GLP-1 medications — Coloscopy.com

In short

GLP-1 receptor agonists — semaglutide, tirzepatide, liraglutide, dulaglutide, and others — slow how quickly the stomach empties. That matters for an endoscopy because food or fluid still sitting in the stomach during sedation raises the risk of aspiration. Recent joint guidance from the American Society of Anesthesiologists, the American Gastroenterological Association, and the American Society for Gastrointestinal Endoscopy supports an individualised approach rather than a blanket rule. Do not change your dose without speaking to your prescribing clinician.

What this page covers

What GLP-1 receptor agonists are, why they came up as a question in endoscopy, what current society guidance suggests in plain terms, and the questions worth raising with both your endoscopy unit and the doctor who prescribes the medication.

Which medications are in this class
Why aspiration risk is the issue
The current society framework for holding the dose
The role of clear-liquid prep in lowering risk
Why this is a conversation, not a download from a website

Which medications are in this class

The GLP-1 receptor agonists most often encountered are semaglutide (sold as Ozempic, Wegovy, and Rybelsus), liraglutide (Victoza, Saxenda), dulaglutide (Trulicity), exenatide (Bydureon, Byetta), and lixisenatide. Tirzepatide (Mounjaro, Zepbound) is a dual GIP/GLP-1 receptor agonist; the same considerations apply. Some people take these for type 2 diabetes; others for weight management. Most are weekly injections; semaglutide is also available as a daily oral tablet, and liraglutide as a daily injection.

These drugs work in part by slowing gastric emptying — the rate at which the stomach passes food into the small intestine. That effect helps with appetite and glycaemic control. It also means the stomach can retain solids and fluids for longer than expected, even after a fast that would empty a stomach not on the medication.

Why this came up for endoscopy

Standard preprocedural fasting rules — no solids for several hours, clear liquids only for a defined window — are calibrated to a normally emptying stomach. As use of GLP-1 receptor agonists expanded rapidly for weight management, anaesthesia clinicians began reporting cases where the stomach contained retained food or fluid at endoscopy or during induction of general anaesthesia, despite the patient having fasted as instructed. Aspiration of stomach contents into the airway, while uncommon, can be serious.

This produced a wave of professional guidance starting in 2023 and updated since. The American Society of Anesthesiologists initially suggested holding GLP-1 receptor agonists periprocedurally — typically the dose on the day of the procedure for daily formulations and the weekly dose the week before for weekly formulations. A subsequent joint multi-society statement, including the American Gastroenterological Association and the American Society for Gastrointestinal Endoscopy alongside anaesthesia and surgical societies, refined the approach.

What current guidance says, in plain terms

The shared direction across recent society statements is that decisions should be individualised rather than universal. That means the team weighs several things together: the dose and indication of the GLP-1 medication, how recently it was last taken, whether the patient has gastrointestinal symptoms suggesting delayed emptying (nausea, fullness, abdominal pain after meals), the type of sedation planned, and the bowel preparation used.

Some of the practical patterns that have emerged in routine practice:

For a coloscopy, the bowel preparation itself empties the upper gastrointestinal tract substantially. Many endoscopists view this as risk-reducing relative to procedures where no liquid prep is used.
An extended clear-liquid period before the procedure (longer than the standard fast) is sometimes used as a substitute for, or addition to, holding the medication. This is at the discretion of the team.
Holding the medication for the dose nearest the procedure — the day of for daily preparations, the week-of dose for weekly preparations — is one option that some units recommend, but it is not mandatory in current consensus.
Patients with symptoms suggesting active gastroparesis or significant nausea/fullness while on the medication are treated more cautiously, and the procedure may be delayed or modified.
Decisions are coordinated between the endoscopist, the anaesthesia team if involved, and — critically — the clinician who prescribes the GLP-1.

Guidance is still evolving as more data accumulates. What your specific unit asks of you may differ from what a unit across town or in another country asks. None of this is a sign of disorganisation; it reflects a reasonable area of clinical judgement.

Why you should not change the dose on your own

Holding a GLP-1 receptor agonist is not free of consequence, particularly for people who take it for type 2 diabetes. Blood glucose control can shift; some people with insulin or sulfonylurea co-prescriptions need additional adjustments to avoid hypoglycaemia. For weight-management indications the consequences of a single missed dose are smaller, but the question of when to restart and whether to repeat the slow titration up still belongs to the prescribing clinician.

The endoscopy unit can — and should — tell you what they need from you for safety on the day. The decision to hold or continue your dose, and how to manage your other diabetes medications around any hold, is a conversation with the clinician who prescribes them.

The role of bowel prep

For a coloscopy specifically, the bowel preparation includes drinking large volumes of an osmotic solution that produces watery stool until the effluent is clear. This process, particularly with split-dose timing, empties the upper gastrointestinal tract considerably more than a simple overnight fast. Some specialists view a thorough split-dose prep, with the second dose finishing the recommended interval before the procedure, as moving the day of test closer to the practical equivalent of an extended liquid fast.

This is one reason the dialogue around GLP-1 medications has been somewhat different for coloscopy than for upper endoscopy or for unrelated surgery, where there is no bowel prep clearing the gut beforehand.

What to ask your clinician

I take [medication name] at [dose] every [day/week]. What does your unit recommend for someone on this medication?
Should I hold a dose, and if so, which one? Is this consistent with what my prescribing clinician thinks?
Do you want me to extend my clear-liquid period beyond the usual fast?
Have I had any symptoms — nausea, fullness, vomiting after meals — that should change the plan?
If I take insulin or another diabetes medication alongside the GLP-1, how do those need to be adjusted around any hold?
If I am holding the dose, when do I restart? Do I need to retitrate?
Will the team check the stomach before the coloscopy starts (some units take a brief look in the stomach with the scope before turning to the colon)?
Is the sedation plan being adjusted because of the medication?

Common worries, briefly addressed

I forgot to mention I am on this medication. What now?

Tell the unit as soon as you remember — ideally before you arrive, by phoning the pre-procedure line. They may proceed with adjustments, change the sedation plan, or rebook. Mentioning it on arrival is far better than not mentioning it at all.

Will I have to start the medication over from a low dose if I hold it?

Sometimes. Restarting after a brief hold is often straightforward, but a longer interruption can mean re-titrating to lessen nausea. Your prescribing clinician will tell you what to do.

Can I just have an unsedated coloscopy and avoid the issue?

Aspiration risk is principally a sedation issue, so an unsedated coloscopy reduces that specific risk meaningfully. Whether unsedated coloscopy is right for you depends on your unit's experience and your own preferences. See sedation options.

Do diabetes pills (metformin, SGLT2 inhibitors) require the same plan?

No — those are different medications with different periprocedural considerations. SGLT2 inhibitors in particular are usually held before procedures because of euglycaemic ketoacidosis risk, but again the prescribing clinician decides. See diabetes and bowel preparation.

What about compounded semaglutide or tirzepatide from a clinic?

The same physiology applies. Tell the endoscopy unit exactly what you are taking, including compounded preparations and any dose changes you have made.

Sources

American Society of Anesthesiologists — guidance on GLP-1 receptor agonists and elective procedures
American Gastroenterological Association, American Society for Gastrointestinal Endoscopy and partners — multi-society clinical practice update on perioperative management of GLP-1 receptor agonists
Society of American Gastrointestinal and Endoscopic Surgeons — guidance on GLP-1 medications and elective surgery
British Society of Gastroenterology and the Royal College of Anaesthetists — perioperative considerations for GLP-1 receptor agonists