Read about diagnosing diarrhoea. Further investigation may be needed if you have persistent or severe diarrhoea.

Most cases of diarrhoea get better within a week, and you may not need to visit your GP.

The information below explains what will happen if you need to see your GP.

Read about when to visit your GP if you have diarrhoea.

Identifying the cause

To identify what's causing your diarrhoea, your GP may ask you questions about:

  • what your stools are like – for example, if they're very watery or contain blood
  • how often you need to go to the toilet
  • whether you have other symptoms, such as a high temperature (fever) 
  • whether you've been in contact with anyone else who has diarrhoea, or have recently travelled abroad – this may mean you have picked up an infection
  • whether you have recently eaten out anywhere – this may mean you have food poisoning
  • whether you're taking medication and if it's recently changed 
  • whether you've been stressed or anxious recently

Stool sample

Your GP may ask you for a stool sample so it can be analysed for signs of an infection if you have:

  • persistent diarrhoea that's lasted more than two weeks
  • blood or pus in your stools 
  • symptoms that affect your whole body, such as a fever or dehydration
  • a weakened immune system – for example, because you have HIV 
  • recently travelled abroad
  • recently been in hospital or been taking antibiotics

Find out how to collect and store a stool sample.

Blood tests

Your GP may suggest you have some blood tests if they suspect your diarrhoea is being caused by an underlying health condition.

For example, your blood can be tested for signs of inflammation, which may suggest inflammatory bowel disease.

Read more about the possible causes of diarrhoea.

Rectal examination

Your GP may recommend a digital rectal examination (DRE) if you have unexplained persistent diarrhoea, particularly if you're over 50.

During a DRE, your GP will insert a gloved finger into your bottom to feel for any abnormalities. It can be useful for diagnosing conditions that affect your rectum and bowel.

Further investigations

If you have persistent diarrhoea and your GP is unable to find the cause, they may refer you to your local hospital for further investigation.

You may have:

  • a sigmoidoscopy – a thin, flexible tube with a small camera and light on one (a sigmoidoscope) is inserted into your bottom and up into your bowel
  • colonoscopy – a similar procedure that uses a larger tube called a colonoscope to examine your entire bowel
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