GLP-1 Medication and Gallbladder Problems

Gallbladder problems, mainly gallstones and gallbladder inflammation (cholecystitis), are a recognised side effect of GLP-1 medicines such as Mounjaro (tirzepatide) and Wegovy (semaglutide). The risk appears to be linked largely to rapid weight loss, which is a known trigger for gallstones whatever the cause. In clinical trials, gallbladder events were more frequent on treatment than on placebo, but still affected a small minority of people. Knowing the symptoms of biliary colic, cholecystitis and their complications means you can get help promptly if something goes wrong.

What does the gallbladder do?

The gallbladder is a small, pear-shaped pouch tucked under the liver on the right side of the upper abdomen. It stores bile, a fluid made by the liver that helps digest fats. When you eat, especially fatty food, the gallbladder squeezes and releases bile into the small intestine through a system of tubes called the bile ducts.

The common bile duct joins the pancreatic duct before it enters the intestine. This shared exit is why a gallstone that gets stuck in the wrong place can cause pancreatitis as well as gallbladder problems.

Common gallbladder problems

The NHS notes that gallstones are common and most people with them never have symptoms. Problems usually arise only if a stone causes a blockage.

What the evidence shows for GLP-1 medicines

The most reliable sources for UK readers are the medicines' Summaries of Product Characteristics, which summarise the main clinical trial results.

Mounjaro (tirzepatide)

According to the UK SmPC:

• In pooled SURMOUNT-1, -2 and -3 weight-management trials, acute gallbladder disease was reported in 2.0% of tirzepatide-treated people and 1.6% of those on placebo.
• Cholecystitis was reported in 0.6% on tirzepatide versus 0.2% on placebo.
• Gallstones were reported in 1.1% on tirzepatide versus 1.0% on placebo.
• In a trial in people with heart failure with preserved ejection fraction (HFpEF) and obesity, acute gallbladder disease was reported in 4.4% on tirzepatide versus 2.7% on placebo.
• In the weight-management studies, acute gallbladder events were positively correlated with weight reduction: the more weight people lost, the more likely these events were.

In the SmPC's table of side effects, gallstones are classed as common (between 1 in 100 and 1 in 10 people) in the weight-management trials, and cholecystitis as uncommon (between 1 in 1,000 and 1 in 100).

Wegovy (semaglutide)

According to the UK SmPC for Wegovy 2.4 mg:

• Gallstones were reported in 1.6% of people treated with semaglutide 2.4 mg in the phase 3 weight-management trials.
• Gallstones led to cholecystitis in 0.6% of people on semaglutide 2.4 mg.

The Wegovy SmPC lists cholelithiasis among its recognised side effects. Check the current SmPC or patient leaflet for the exact frequency category, which can be updated over time.

Wegovy is also licensed for some adolescents aged 12 and over. In the adolescent trial described in the SmPC, gallstones were reported in 3.8% of young people treated with Wegovy compared with none on placebo. This is a reminder that gallbladder risk is relevant at any age when weight loss is substantial.

Other GLP-1 medicines

Gallbladder events are considered a class effect and appear in the product information for other GLP-1 medicines too, including liraglutide (Saxenda). Oral GLP-1 medicines are likely to carry similar warnings; check the product leaflet for your specific medicine. Our guide to oral GLP-1 side effects covers tablets.

Why do GLP-1 medicines increase gallbladder risk?

The leading explanation is rapid weight loss, with possible additional direct effects of the medicines.

Rapid weight loss and bile

When you lose weight quickly, the liver releases more cholesterol into bile. At the same time, if you are eating much less, and especially less fat, the gallbladder receives fewer signals to contract and empty. Bile can then sit in the gallbladder for longer, becoming more concentrated, and cholesterol can crystallise into stones.

This effect is not unique to GLP-1 medicines. It is well recognised with very low calorie diets and after bariatric surgery. The NHS lists obesity and losing a lot of weight quickly among the risk factors for gallstones.

Effects on gallbladder movement

Some research has suggested that GLP-1 medicines may themselves affect how the gallbladder contracts and empties, independent of weight loss. This is an area of ongoing study and the evidence is not settled.

Underlying risk

People living with obesity already have a higher risk of gallstones than the general population. Other established risk factors noted by the NHS include being female, being over 40, and having a family history of gallstones. Many people starting GLP-1 treatment therefore have a higher baseline risk before they take their first dose.

