GLP-1 Medications and Endoscopy

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GLP-1 medications, the injectable and oral drugs now widely prescribed for type 2 diabetes and weight management, work in part by slowing how quickly the stomach empties. That one effect explains most of their digestive side effects, and it is also why they come up when you schedule an upper endoscopy or colonoscopy with sedation. This guide explains how GLP-1 medications affect the digestive system, which symptoms deserve a call to a physician, and what the current professional guidance says about taking them before a procedure.

This article is general education, not medical advice. Do not stop, skip, or change the dose of any medication on your own. Decisions about a GLP-1 medication belong with the clinician who prescribes it and the team performing your procedure.

What GLP-1 medications are

GLP-1 stands for glucagon-like peptide-1, a hormone the body releases after eating. GLP-1 receptor agonists are medications that act on the same receptors. The group includes semaglutide (Ozempic, Wegovy, Rybelsus), liraglutide (Victoza, Saxenda), and dulaglutide (Trulicity). Tirzepatide (Mounjaro, Zepbound) acts on the GLP-1 receptor and on a second receptor called GIP, and is usually discussed alongside them. Some are taken once a week, some once a day, and some as a tablet.

The Food and Drug Administration (FDA) prescribing information for semaglutide describes several actions: the medication stimulates insulin release and lowers glucagon when blood sugar is high, decreases calorie intake through its effect on appetite, and delays gastric emptying, meaning food leaves the stomach more slowly. A 2024 guidance document from five medical societies describes this as part of the body's natural "ileal brake", the signal that slows the stomach when food reaches the small intestine.

How GLP-1 medications affect the digestive system

Digestive symptoms are the most common side effects of GLP-1 medications. In the adult weight-management trials summarized in the current FDA prescribing information for Wegovy (semaglutide 2.4 mg weekly injection), the following were reported more often with the medication than with placebo:

• Nausea: 44 percent with the medication, 16 percent with placebo.
• Diarrhea: 30 percent, compared with 16 percent.
• Vomiting: 24 percent, compared with 6 percent.
• Constipation: 24 percent, compared with 11 percent.
• Abdominal pain: 20 percent, compared with 10 percent.

Indigestion, bloating, belching, gas, and reflux symptoms were also reported more often than with placebo. These figures come from one medication at one dose, and rates differ among the drugs in the class, so they are a general picture and not a prediction for any one person.

Most people did not stop treatment because of these symptoms. In the same trials, 6.8 percent of people taking the medication stopped because of a side effect, compared with 3.2 percent taking placebo, and nausea, vomiting, and diarrhea were the most common reasons.

When digestive side effects of GLP-1 medications are most likely

The multisociety guidance identifies the situations in which stomach slowing and digestive symptoms are more likely:

• The dose-escalation phase. The early months, when the dose is being stepped up, carry a higher risk of delayed stomach emptying than the maintenance phase.
• Higher doses. The higher the dose, the more likely digestive side effects become.
• Weekly formulations. Digestive side effects are more common with weekly than with daily medications.
• Other conditions that slow the gut. The guidance names gastroparesis, bowel motility disorders, and Parkinson's disease as examples.

If you already live with slow stomach emptying, the FDA prescribing information is direct: semaglutide is not recommended for people with severe gastroparesis. That is a conversation to have with the prescribing clinician before starting, not after symptoms appear.

Managing everyday symptoms

The prescribing clinician manages the dose and schedule, and that is usually where persistent symptoms are addressed. A gastroenterologist can help when the picture is unclear, for example when nausea or vomiting continues at a stable dose, when constipation does not respond to the usual measures, or when it is not obvious whether the medication or an underlying digestive condition is responsible. New digestive symptoms in someone taking a GLP-1 medication are often caused by the medication, but not always, and the usual warning signs still apply.

Less common digestive risks of GLP-1 medications

The FDA prescribing information lists several less common but more serious digestive concerns. They are uncommon, and knowing the symptoms is the practical point.

Gallbladder problems

The prescribing information states that treatment is associated with an increased occurrence of gallstones and gallbladder inflammation. In the adult weight-management trials of the injection, gallstones were reported in 1.6 percent of people taking semaglutide and 0.7 percent taking placebo, and gallbladder inflammation in 0.6 percent and 0.2 percent. Separately, the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) notes that losing weight quickly, by any method, may raise the chance of forming gallstones. Pain in the upper right or upper middle abdomen, especially after meals, with or without fever or yellowing of the skin, should be evaluated.

