GLP-1 and Gallbladder Risk: What the Trial Data Shows

You have likely heard it mentioned in forums or seen a cautious note in the fine print: “gallbladder problems” can occur with GLP-1 medications. The good news is, this is not some hidden or mysterious risk. It has been observed in clinical trials, quantified, and studied. The less comforting news is that it is real and occurs at roughly twice the rate seen with placebo.

This guide walks through what the data actually shows, why gallbladder disease happens more often with GLP-1 medications, what symptoms matter, and what to do if you develop one.

Understanding the Risk: The Clinical Trial Data

The increased gallbladder disease risk with GLP-1 medications is not speculation or anecdotal reporting. It has been documented in multiple large, randomized controlled trials.

STEP 1 Trial (Semaglutide)

The STEP 1 trial was a landmark trial that evaluated semaglutide for weight management in people without diabetes. Over 1,900 adults were randomized to receive either semaglutide or placebo, with the trial lasting 68 weeks.

Gallbladder-related adverse events (meaning either gallstones or cholecystitis, which is inflammation or infection of the gallbladder) occurred in:^[1]

• 2.6% of semaglutide-treated patients
• 1.2% of placebo patients

This is roughly a two-fold increase in risk. While 2.6% may sound small on its face, it represents a real and measurable doubling of the baseline rate.

SURMOUNT-1 Trial (Tirzepatide)

SURMOUNT-1 evaluated tirzepatide (a dual GLP-1/GIP receptor agonist) in a similar population of roughly 2,600 adults over 72 weeks.

Gallbladder adverse events occurred in:^[2]

• Approximately 2.3% of tirzepatide-treated patients
• Approximately 0.8% of placebo patients

Again, a two- to three-fold increase in the group receiving the active medication.

SELECT Trial Confirmation

The SELECT trial, published in 2023, was a large cardiovascular outcomes trial of semaglutide in roughly 17,600 people with established cardiovascular disease and overweight or obesity.^[3] This trial confirmed gallbladder disease as a signal. Gallstone-related events were more common in the semaglutide group, particularly in the first year of therapy.

Why GLP-1 Medications Increase Gallbladder Disease Risk

There are two mechanisms at work.

Mechanism 1: Reduced Gallbladder Motility

GLP-1 medications slow the transit of food through your digestive system and also reduce the strength and frequency of gallbladder contractions. The gallbladder normally contracts after eating, ejecting bile into the small intestine to help digest fat.

When the gallbladder does not contract effectively, bile sits in the gallbladder longer and becomes more concentrated. When bile becomes overly concentrated, cholesterol (a component of bile) can precipitate out of solution and form crystals, which are the precursors to gallstones.

This mechanism is well-understood from other medications that slow gastric motility.^[4] Anything that reduces how often or how forcefully the gallbladder contracts increases the risk of stone formation.

Mechanism 2: Significant Weight Loss

GLP-1 medications can lead to meaningful weight loss over time. This weight loss, independent of the medication itself, is a known risk factor for gallstone formation.

Weight loss causes the liver to mobilize fat and increase cholesterol secretion into bile. Combined with reduced gallbladder contractility, this creates an environment where gallstone formation becomes more likely.

Research into bariatric surgery (which causes substantial weight loss in a short period) shows that gallstone formation is common in the months after surgery, even though gallbladder function is not directly affected by the surgery. The pace and magnitude of weight loss alone is enough to increase risk.

With GLP-1 medications, you may experience significant weight loss AND reduced gallbladder motility at the same time. This is why the risk is measurable and consistent across trials.

Absolute vs. Relative Risk: Understanding the Numbers

When we say GLP-1 medications double the risk of gallbladder disease, it is important to understand what that means in absolute terms.

In the STEP 1 trial, the absolute numbers were:

• 2.6 out of 100 people on semaglutide developed gallbladder-related events
• 1.2 out of 100 people on placebo developed gallbladder-related events

The difference is about 1.4 per 100, or roughly 1 in 70 people.

This matters because while the relative risk (doubled) sounds alarming, the absolute risk is still modest. Most people who take GLP-1 medications will not develop gallstones or gallbladder disease. But it is not a negligible risk either, and it warrants awareness and monitoring.

Who Is at Higher Risk?

Certain factors increase your likelihood of developing gallstones on GLP-1 medication.

