Definition
Gallstones (cholelithiasis) are hard, pebble-like pieces, usually of cholesterol or bilirubin, that form in the gallbladder. Most cause no symptoms. Substantial or rapid weight loss raises the risk, and GLP-1 labels report more gallstones on the drug than on placebo.
The gallbladder stores bile and squeezes it into the gut when you eat. Stones form when bile holds too much cholesterol or bilirubin or too few bile salts, or when the gallbladder does not empty fully or often enough. The NIDDK lists obesity and certain kinds of dieting as risk factors. Silent stones usually need no treatment. When a stone blocks a bile duct, it causes a gallbladder attack: pain in the upper right belly, sometimes lasting several hours, often after a heavy meal and in the evening or at night.
In the Wegovy label, gallstones were reported by 1.6% of adults on the injection vs 0.7% on placebo, and by 2.5% on the tablets vs 1%; gallbladder inflammation (cholecystitis) by 0.6% vs 0.2%. The label adds that rapid weight loss raises the risk, but the rate was higher on Wegovy even after accounting for weight loss. In the Zepbound label, gallstones were 1.1% vs 1%, and cholecystitis 0.7% vs 0.2%.
See a doctor right away for belly pain lasting several hours, vomiting, fever or chills, yellow skin or eyes, tea-colored urine or light-colored stools. Stones can also cause pancreatitis. At GLP-1 SOS, a pain like this is never something to manage at home.
In the Lab
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- Gas and burping on a GLP-1: normal or a problem?
- Is it normal to feel nauseous on a GLP-1?
From the people behind the Lab
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GLP-1 SOS is the daily companion made for life on a GLP-1. Plain answers like this one, a support team that replies to real questions from real people, and daily formulas like GLP-1 SOS Daily Gut Relief, designed around the side effects that come with the medication. The GLP-1 Lab is our free education arm: no login, no paywall, no hype. Side effects are part of the road. Suffering through them is not.
Sources (4)
- Definition & Facts for Gallstones. NIH National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).
- Symptoms & Causes of Gallstones. NIH National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).
- Wegovy (semaglutide) injection and tablets, Prescribing Information. Novo Nordisk / FDA, revised June 2026.
- Zepbound (tirzepatide) injection, Prescribing Information. Eli Lilly, revised August 2026.
Reviewed by the GLP-1 SOS editorial team · Education, not medical advice · Talk to your prescriber about your dose and your symptoms.
