Ozempic, Mounjaro and Colonoscopy: What Brisbane Patients Need to Know

GLP-1 medicines are now widely used for type 2 diabetes and weight management. If you take one and are booked for a colonoscopy or gastroscopy, the most important step is simple: tell the booking and pre-admission team early.

Medicines such as Ozempic and Wegovy (semaglutide), Mounjaro (tirzepatide), Trulicity (dulaglutide), Victoza and Saxenda (liraglutide) can slow stomach emptying. That may affect fasting, sedation and bowel preparation. It does not automatically mean your procedure must be cancelled or your medicine must be stopped.

Why GLP-1 medicines matter before sedation

GLP-1 medicines can delay the movement of food and fluid from the stomach. During deep sedation or anaesthesia, retained stomach contents can move into the lungs. This is called aspiration. It is uncommon, but it can be serious, which is why the anaesthetic and endoscopy teams need an accurate medication history.

The medicine can also cause digestive effects such as nausea, vomiting, early fullness or constipation. For some people, these symptoms can make bowel preparation harder to complete or reduce the chance of a clean view of the bowel.

This is a planning issue, not a reason to feel embarrassed. The team wants to know so it can reduce avoidable risk and decide whether any part of your preparation needs to change.

What to tell the booking team

Contact the practice or hospital before your procedure and provide:

• the medicine name, including whether it is an injection or tablet
• why you take it, such as diabetes or weight management
• the dose and whether you take it daily or weekly
• the date and time of your most recent dose
• whether your dose has recently increased
• any nausea, vomiting, reflux, early fullness, bloating or constipation
• other diabetes medicines, insulin or medicines that affect digestion

Bring an up-to-date medicine list on the day. If you use an unregistered or online “peptide” product, tell the team exactly what the label says. This information is used for safety, not judgement.

Should you stop Ozempic or Mounjaro before a colonoscopy?

Do not stop it on your own. Current Australian multi-society guidance does not recommend routinely stopping GLP-1 or dual GLP-1/GIP medicines before elective sedation. Stopping can affect blood glucose management and may disrupt the treatment plan agreed with your prescriber.

Your plan still needs to be individual. The procedural team may consider your symptoms, the timing and type of procedure, your diabetes control, other medicines and the local hospital policy. If a change is needed, the appropriate clinician should explain what to do and how to manage the underlying condition safely.

Advice has changed as evidence has developed. Instructions given for a procedure a year or two ago may not be the instructions used today.

How might fasting or bowel preparation be different?

Australian guidance commonly includes a clear-fluid period before elective procedures for people using these medicines, followed by specific fasting instructions. A colonoscopy also requires bowel-cleansing medicine so the lining of the colon can be seen clearly.

The exact timing and allowed fluids must come from your procedure team. “Clear fluid” has a specific medical meaning; milk, smoothies and drinks containing fibre are generally not treated as clear fluids. Your hospital instructions take priority over generic advice.

If you use insulin or other diabetes medicines, preparation may also affect your blood glucose. Ask the team who should coordinate your diabetes plan. Do not guess, and do not extend fasting beyond the instructions in the hope of making the procedure safer.

Why a clean bowel still matters

A colonoscopy is most useful when the endoscopist can inspect the bowel lining properly. Solid stool or cloudy fluid can hide small areas of the lining and make it harder to identify polyps or other changes. If the preparation is inadequate, the procedure may take longer, be incomplete or need to be repeated earlier than planned.

GLP-1 medicines do not automatically cause poor bowel preparation. However, constipation, reduced food intake, nausea and difficulty drinking the required volume can all affect how preparation goes. That is why the team needs to know both the medicine and the symptoms it is causing. Simply stopping an injection without advice does not guarantee a clean bowel and may create a separate problem with diabetes or treatment continuity.

If you often have constipation, have struggled with bowel preparation before, take medicines that slow the bowel or have had abdominal surgery, mention this when you book. The clinician may need to review the preparation plan, but any adjustment should be written specifically for you. Do not add extra laxatives, extend a liquid diet or repeat doses unless the treating team tells you to.

