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The most common cause of constipation is lack of sufficient fibre in the diet. Fibre adds bulk to faeces and makes them soft and easy to pass, so the simplest approach to constipation is to increase fluid and fibre intake, but laxative drugs are often used, either bought over the counter or prescribed by a healthcare professional.

Ignoring the call to stool (or the urge to defaecate) can also cause constipation because the faeces can become hard and dry and because they are small, are difficult to pass because they don’t stimulate the muscles that propel them through the intestine.

Certain drugs and diseases can also lead to constipation. When dealing with the treatment of constipation you should always be aware that the onset of constipation, especially in middle aged or older people may be an early symptom of bowel cancer.

Clinical practice point. Before resorting to laxatives, try:

  • Increasing daily fibre intake, about 30g fibre per day. Further information is available on how to do this on the NHS Choices website How to get more fibre into your diet
  • Add bulking agents, e.g. wheat bran, to diet – these will help to make the stools softer and easier to pass, although bran and fibre can make bloating worse

    N.B. In order to minimise bloating and discomfort, dietary fibre and bulking agents should be introduced gradually into the diet

  • Drink plenty of water
  • Exercise regularly
  • Make time to establish a regular bowel routine by utilising the gastro-colic reflex (i.e. making time to use the toilet after meals)
  • Sitting in the correct position on the toilet

NICE provide guidelines for constipation in children and young people[2] and the use of strong opioids in palliative care in adults[3].

Laxatives are useful for preventing pain and straining if an individual has a hernia or haemorrhoids and may be prescribed after abdominal surgery or childbirth for the same reason and are used to clear the bowel prior to some investigative procedures, ie colonoscopy.

They can be helpful when prescribed for elderly or bedridden patients, but the dose and effectiveness must be monitored carefully, as they can cause diarrhoea if overused.

Check your local policy, but the advice below is generally adopted in most places:

  • Unless otherwise indicated bulk forming laxatives should be the first line treatment and usually start to work after 2-3 days
  • If stools remain hard, an osmotic laxative can be added or given instead
  • If stools are soft but still difficult to pass add a stimulant to the bulk-forming laxative
  • Osmotic laxatives usually start to work after 2-3 days, while stimulants act within 6-12 hours
  • Most laxatives can cause bloating, flatulence, abdominal cramps, nausea and dehydration (look out for signs of light-headedness, headaches, darker urine)

Did you know? Bulk-forming or osmotic laxatives can cause dehydration if the patient is not well hydrated.

A table containing further information about the different types of laxative is available to download in PDF format.


1. How to get more fibre into your diet. NHS Eat well website. [Last reviewed 1 August 2018, cited 3 October 2018] Available from: https://www.nhs.uk/live-well/eat-well/how-to-get-more-fibre-into-your-diet/

2. NICE Clinical Guideline 99. Constipation in children and young people: diagnosis and management. [Last reviewed July 2017, cited 3 October 2018] Available from: https://www.nice.org.uk/guidance/cg99

3. NICE Clinical Guideline 140. Palliative care for adults: strong opioids for pain relief. [Last reviewed August 2016, cited 3 October 2018] Available from: https://www.nice.org.uk/guidance/cg140

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