Does Wegovy cause gallstones? Wegovy (semaglutide 2.4 mg), a GLP-1 receptor agonist approved for chronic weight management, is associated with an increased risk of gallstone formation. Clinical trials show gallstones occur in approximately 1.6–2.6% of Wegovy users compared with 0.7% on placebo—a two- to three-fold relative increase. This risk stems primarily from rapid weight loss, which alters bile composition and reduces gallbladder motility, creating conditions favourable for cholesterol crystallisation. While the absolute risk remains low, understanding symptoms, preventive strategies, and when to seek medical advice helps patients and clinicians manage this recognised complication effectively whilst benefiting from significant weight reduction.
Quick Answer: Wegovy increases gallstone risk approximately two- to three-fold compared with placebo, with clinical trials reporting gallstones in 1.6–2.6% of users versus 0.7% on placebo.
Wegovy (semaglutide 2.4 mg) is a glucagon-like peptide-1 (GLP-1) receptor agonist approved in the UK for chronic weight management in adults with obesity or overweight with weight-related comorbidities. While Wegovy has demonstrated significant efficacy in promoting weight loss, patients and healthcare professionals should be aware of an increased risk of gallstone formation during treatment.
The relationship between Wegovy and gallstones appears to be primarily related to weight loss, though there may also be direct effects on gallbladder function. Semaglutide works by mimicking the natural hormone GLP-1, which regulates appetite, slows gastric emptying, and enhances insulin secretion. These mechanisms lead to reduced caloric intake and substantial weight loss—typically 12–15% of body weight over 68 weeks in clinical trials, as demonstrated in the STEP (Semaglutide Treatment Effect in People with obesity) programme.
Rapid and significant weight loss creates favourable conditions for gallstone development. This phenomenon is well documented across all forms of rapid weight reduction, including bariatric surgery, very low-calorie diets, and other weight-loss medications. The gallbladder’s altered bile composition and reduced contractility during periods of rapid weight loss increase the likelihood of cholesterol crystallisation and stone formation. Additionally, GLP-1 receptor agonists may directly reduce gallbladder motility, potentially contributing to gallstone risk.
According to the Wegovy Summary of Product Characteristics (SmPC) and EMA assessment report, gallstones (cholelithiasis) and inflammation of the gallbladder (cholecystitis) are recognised adverse reactions. While gallstones represent a manageable complication, they should be balanced against the substantial metabolic and health benefits of achieving weight loss in individuals with obesity. Awareness and appropriate monitoring allow early identification and timely management.
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Start HereThe physiological changes that occur during rapid weight loss create an environment conducive to gallstone formation through several interconnected mechanisms.
Altered bile composition is a primary factor. During rapid weight loss, the liver secretes increased amounts of cholesterol into bile while simultaneously reducing bile acid and phospholipid secretion. This imbalance creates cholesterol-supersaturated bile, where cholesterol concentration exceeds the bile’s capacity to keep it dissolved. When cholesterol precipitates out of solution, it forms crystals that can aggregate into stones.
Reduced gallbladder motility compounds the problem. The gallbladder normally contracts regularly in response to meals, expelling bile into the small intestine. During caloric restriction and reduced fat intake—common with Wegovy treatment—the gallbladder contracts less frequently. This biliary stasis allows cholesterol crystals more time to aggregate and grow into clinically significant stones.
Additionally, increased mobilisation of cholesterol from adipose tissue during fat breakdown raises circulating cholesterol, which the liver then secretes into bile, further increasing saturation.
The risk appears to be time-dependent and related to the rate of weight loss. Most gallstones develop during periods of active weight loss. Individuals losing weight more gradually face lower risk, though susceptibility varies based on genetic factors, baseline gallbladder function, and dietary composition.
GLP-1 receptor agonists such as semaglutide may also directly reduce gallbladder motility independent of weight loss, contributing to the overall risk profile.
Clinical trial data provide insight into the incidence of gallbladder-related complications in patients treated with Wegovy. The STEP clinical trial programme, which included over 4,500 participants, systematically recorded gallbladder events.
In the pivotal STEP 1 trial, cholelithiasis (gallstones) occurred in 1.6% of participants receiving Wegovy compared with 0.7% receiving placebo over 68 weeks. Cholecystitis (gallbladder inflammation) was reported in 0.6% of Wegovy-treated versus 0.2% of placebo participants—a statistically significant difference.
The STEP 3 trial, which combined semaglutide with intensive behavioural therapy, showed similar findings, with cholelithiasis reported in 2.6% of semaglutide participants. Some cases required medical intervention, including cholecystectomy (gallbladder removal).
Across the STEP programme, gallbladder disorders were more common in Wegovy users, representing a two- to three-fold relative risk increase consistent with other rapid weight-loss interventions.