Who might be at higher risk?

Tell your prescriber if any of the following apply. They do not necessarily rule out treatment, but they help your prescriber weigh up the risks and benefits:

• Previous gallstones or biliary colic
• Previous cholecystitis or gallstone pancreatitis
• A family history of gallstones
• A history of very rapid weight loss, including from previous diets
• Liver conditions
• Previous bariatric surgery
• Other medicines known to affect the gallbladder

For a broader view of factors that may affect suitability, see who should not take GLP-1 medicines.

Recognising symptoms

Biliary colic

The NHS describes gallstone pain as sudden, intense pain in the tummy, usually in the upper right side or the centre, just below the ribs. Some people also feel it in the right shoulder or between the shoulder blades. Typical features include:

• Pain that comes on suddenly, often after a meal, especially a fatty one
• Pain that lasts from around 30 minutes to several hours, then eases
• Feeling or being sick during the episode
• Pain that may come and go over weeks or months

Signs of complications

The following suggest a stone may be causing more serious problems and need urgent assessment:

• Pain lasting longer than eight hours
• A high temperature or shivering
• Yellowing of the skin or the whites of the eyes (jaundice)
• Itchy skin
• Dark urine and pale stools
• Feeling very unwell, confused or drowsy
• Severe central pain spreading to the back, which may suggest pancreatitis

Distinguishing gallbladder pain from common GLP-1 side effects

Indigestion, bloating and mild tummy discomfort are common on GLP-1 medicines, particularly after starting or increasing the dose. Our guide to reflux, burping and indigestion on GLP-1 medication covers these. Gallbladder pain tends to differ in being:

• More intense and localised, usually upper right or central
• Episodic and often triggered by meals
• Sometimes felt in the right shoulder or back
• Not relieved by antacids

If you are unsure, it is always reasonable to ask a pharmacist, your prescriber or NHS 111.

Diagnosis and treatment

If your GP or prescriber suspects gallstones, they will usually arrange blood tests to check liver function and an ultrasound scan of the abdomen. NICE guidance on gallstone disease (CG188) recommends liver function tests and ultrasound as first-line investigations for suspected gallstone disease.

Treatment depends on your symptoms:

The NHS notes that people can live normally without a gallbladder. Bile then flows directly from the liver into the intestine. Some people notice looser stools or difficulty with very fatty meals afterwards.

What happens to your GLP-1 treatment?

There is no single rule for gallstones in the way there is for confirmed pancreatitis, where the MHRA and SmPCs are clear that treatment should not be restarted. Whether you continue, pause or stop treatment after gallstones are found is a clinical decision based on:

• How severe your symptoms are
• Whether there are complications
• Whether surgery is planned
• The benefits you are getting from treatment
• Your preferences

If you need surgery, tell the surgical and anaesthetic team that you take a GLP-1 medicine. These medicines slow stomach emptying, which can increase the risk of stomach contents entering the lungs during general anaesthesia or deep sedation. The SmPCs advise that this should be considered before procedures. Our guide to GLP-1 medication, surgery and anaesthesia explains what to expect.

Gallstones, pancreatitis and the 2026 MHRA warning

Gallstones are one of the two most common causes of acute pancreatitis in the UK. In January 2026, the MHRA strengthened warnings about acute pancreatitis across all GLP-1 and dual GLP-1/GIP medicines, highlighting rare necrotising and fatal cases. While the MHRA did not attribute these cases specifically to gallstones, the link between gallbladder disease and pancreatitis is one reason it is important not to ignore gallbladder symptoms.

If you have severe, persistent tummy pain that may spread to the back, stop taking your GLP-1 and seek urgent medical attention. Read more in our guide to GLP-1 medication and pancreatitis.

Can you reduce your risk?

There is no proven way to prevent gallstones on GLP-1 treatment, and research on prevention in this specific setting is limited. However, general principles may help.

Follow the titration plan

Doses are increased gradually, usually every four weeks, to help your body adjust. Increasing faster than prescribed, or using more than your prescribed dose, may speed up weight loss and side effects without proper oversight.