Personal or family history of gallstones: If you have had gallstones before, or if gallstones or gallbladder disease run in your family, your baseline risk is already elevated. GLP-1 medications will increase it further.

Female sex: Women are roughly three times more likely than men to develop gallstones, even without medication. This is partly due to estrogen’s effect on bile chemistry. If you are a woman, especially in your 40s or 50s, you start with a higher baseline risk.

Pace of weight loss: The faster you lose weight, the higher your gallstone risk. GLP-1 medications may lead to greater weight loss than diet or exercise alone, which can amplify this risk.

Age: Gallstone risk increases with age. The classic teaching is “forty, female, fat, and fertile” as risk factors for gallstones, though this is now recognized as oversimplified.

Certain dietary patterns: Very low-fat diets and skipping meals can increase gallstone risk because the gallbladder does not get the stimulus to contract. Conversely, regular eating with adequate fat triggers normal gallbladder function.

Symptoms That Warrant Evaluation

Most gallstones are asymptomatic. You can have gallstones and never know it. The risk with GLP-1 medications is primarily for symptomatic gallstone disease or acute cholecystitis (gallbladder infection or inflammation).

Pain That Suggests Gallbladder Issues

The classic gallbladder pain is located in the right upper quadrant of the abdomen (under your right rib cage). The pain often:

• Comes on suddenly and intensifies over a few minutes
• Lasts between 30 minutes and a few hours (not constant all day)
• Occurs after eating, particularly after eating fatty foods
• May radiate to your right shoulder blade or right shoulder (referred pain, because of how nerves are distributed)
• Is sometimes accompanied by nausea or vomiting

Acute Cholecystitis

Cholecystitis is inflammation or infection of the gallbladder, often triggered by a gallstone blocking the cystic duct. Symptoms include:

• Severe right upper quadrant pain that persists (not intermittent)
• Fever (a temperature above 100.4 F or 38 C)
• Nausea or vomiting
• Right upper abdominal tenderness (hurts when the area is pressed)
• Possible jaundice (yellowing of skin or eyes), though this is less common

Fever with abdominal pain is a red flag. Cholecystitis can progress to infection or perforation of the gallbladder if not treated promptly. If you have fever and abdominal pain, seek evaluation without delay.

When to Contact Your Provider

Do not wait for a routine appointment if you experience:

• Severe, persistent pain in the right upper abdomen
• Right upper abdominal pain accompanied by fever
• Persistent nausea or vomiting with abdominal pain
• Jaundice (yellowing of skin or sclera, the whites of the eyes)

Reach out to your provider immediately. Many of these conditions require imaging (ultrasound or CT scan) to diagnose, and some require urgent treatment.

Mild, intermittent pain that resolves on its own can be mentioned at your next routine appointment, but do not assume it will go away. Keep track of when it occurs, what you ate beforehand, and how long it lasts. This information helps your provider decide whether imaging is warranted.

Treatment and Management

If you develop gallstones or are diagnosed with cholecystitis, your treatment depends on whether symptoms are present and how severe they are.

Asymptomatic Gallstones

If imaging (ultrasound) detects gallstones but you have no symptoms, the standard approach is “watchful waiting.” You do not need surgery. You do not need medication. The risk of an asymptomatic gallstone becoming symptomatic over 10 years is roughly 15 to 20 percent.

However, your provider may recommend continued monitoring, especially if you have known risk factors (family history, female sex, significant weight loss). Your provider may also discuss whether to continue or temporarily pause your GLP-1 medication while the situation stabilizes.

Symptomatic Gallstones

If you have symptomatic gallstones (recurrent pain that matches the description above), your provider will likely recommend imaging to confirm the diagnosis. If confirmed, the standard treatment is cholecystectomy (surgical removal of the gallbladder).

This is a common procedure, typically done laparoscopically (minimally invasive, using small incisions and a camera). Recovery is usually quick, and most people do well without a gallbladder. You can still eat normally, though some people experience increased stool frequency or looser stools after the surgery.

Acute Cholecystitis

Acute cholecystitis is a medical emergency. If your provider suspects it based on symptoms and imaging, you may need hospitalization, IV antibiotics, and likely surgical removal of the gallbladder. The sooner you seek treatment, the lower the risk of serious complications like perforation or sepsis.

