Causes of constipation 

Constipation usually occurs when stools remain in the colon (large intestine) for too long, and the colon absorbs too much water from the stools, causing them to become hard and dry.

Most cases of constipation aren't caused by a specific condition and it may be difficult to identify the exact cause. However, several factors can increase your chances of having constipation, including:

  • not eating enough fibre, such as fruit, vegetables and cereals
  • a change in your routine or lifestyle, such as a change in your eating habits
  • having limited privacy when using the toilet
  • ignoring the urge to pass stools
  • immobility or lack of exercise
  • not drinking enough fluids
  • having a high temperature (fever)
  • being underweight or overweight
  • anxiety or depression
  • psychiatric problems, such as those brought on by sexual abuse, violence or trauma

Medication

Constipation may sometimes be a side effect of a medicine you're taking. Common types of medication that can cause constipation include:

If constipation is caused by medication, the condition will usually ease once you stop taking the medicine. However, you shouldn't stop taking any prescribed medication unless your GP advises you to.

Speak to your GP if you have constipation that's caused by a medicine. They may be able to prescribe an alternative.

Pregnancy

About two in every five women experience constipation during their pregnancy, mostly during the early stages.

Constipation occurs during pregnancy because your body produces more of the female hormone progesterone, which acts as a muscle relaxant.

The bowel normally moves stools and waste products to the anus by a process known as peristalsis. This is when the muscles lining the bowel contract and relax in a rippling, wave-like motion. An increase in progesterone makes it more difficult for the bowel muscles to contract, making it harder to move waste products along.

If you're pregnant, there are ways to safely treat constipation without harming you or your baby. Read more about treating constipation.

Other conditions

In rare cases, constipation can be a sign of an underlying condition, such as:

Babies and children

Constipation in babies and children is quite common. It's estimated that up to one in every three children in the UK has constipation at any time. Poor diet, fear about using the toilet and poor toilet training can all be responsible.

Poor diet

Children who are over-fed are more likely to have constipation, as are those who don't get enough fluids. Babies who have too much milk are also more likely to get constipation. As with adults, it's very important that your child has enough fibre in their diet.

Toilet training

It's important that you don't make your child feel stressed or pressured about using the toilet. It's also important to let your children try things by themselves (when appropriate). Constantly intervening when they're using the toilet may make them feel anxious and may contribute to constipation.

Toilet habits

Some children can feel stressed or anxious about using the toilet. They may have a phobia about using the toilet, or feel they are unable to use the toilets at school.

This fear may be the result of your child experiencing pain when passing stools. This can lead to poor bowel habits, where children ignore the urge to pass stools and instead withhold them for fear of experiencing pain and discomfort. However, if they do this, their condition will only get worse.

Other conditions

In rare cases, constipation in babies and children can be a sign of an underlying condition, such as:

  • Hirschsprung's disease – which affects the bowel, making it difficult to pass stools
  • anorectal malformation – where the baby's anus and rectum don't form properly
  • spinal cord abnormalities – including rare conditions such as spina bifida and cerebral palsy
  • cystic fibrosis – a genetic condition that causes the body to produce thick and sticky mucus, which can lead to constipation

Page last reviewed: 24/12/2015

Next review due: 24/12/2017