During preparation, follow the permitted-fluid list and the timing of each dose. If you cannot keep the solution down, are passing little or no stool, or the preparation is not progressing as described in your instructions, use the contact pathway provided by the practice or hospital rather than waiting until arrival.

What if you are having a gastroscopy as well?

Some patients have a gastroscopy and colonoscopy during the same appointment. A gastroscopy examines the oesophagus, stomach and first part of the small bowel. Because GLP-1 medicines can slow stomach emptying, the medication history and any symptoms of retained food are particularly relevant when the upper digestive tract is being examined.

Tell the team if you have persistent early fullness, vomiting, regurgitation, marked reflux or the feeling that food remains in the stomach for an unusually long time. Also mention a diagnosis such as gastroparesis, previous stomach surgery or another medicine that slows digestion. These details help the procedural and anaesthetic teams assess the complete risk picture.

Having both procedures does not mean you should invent a longer fast. Excessive fasting can contribute to dehydration and can complicate diabetes management. Follow the combined preparation instructions supplied for the actual booking. If the gastroscopy was added after the original paperwork was issued, confirm whether you need a revised set of instructions.

Questions to ask before procedure day

It is reasonable to ask for practical clarification. Useful questions include:

• Does the team know the exact GLP-1 medicine and the timing of my last dose?
• Which written fasting and clear-fluid instructions apply to this booking?
• Who should advise me about insulin or other diabetes medicines during preparation?
• What should I do if nausea or vomiting prevents me from drinking the preparation?
• What number should I call after hours if the preparation is not working as expected?
• Should I bring my injection pen, medicine box or a current pharmacy list?
• What happens if the anaesthetist decides it is safer to delay the procedure?

Write the answers beside the preparation schedule so everyone supporting you at home can follow the same plan. If different clinicians have given conflicting instructions, ask the procedure team to reconcile them rather than choosing the advice that seems easiest.

What if you have nausea, vomiting or constipation?

Tell the team before you arrive. Symptoms may change the safest plan, particularly if you cannot keep fluids down, feel unusually full, have not opened your bowels as expected, or cannot complete the preparation.

Seek urgent medical care for severe or worsening abdominal pain, repeated vomiting, a swollen abdomen, fainting, chest pain, breathing difficulty, or symptoms that feel unsafe. In an emergency, call 000.

For milder ongoing digestive symptoms, a gut health assessment in Brisbane can help separate medication effects from other causes. Do not assume every new symptom is caused by the injection.

A practical checklist for Brisbane patients

One week before the procedure, or as soon as you book:

1. Check that the practice has your complete medicine list.
2. Confirm the date and time of your last GLP-1 dose.
3. Read the current preparation instructions from start to finish.
4. Ask who to contact about diabetes medicines or insulin.
5. Arrange transport and support for after sedation.

On the day before and the day of the procedure, follow only the plan supplied by your treating team. If the instructions are unclear or conflict with advice from another clinician, call before making a change.

After the procedure

Sedation instructions, hydration, eating and the timing of your next medicine dose should come from the discharge team and the clinician responsible for the GLP-1 prescription. Do not assume the usual dosing day is automatically correct if the procedure or preparation was difficult.

Before leaving, make sure you know when to restart ordinary eating, what to do if nausea persists and who to contact about blood glucose outside your usual range. Seek urgent care for severe abdominal pain, repeated vomiting, breathing difficulty, fainting, heavy bleeding or other symptoms identified in your discharge advice.

Your next step

If you are arranging a colonoscopy in Brisbane and take a GLP-1 medicine, contact the practice early. Colonoscopy Brisbane provides colonoscopy and endoscopy care across Brisbane, Redland, Logan and Moreton Bay. Call 07 3733 1551 or send a secure enquiry for administrative guidance about your booking and preparation pathway.

This article provides general information and does not replace advice from your prescriber, anaesthetist, hospital or endoscopy team.