Regulators including the MHRA and EMA list cholelithiasis and cholecystitis in the product information as adverse reactions. The absolute risk remains low, and the benefits of weight loss—including reduced cardiovascular risk and improved metabolic health—generally outweigh gallstone risk for most patients. Nevertheless, clinicians should assess risk individually, especially in those with pre-existing gallbladder disease.
Early recognition of gallstone symptoms is essential for Wegovy users. Prompt diagnosis and management prevent complications such as acute cholecystitis, cholangitis, or pancreatitis.
Typical symptoms (biliary colic) include:
Sudden, severe pain in the right upper abdomen, often radiating to the shoulder blade or back.
Pain lasting 30 minutes to several hours, often after fatty meals.
Nausea and vomiting during pain episodes.
Pain that may wake you from sleep a few hours after eating.
The pain occurs when a gallstone temporarily blocks the cystic duct, causing the gallbladder to contract forcefully against the obstruction.
Warning signs of acute cholecystitis (urgent medical review required):
Persistent right-sided abdominal pain lasting more than six hours.
Fever and chills.
Jaundice (yellowing of the skin or eyes).
Severe tenderness when pressing the right upper abdomen during deep breathing.
Some symptoms such as bloating, indigestion, or intolerance to fatty foods may overlap with Wegovy’s gastrointestinal side effects. However, new, worsening, or localised right-upper-quadrant pain should always be assessed clinically. Many gallstones remain silent and are found incidentally on imaging; these do not require treatment unless symptomatic.
While gallstone risk cannot be completely eliminated, several strategies can reduce likelihood during Wegovy treatment.
Gradual, sustainable weight loss is protective. Avoid excessively rapid weight loss by following the standard 16-week titration schedule (0.25 mg weekly, gradually increasing to 2.4 mg). This approach improves tolerability and moderates gallstone risk.
Maintain adequate dietary fat intake. Consuming moderate amounts of healthy fats (e.g. olive oil, avocados, nuts, seeds, oily fish) encourages gallbladder contraction and prevents biliary stasis. Very low-fat diets can paradoxically increase gallstone risk.
Eat regular meals. Structured meal patterns (three balanced meals daily) promote consistent bile flow and gallbladder emptying.
Stay well hydrated. The NHS recommends 6–8 cups of fluid daily, adjusting for climate and activity.
Ursodeoxycholic acid (UDCA) may be prescribed off-label in specific high-risk cases (for example, prior gallstones, family history, or gallbladder sludge). It should only be initiated under specialist supervision. Routine preventive use is not recommended for all patients on GLP-1 receptor agonists.
Preventive strategies should be individualised through shared decision-making with healthcare professionals.
Seek urgent medical attention (call 999 or go to A&E) if you experience:
Severe, persistent abdominal pain lasting more than six hours, especially in the right upper quadrant.
High fever (temperature above 38.5 °C) with abdominal pain.
Jaundice (yellowing of the skin or eyes).
Severe vomiting preventing fluid or medication intake.
Symptoms of pancreatitis: severe upper-abdominal pain radiating to the back with vomiting.
These may indicate acute cholecystitis, cholangitis, or gallstone pancreatitis, which require hospital evaluation.
Contact your GP within 24 hours if you notice:
Recurrent right-sided abdominal pain that resolves then recurs.
New intolerance to fatty foods or persistent indigestion.
Clay-coloured stools or dark urine (possible bile obstruction).
Unexplained generalised itching.
Your GP may arrange abdominal ultrasound, the gold-standard test for detecting gallstones and assessing gallbladder inflammation. Early imaging supports accurate diagnosis and management. If acute cholecystitis is confirmed, early surgical removal (cholecystectomy) may be advised following national guidelines.
While Wegovy slightly increases gallstone risk, most patients complete treatment without gallbladder complications. Ongoing communication with your healthcare team ensures early recognition and effective management, maximising both safety and treatment success.
Clinical trials show gallstones occur in approximately 1.6–2.6% of Wegovy users compared with 0.7% on placebo over 68 weeks, representing a two- to three-fold relative risk increase. The absolute risk remains low, and most patients complete treatment without gallbladder complications.
Typical symptoms include sudden severe pain in the right upper abdomen radiating to the shoulder blade, nausea, and vomiting after meals. Seek urgent medical attention for persistent pain lasting over six hours, fever, jaundice, or severe vomiting, as these may indicate acute cholecystitis or other complications.
Risk reduction strategies include following the gradual 16-week titration schedule, maintaining moderate healthy fat intake to promote gallbladder contraction, eating regular structured meals, and staying well hydrated. Ursodeoxycholic acid may be considered in high-risk cases under specialist supervision, though routine preventive use is not recommended.
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