Pancreatitis

Acute pancreatitis has been observed in people treated with GLP-1 receptor agonists. The prescribing information describes the symptom to watch for as persistent or severe abdominal pain, sometimes spreading to the back, with or without vomiting, and directs that the medication be discontinued if pancreatitis is suspected. Pain of that kind needs prompt medical attention.

Severe symptoms and dehydration

In the adult trials, severe digestive side effects were reported in 4.1 percent of people taking the semaglutide injection and 0.9 percent taking placebo. Reports received after approval include intestinal blockage, ileus (a bowel that temporarily stops moving), and severe constipation with impaction. The prescribing information also notes reports of kidney injury, mostly in people who became dehydrated from vomiting or diarrhea. Vomiting that prevents you from keeping fluids down, a swollen and painful abdomen, or an inability to pass stool or gas should not wait for a routine appointment.

Why GLP-1 medications matter before an endoscopy

Sedation relaxes the reflexes that normally protect the airway. If the stomach still holds food or liquid, there is a small chance it can come back up and be breathed into the lungs, which is called aspiration. Fasting instructions exist to prevent this, and our guide to colonoscopy sedation explains them in more detail.

Because GLP-1 medications slow stomach emptying, the standard fasting window does not always leave the stomach empty. The FDA added a warning to the labels of these medications describing rare reports of aspiration in people having procedures under general anesthesia or deep sedation who had food remaining in the stomach despite following fasting instructions. The label is also candid about the limits of current knowledge. It states that available data are insufficient to say whether changing fasting instructions or temporarily stopping the medication reduces the risk, and it asks patients to tell their health care providers about the medication before any planned surgery or procedure.

Retained food also matters for a practical reason. During an upper endoscopy, the physician needs a clear view of the stomach lining. Food in the stomach can hide what the exam is meant to find, and the procedure may have to be stopped and rescheduled.

What current guidance says about GLP-1 medications before a procedure

This is an area where advice has changed more than once in a short time, so instructions you received for a procedure two or three years ago may not match what you are told today.

How the guidance has changed

• 2023, American Society of Anesthesiologists (ASA). The first widely used guidance advised holding a daily GLP-1 medication on the day of a procedure and a weekly one for a week beforehand.
• Late 2023, American Gastroenterological Association (AGA). The AGA's rapid clinical practice update stated that there was not enough evidence to require stopping these medications before endoscopy and that the approach should be individualized. It noted that for people with diabetes, holding the medication may carry more risk from high blood sugar than benefit, and that a liquid diet the day before endoscopy may be more acceptable than stopping the medication.
• October 2024, multisociety guidance. The ASA, the AGA, the American Society for Metabolic and Bariatric Surgery, the International Society of Perioperative Care of Patients with Obesity, and the Society of American Gastrointestinal and Endoscopic Surgeons published joint guidance intended to replace the conflicting earlier advice.
• 2025, American Society for Gastrointestinal Endoscopy (ASGE). The ASGE's position statement suggests a liquid diet for 24 hours before an endoscopic procedure for patients taking GLP-1 medications, and recommends checking for symptoms of slow stomach emptying just before the procedure and discussing aspiration risk with patients.

What the multisociety guidance recommends

The 2024 multisociety document makes two central recommendations. First, the use of GLP-1 medications around a procedure should be a shared decision among the patient, the team performing the procedure, the anesthesia team, and the prescribing clinician, weighing the person's metabolic need for the medication against individual risk. Second, care should include steps to lower the risk of aspiration from delayed stomach emptying.

In practical terms, the guidance says:

• GLP-1 medications may be continued before a procedure in people who do not have the risk factors listed earlier: dose escalation, higher doses, weekly dosing, digestive symptoms, or another condition that slows the stomach.
• When risk is elevated, holding the medication has to be balanced against the harm of doing so, such as high blood sugar in a person with diabetes. The risk assessment should happen far enough ahead of the procedure to allow changes in the plan.
• A liquid diet for at least 24 hours before the procedure can be used when there is concern about delayed stomach emptying.
• If the decision is made to hold the medication, the right length of time is not known. The guidance suggests following the original ASA approach: the day of the procedure for daily medications and a week before for weekly ones.
• Everyone should be assessed on the day of the procedure for symptoms that suggest a full stomach. When there is concern, the team may use a bedside stomach ultrasound where it is available, change the anesthesia plan to protect the airway, or postpone.

The authors describe the document as guidance based on pharmacology and clinical experience, not an evidence-based guideline, and state that it may need revision as research accumulates.