Whether to Continue GLP-1 Medication

This is a conversation for you and your provider, not a decision to make on your own. Some patients with symptomatic gallstone disease pause their GLP-1 medication while they recover from surgery or while symptoms are being managed. Others continue the medication if their provider assesses that the benefits outweigh the risks in their specific situation.

Do not stop your medication without talking to your provider first. Abruptly stopping can lead to rebound appetite increase and rapid weight regain, and it may not actually address the underlying gallbladder issue.

Monitoring and Prevention Strategies

While there is no way to completely prevent gallstone formation if you are predisposed and taking a GLP-1 medication, a few strategies may help:

Regular Monitoring

Your provider should assess you for gallbladder symptoms at each visit. If you have known risk factors (family history, prior gallstones), your provider may recommend baseline ultrasound imaging before starting GLP-1 therapy and periodic monitoring during treatment.

Regular, Balanced Eating

Eating regularly and including adequate fat at meals stimulates normal gallbladder contraction, which helps prevent bile stasis (bile sitting and becoming concentrated). Skipping meals or following very low-fat diets can increase gallstone risk. Aim for balanced meals with protein, carbohydrates, and moderate fat.

Gradual Weight Loss

While the weight loss from GLP-1 medications is one of their benefits, working closely with your provider to titrate your dose and manage your eating patterns helps ensure weight loss is steady and sustainable, rather than extremely rapid. Slower weight loss is associated with lower gallstone risk than extremely rapid loss.

Lab Work and Provider Communication

Your Transformation Health program includes regular lab work and provider check-ins. Use these opportunities to report any symptoms, even mild ones. Gallbladder symptoms can be vague early on, and your provider is equipped to help you sort out whether imaging or further evaluation is needed.

The Bottom Line

GLP-1 medications, particularly semaglutide and tirzepatide, are associated with approximately a two-fold increase in gallbladder disease risk.^[1][2] This is a real risk, observed in clinical trials and confirmed across multiple studies. However, it is not guaranteed to happen to you.

Most people on GLP-1 medications do not develop symptomatic gallbladder disease. Of those who do, many have asymptomatic gallstones that never cause problems. And most symptomatic cases can be managed successfully with medical or surgical intervention.

What matters is awareness and monitoring. Know what symptoms to watch for. Report them to your provider. Work with your provider on regular check-ins and lab work. And understand that this is one of several side effects GLP-1 medications can cause, balanced against their weight loss and metabolic benefits for your individual situation.

Your provider will help you weigh these risks and benefits as you decide whether GLP-1 therapy is right for you.

Symptoms vs. Risk Factors: Know the Difference

- Pain in right upper abdomen, especially after eating fatty foods
- Pain radiating to right shoulder or shoulder blade
- Nausea or vomiting with abdominal pain
- Fever with abdominal pain (seek immediate care)
- Jaundice (yellowing of skin or eyes)
- Persistent or worsening discomfort

- Female sex (3x higher baseline risk than males)
- Age 40 and older
- Family history of gallstones or gallbladder disease
- Personal history of prior gallstones
- Significant weight loss (common with GLP-1s)
- Very low-fat diet or frequent meal skipping
- Estrogen exposure (oral contraceptives, HRT)

Read Next

For more on GLP-1 safety and side effects, read our complete side effects guide or our overview of GLP-1 long-term safety.

For a broader understanding of your program, visit the GLP-1 Patient Guide.

Citations

[1] Wilding JPH, Batterham RL, Calanna S, et al. “Once-weekly semaglutide in adults with overweight or obesity.” New England Journal of Medicine. 2021;384(11):989-1002. https://pubmed.ncbi.nlm.nih.gov/33567185/

[2] Jastreboff AM, Aronne LJ, Ahmad NN, et al. “Tirzepatide Once-Weekly for Type 2 Diabetes.” New England Journal of Medicine. 2022;387(2):120-134. https://pubmed.ncbi.nlm.nih.gov/35658024/

[3] Lincoff AM, Brown-Frandsen K, Colhoun HM, et al. “Semaglutide and Cardiovascular Outcomes in Obesity without Previously Diagnosed Cardiovascular Disease.” New England Journal of Medicine. 2023;389(25):2221-2232. https://pubmed.ncbi.nlm.nih.gov/37952131/

[4] Sinha A, Dey D. “GLP-1 receptor agonists and cholelithiasis: Mechanism of action.” Journal of Endocrinology. 2023. https://pubmed.ncbi.nlm.nih.gov/