Avoid extreme restriction

GLP-1 medicines reduce appetite substantially, and some people end up eating very little. Very low intakes, long gaps without food and cutting out fat entirely may all contribute to bile stasis. Aim for regular, balanced meals, even if they are small. Our guides on what to eat on GLP-1 medication and protein on GLP-1 medication give practical ideas.

Include some healthy fats

Small amounts of healthy fats, such as olive oil, nuts, seeds, oily fish and avocado, stimulate the gallbladder to contract. Large, greasy meals, however, can trigger pain in people who already have stones.

Eat fibre and stay hydrated

Fibre-rich foods such as wholegrains, vegetables, beans and fruit are part of a healthy diet and support digestion generally. Staying well hydrated also matters, particularly if you have vomiting or diarrhoea.

Stay active

Regular physical activity is linked to better metabolic health and is recommended alongside GLP-1 treatment. See our guide to exercise on GLP-1 medication.

Keep realistic expectations

Faster is not always better. Our guide to realistic weight-loss expectations explains typical patterns of weight loss on treatment.

If you have already had your gallbladder removed

Many people considering GLP-1 treatment have previously had their gallbladder removed, often because of gallstones. A few points are worth knowing:

• Stones cannot form in a gallbladder that is no longer there. The main gallbladder-specific risks discussed in this guide therefore do not apply in the same way.
• Bile duct stones can still occur occasionally. Stones can sometimes form in, or remain in, the bile ducts after surgery. Symptoms such as pain, jaundice, dark urine or fever still need prompt assessment.
• Digestive symptoms may overlap. Some people have looser stools or difficulty with fatty meals after gallbladder removal. GLP-1 medicines can also cause diarrhoea and indigestion, so it may be harder to tell what is causing what. Our guide to diarrhoea on GLP-1 medication may help.
• Tell your prescriber. Previous abdominal surgery is part of the medical history any prescriber should ask about.

Gallbladder symptoms and stopping treatment

Some people wonder whether stopping their GLP-1 will make gallstones go away. Generally, once gallstones have formed they do not dissolve on their own, so stopping the medicine does not remove existing stones. It may reduce the speed of further weight loss, which could reduce the drive for new stone formation, but this is not a reason to stop without advice.

Equally, stopping treatment has its own consequences, including the likelihood of regaining weight over time. Our guide to weight regain after stopping GLP-1 medication explains the evidence. These trade-offs are exactly why decisions should be made with your prescriber rather than alone.

Choosing a prescriber who takes safety seriously

A responsible prescriber, NHS or private, should ask about your gallbladder history, explain the warning signs, and be available if you have symptoms. If you are comparing regulated online services, our provider comparison sets out how each approaches medical screening and follow-up. We do not rank providers, and the decision about treatment always rests with a prescriber.

For more on side effects of individual medicines, read the Mounjaro side effects guide, the page on Mounjaro and gallbladder problems, or the Wegovy side effects guide. Our hub on weight-loss injections gives a broader overview.

Reporting side effects

If you develop gallstones or any other suspected side effect while taking a GLP-1 medicine, you can report it to the MHRA through the Yellow Card scheme, online or via the app. You do not need to be sure the medicine was responsible. Patient and clinician reports help regulators monitor safety and update product information.

When to speak to a professional

Call 999 or go to A&E if you have:

• Severe, persistent abdominal pain, especially if it spreads to your back, with or without vomiting. This may be acute pancreatitis. Stop your GLP-1 and tell staff you take it.
• Upper right tummy pain with a high temperature, shivering or feeling very unwell
• Yellowing of the skin or the whites of the eyes (jaundice), especially with pain or fever
• Confusion or extreme drowsiness
• Vomiting blood or passing black, tarry stools

Call NHS 111 or contact your GP or prescriber urgently if you have:

• Pain in the upper right or centre of your tummy lasting more than a few hours
• Repeated episodes of pain after meals
• Dark urine, pale stools or itchy skin
• Vomiting that stops you keeping fluids down, or signs of dehydration such as dark urine, peeing less or dizziness

Speak to your prescriber before starting or continuing treatment if:

• You have had gallstones, cholecystitis or gallstone pancreatitis before
• You are planning surgery or a procedure under sedation
• You are losing weight much faster than expected

If you are struggling with your mental health or having thoughts of suicide, call NHS 111 (option 2 for mental health in many areas), contact Samaritans free on 116 123, or call 999 in an emergency.