What newer research adds

Research published since then supports the attention on diet. In a small randomized trial at two United States centers published in JAMA Internal Medicine in 2026, adults having an elective upper endoscopy were assigned to continue their GLP-1 medication or hold one dose. Among 60 participants, a clinically significant amount of retained stomach contents was found in 25 percent of those who continued the medication and about 3 percent of those who held a dose, and the trial was stopped early. Among the participants who were also having a colonoscopy, and so had been on clear liquids the day before, none had significant retained contents in either group.

One small trial does not settle the question, and it measured retained stomach contents, not harm to patients. It does help explain why many practices now ask people taking GLP-1 medications to follow a clear liquid diet the day before an upper endoscopy, and why instructions may differ from one person to the next and from one practice to another.

GLP-1 medications and colonoscopy

A colonoscopy already involves a clear liquid diet the day before, which is the same step the guidance uses to reduce the risk of a full stomach. That is reassuring, but it does not make the medication irrelevant. Sedation is still involved, and anything that slows the digestive tract is worth factoring into how a bowel prep is planned. Our guides to colonoscopy prep and to what happens after an inadequate bowel prep cover the prep itself. The step that matters most is telling the office that schedules your colonoscopy that you take a GLP-1 medication, including the dose and the day of the week you take it.

What to tell your care team about GLP-1 medications

The guidance depends on the procedure team having accurate information early. When you schedule an endoscopy or colonoscopy, it helps to share:

• The name of the medication, the current dose, and whether it is taken daily or weekly.
• For a weekly medication, the day you take it.
• How long you have been taking it and whether the dose was increased recently.
• Why it was prescribed: diabetes, weight management, or another reason.
• Any nausea, vomiting, bloating, abdominal pain, or constipation you have noticed, and any history of gastroparesis.
• Who prescribes it, so the teams can coordinate if a change is being considered.
• Whether the medication comes from a compounding pharmacy or an online service. It may not appear on your pharmacy list, and it counts.

On the day of the procedure, tell the staff if you have nausea, vomiting, bloating, or a sense that food is sitting in your stomach, even if you followed every instruction. That information is used to keep you safe, and a postponed procedure is a better outcome than a preventable complication.

If you take a GLP-1 medication for diabetes, ask the prescribing clinician how to manage blood sugar during a liquid diet and a fasting period. The multisociety guidance specifically warns that withholding the medication can lead to high blood sugar and that bridging to another treatment has its own risks.

When to see a gastroenterologist while taking GLP-1 medications

Mild nausea or a change in bowel habits in the first weeks of treatment is common and is usually managed by the prescriber. Consider a digestive evaluation, or ask your prescriber about one, when:

• Nausea, vomiting, or abdominal pain persists at a stable dose or keeps you from eating and drinking normally.
• Reflux or heartburn is new or worsening. Our guide to GERD and acid reflux describes how it is evaluated.
• Constipation does not improve with the usual measures.
• You have upper abdominal pain after meals, which can point to the gallbladder.
• You notice blood in the stool, black stools, trouble swallowing, or weight loss beyond what you and your prescriber expected. These are not typical medication side effects and should be evaluated whatever the cause.

Severe abdominal pain, repeated vomiting with an inability to keep fluids down, or a swollen abdomen with no stool or gas calls for urgent care. Our guide to when to see a gastroenterologist covers how to tell a scheduled concern from an urgent one. For the source documents, the multisociety GLP-1 guidance announcement from the American Society of Anesthesiologists and the FDA prescribing information on DailyMed, from the National Library of Medicine, are both freely available.

Planning a procedure around GLP-1 medications in Northern Virginia with GC of NoVA

Gastroenterology Center of Northern Virginia sees adults across Arlington, Annandale, and the surrounding communities for upper endoscopy, colonoscopy, and the evaluation of digestive symptoms, including symptoms that begin after starting a new medication. If you take a GLP-1 medication, tell us when you schedule. Our physicians review your medication list, your symptoms, and the procedure planned, and give you written instructions for diet, fasting, and medications that fit your situation. When a change to a GLP-1 medication is being considered, that decision is made together with the clinician who prescribes it. We see patients at our Arlington office, next to VHC Health, and our Annandale office, in the Woodburn Medical complex.

If this is your first visit, our guide to your first gastroenterologist visit explains what to bring. A complete medication list, with doses and the day you take any weekly medication, is the most useful item. To schedule, contact our Arlington office at (703) 522-7476 or our Annandale office at (703) 560-6106, or learn more at gcofnova.com.

This article is for general education and is not medical advice. Talk with a qualified gastroenterologist about your symptoms, diagnosis, and treatment options.