Glycoprep-O Bowel Prep for Your Colonoscopy: A Step-by-Step Guide
- Your prep is the Glycoprep-O Kit: 3 Glycoprep-O (orange) sachets, 3 bisacodyl tablets and 1 magnesium citrate sachet.
- The cleaner your bowel, the more accurate your colonoscopy — follow the timings on this guide and on your appointment letter.
- The day before: low-fibre diet, then bisacodyl at 2 pm, magnesium citrate at 5 pm, and Glycoprep-O from 7 pm (saving the final litre for the morning).
- Expect diarrhoea soon after starting — stay close to a bathroom and keep sipping clear fluids.
A colonoscopy is only as good as the prep. If the bowel is clean, Dr Goutham sees everything clearly and nothing is missed; if it is not, the test may need to be repeated. This guide walks through the Glycoprep-O Kit we use at Colonoscopy Brisbane, step by step.
Always follow the exact times on your appointment letter — they are tailored to your procedure time. If anything is unclear, call us on 07 3733 1551.
What’s in the Glycoprep-O Kit
Buy the Glycoprep-O Kit from your chemist or the clinic. It contains:
- 3 × Glycoprep-O (orange) 70 g sachets
- 3 × bisacodyl 5 mg tablets
- 1 × magnesium citrate sachet
Four days before — low-fibre diet
Stop any medicine containing iron (check with your doctor if you are not sure), and start a low-fibre diet.
| Only eat & drink | Do not eat & drink |
|---|---|
| Food: eggs, low-fat plain yoghurt, skim milk, white bread, white pasta, white rice, steamed white fish, boiled chicken, well-cooked peeled potato. | Food: fruits, vegetables, brown bread, cereals, nuts, seeds, yellow cheese. |
| Drink: water, tea or coffee with skim milk only (or black), and any drinks that contain skim milk only. | Drink: alcohol, Metamucil, fruit or vegetable smoothies. |
The day before — diet and the timed prep
- Mix the three Glycoprep-O sachets with 3 litres of water and refrigerate, so it is cold and ready to drink.
- Eat a low-fibre breakfast (only the foods listed above). If you take a GLP-1 agonist medication, skip breakfast.
- No more solid food after a late breakfast (no lunch or dinner), but keep drinking liquids — have 1 glass of water or an approved drink every hour to stay hydrated.
| Time | What to do |
|---|---|
| 2:00 pm | Take the 3 bisacodyl tablets. These act as stool softeners and may start a bowel motion. |
| 5:00 pm | Dissolve the magnesium citrate sachet in a glass of water and drink the mixture. |
| 7:00 pm | Drink 2 litres of Glycoprep-O, keeping the final 1 litre for the morning. Have 1–2 glasses every 15–20 minutes until the 2 litres are finished. Sip clear fluids alongside to stay hydrated. |
| Before bed | Set an alarm for 4:00 am to finish the remaining preparation. |
The morning of your colonoscopy
If your colonoscopy is in the morning
- At 4–5 am, drink the final 1 litre of Glycoprep-O.
- You may keep sipping clear fluids up to 200 mL (one glass) until 2 hours before your procedure time.
- 6:00 am: take your usual morning medications with a small sip of water, unless told otherwise.
- No chewing gum or lollies.
If your colonoscopy is in the afternoon
- 6:00 am: take your usual morning medications with a small sip of water, unless told otherwise.
- 8–9 am: drink the final 1 litre of Glycoprep-O, 1–2 glasses every 15–20 minutes until finished.
- You may keep sipping clear fluids up to 200 mL until 2 hours before your procedure time.
- No chewing gum or lollies.
Tips to make prep easier
- Keep the made-up Glycoprep-O cold — most people find it more palatable chilled.
- Use a barrier cream around the back passage to prevent soreness.
- Stay home once the prep starts and keep the bathroom stocked.
- Arrange a driver — you cannot drive yourself home after sedation.
Medication and safety notes
Tell the clinic in advance if you take blood thinners, diabetes medication or iron, as these often need adjusting before the test. If you have significant kidney or heart disease, your prep may be modified. When in doubt, call us on 07 3733 1551 rather than guessing.
Frequently asked questions
How long does Glycoprep take to work?
It usually starts working within an hour or two of drinking it, producing several loose, increasingly watery motions. Stay near a bathroom from the time you begin the Glycoprep-O.
How long does the diarrhoea last?
The active phase generally settles within about 2 to 3 hours of your last drink, though it varies between people. Most patients are comfortable to travel to the clinic once the morning effects have passed.
What can I eat before a colonoscopy?
For four days, eat low-fibre foods and avoid fruit, vegetables, nuts, seeds and skins. The day before, switch to clear fluids only after a late breakfast, and have nothing further by mouth from the cut-off time on your letter until after the procedure.
Can I drive after a colonoscopy?
No. Because you are sedated, you must not drive for the rest of the day — arrange someone to take you home and stay with you.
General information, not personal medical advice. Always follow the instructions on your appointment letter. Last medically reviewed by Dr Goutham Sivasuthan, FRACS, June 2026. AHPRA MED0002000354.
Related reading
More guides from the Colonoscopy Brisbane blog:
COLONOSCOPY BRISBANE
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