated and feel sick if you have severe constipation.

  • It does not feel as though you have emptied your bowel or 'finished' after you have been to the toilet to pass a stool.

Chronic constipation means the problem has been present for at least 12 weeks out of the past 6 months.

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Causes of constipation

Some causes are known to lead to constipation, including the following:

  • Not eating enough fibre (roughage) can lead to constipation. The average person in the UK eats about 12 g of fibre each day. However, 18 g per day is recommended by the British Nutrition Foundation. Fibre is the part of plant food that is not digested. It remains in your gut. It adds bulk to the stools (faeces) and helps your bowels to work well. Foods high in fibre include fruit, vegetables, bran cereals and wholemeal bread.

  • Not drinking much may lead to constipation or make constipation worse. Stools are usually soft and easily passed if you eat enough fibre and drink enough fluid. However, some people need more fibre and/or fluid than others in order to avoid constipation.

  • Some special slimming diets are low in fibre and may cause constipation. For example, diets very low in carbohydrates and some liquid diets.

  • Some medicines can cause constipation as a side-effect. Examples are painkillers (particularly those with codeine, such as co-codamol, or very strong painkillers, such as morphine), some antacids, some antidepressants (including amitriptyline) and iron tablets; however, there are many others. See the list of possible side-effects on the leaflet that comes with any medicine that you may be taking. Tell a doctor if you suspect a medicine is making you constipated. A change of medication may be possible.

  • Various medical conditions can cause constipation. For example:

  • Being less mobile for various reasons, for example:

  • Pregnancy. About 1 in 5 pregnant women will become constipated. It is due to the hormonal changes of pregnancy that slow down the gut movements. In later pregnancy, it can simply be due to the baby taking up a lot of room in the tummy and the bowels being pushed to one side.

Unknown cause (idiopathic)

Some people have a good diet, drink a lot of fluid, do not have a disease and do not take any medication that can cause constipation; however, they still become constipated. Their bowels are said to be underactive. This is quite common and is sometimes called functional constipation or primary constipation. Most cases occur in women. This condition tends to start in childhood or in early adulthood and persists throughout life.

What causes constipation?

Further reading and references

Article history

The information on this page is written and peer reviewed by qualified clinicians.

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