Bowel preparation for Colonoscopy

Good bowel preparation is important to allow adequate viewing of the colon during colonoscopy. This allows accurate identification of any abnormalities including polyps and the safe removal of any polyps that are found.
In general, bowel preparation involves three steps. Firstly you will go onto a low-residue diet, usually starting 2 days before the procedure. Secondly you will start a liquid-only (‘clear-fluid’) diet usually the day before the procedure. Thirdly you will take the prescribed bowel preparation which usually comes in 2 or 3 separate doses. Bowel preparation will usually cause watery diarrhoea starting soon after the first dose.

Bowel preparation can cause dehydration and disturbance of the balance of salts in the body. It is important to take the bowel preparation in the way it is prescribed and drink plenty of fluid to avoid dehydration.

The information about bowel preparation on this website is general advice only. There are a number of different bowel preparations available. The choice of appropriate bowel preparation and the procedure for modifying your diet and taking the bowel preparation depends on factors including the time of your procedure, your overall health and the presence of any other medical conditions.

A personalised plan will be generated for your bowel preparation during the consultation prior to colonoscopy. This will include the type of bowel preparation used, when it is to be taken, dietary modifications in the days prior to colonoscopy and any changes to your usual medications. People with diabetes or kidney disease need particular care with bowel preparation and this should be discussed during your consultation.

If you have unanswered questions about the procedure please phone your Gastroenterologist.  Further information is available from the Gastroenterological Society of Australia on their ‘consumer information’ page at