Bowel prep for colonoscopy

Bowel prep is a laxative you need to drink before having endoscopy procedures to look at your lower bowels.

Unfortunately, prepping your bowel for an endoscopy is something that many people with inflammatory bowel disease (IBD) will need to do. It’s an unpleasant task which generally involves drinking large quantities of a laxative solution from the day before your examination. This solution will make you urgently need the toilet so that your bowel is completely clear to be viewed by the endoscope.

Bowel prep is commonly used for a colonoscopy and sigmoidoscopy - but may also be used for other types of endoscopy.


What will I need to do?

Typically you will be required to fast (not eat any food) for 12-24 hours before the procedure and drink a laxative solution which will give you diarrhoea.

Below is an outline of the typical instructions given to people who are taking bowel prep. This information is only given as an example of what you may expect and you should follow the specific instructions you are given by your doctor when taking bowel prep yourself.

5-10 days before your examination

If you are taking iron tablets then stop taking them.

One week before your examination

If you are taking stool-bulking agents (eg Fybogel or Regulan) stop taking them.

Two days before your examination

Eat a light, low residue diet avoiding cereals, wholemeal bread, salads, fruits or any food containing fibre, nuts or seeds. Continue to drink normally and take your normal medication. Do not have any red or black jellies or drinks.

The day before your procedure

This is for a morning procedure. If you are having an afternoon procedure the timings will be slightly different.

You may have clear fluids only (such as glucose drinks, black tea, or coffee (no milk), lemonade, water, and clear soup) and no food. It is recommended you drink at least 2 to 3 litres of water/fluid during the day before your examination.Do not have any red or black jellies or drinks.

7am: Drink the first dose of bowel preparation

7pm: Drink the second dose bowel preparation

In some people bowel preparation can start to work quickly (as little as 30 minutes) but can take 2-3 hours to start. It can cause violent diarrhoea so it is suggested you stay need a toilet.

No alcohol should be drunk the day before, the day or, or the day after your examination.

Brands of bowel preparation

There are a few different brands of bowel prep which you may be given. These include MoviPrep, Picolax, CitraFleet or Klean-Prep.


If you have any questions before or during taking bowel prep you should contact your IBD team.

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