Mounjaro® and gallbladder problems

Where the warning sits

Section 5.8 of the US label opens with a statement about the drug class: acute gallbladder events such as gallstones and gallbladder inflammation have been reported in trials of GLP-1 receptor agonists and after approval ^[1]. It then gives Mounjaro®’s own figure and asks for gallbladder tests and appropriate follow-up when gallstones are suspected ^[1]. Canada’s monograph gives the same 0.6% against 0%, but names the counted events as acute cholecystitis, biliary colic and gallbladder removal ^[4].

The European information places gallstones (cholelithiasis) and gallbladder inflammation (cholecystitis) in its “uncommon” band, meaning up to 1 person in 100 ^[3]. None of the three documents gives a gallbladder figure for the pediatric trial or the SURPASS-CVOT heart trial.

The figures, including weight-management trials

The US number comes from SURPASS-1 and SURPASS-5, in which 718 adults with type 2 diabetes took Mounjaro® for an average of 36.6 weeks and 235 took placebo; it is one combined figure for all doses ^[1]. The European information adds three settings in which tirzepatide is authorised under the Mounjaro® name in the EU, with longer trials and different populations ^[3].

What the counted terms mean

• Cholelithiasis: gallstones, hard pebble-like deposits, usually of cholesterol or bilirubin, that form in the gallbladder ^[8].
• Biliary colic: sudden pain, usually in the upper right belly, when a gallstone blocks a bile duct for a while; NIH also calls this a gallbladder attack ^[8].
• Cholecystitis: inflammation of the gallbladder, one of the complications of gallstones ^[8].
• Cholecystectomy: an operation to remove the gallbladder, most often done through small cuts ^[11].

Is it linked to weight loss?

What the labels say: the US label does not give a reason for its finding ^[1]. The European information does draw a link: in its weight-management trials, acute gallbladder events were positively associated with weight reduction ^[3].

What the NIH explains: having obesity raises the chance of gallstones, but so does losing weight quickly. When weight falls fast, the liver releases extra cholesterol into bile, and the gallbladder may not empty properly ^[10]. Diabetes and insulin resistance are risk factors in their own right ^[8].

What is not known: whether tirzepatide affects the gallbladder in other ways, beyond weight loss, has not been shown in the product information we read. It is plausible that both the starting risk of the people treated and the speed of weight loss play a part.

What reviews and real-world data show

A 2023 meta-analysis of nine randomised trials with 9,871 participants found the combined outcome of gallbladder or bile duct disease more common with tirzepatide than with placebo or basal insulin (risk ratio 1.97), while gallstones, cholecystitis and bile duct disease on their own did not reach significance ^[5]. A 2025 meta-analysis of 12 trials with 12,351 people found tirzepatide associated with gallbladder or bile duct disease (risk ratio 1.52) and with gallstones (1.67), with no dose-response between 5, 10 and 15 mg ^[6].

In a large US cohort of adults with type 2 diabetes, a combined outcome of serious stomach and bowel events that included gallbladder disease occurred at similar rates on tirzepatide, semaglutide and dulaglutide ^[7]. Observational data cannot rule out every difference between groups, but it suggests tirzepatide is broadly in line with its class.

Symptoms to report

The Medication Guide asks you to tell your healthcare provider right away about pain in the upper stomach, yellowing of the skin or eyes, fever, or clay-coloured stools ^[2]. Canada’s patient information adds that symptoms can start suddenly, with intensifying pain in the abdomen, between the shoulder blades or in the right shoulder, and asks for immediate medical attention for severe abdominal pain, yellow skin or high fever with chills ^[4].

MedlinePlus describes the typical pain as lasting at least 30 minutes in the right or middle upper abdomen, constant or cramping, sharp or dull, sometimes with nausea and vomiting ^[11]. The NIH says many gallstones cause no symptoms at all; these silent stones usually do not need treatment ^[8][9].

Telling it apart from other stomach pain

Stomach pain on its own is common on Mounjaro®: in the same diabetes trials it was reported by 5% to 6% on the medicine against 4% on placebo ^[1]. What moves pain into the warning category is its severity and duration and what comes with it, such as fever, yellowing or a change in stool or urine colour. The NIH notes that gallstone symptoms can resemble appendicitis, ulcers, pancreatitis and reflux, and that a gallstone blocking the pancreatic duct can itself cause pancreatitis ^[8][9].

Severe, persistent pain that reaches the back is the pattern the label describes for pancreatitis, a reason to stop Mounjaro® and call your provider at once ^[1][2]. Sorting one cause from another is a clinical task, often starting with an abdominal ultrasound and blood tests, according to MedlinePlus ^[11].

Who is more likely to develop gallstones

The NIH and MedlinePlus list women, people over 40, a family history of gallstones, obesity, diabetes and insulin resistance, high triglycerides, rapid weight loss, pregnancy, and birth control pills or hormone therapy among risk factors ^[8][11]. If several apply to you, mention any past gallbladder trouble to your prescriber. The NIH also advises against crash diets and repeated cycles of losing and regaining weight ^[10]. Whether your pace of weight loss on tirzepatide is appropriate is your prescriber’s call.

Mounjaro® is a registered trademark of Eli Lilly and Company. PepLabo is not affiliated with or endorsed by Eli Lilly and Company.