Is pancreatitis more common with retatrutide than with tirzepatide?

Nobody knows yet. The Phase 2 trials had only 3 cases among 457 retatrutide patients, which is too few to compare. The TRIUMPH-5 head-to-head trial and the full Phase 3 safety tables should give a better answer.

Should I get my lipase checked before a trial?

Trial protocols set their own lab schedules, and study staff decide what to test. Outside a trial, a raised lipase without symptoms has unclear meaning, according to the Zepbound label. Tell the study team about any past pancreatitis or gallstones.

Can people with a past history of pancreatitis join retatrutide trials?

Generally not. The TRIUMPH-1 registry entry on ClinicalTrials.gov lists "have had pancreatitis" as an exclusion. That also means the Phase 3 results say little about people with a past episode.

Does losing weight slowly lower the gallstone risk?

The NIDDK says diets and surgeries that cause fast weight loss are more likely to lead to gallstone problems than slower approaches. It also warns against repeated loss and regain. Whether a slower dose escalation lowers the risk with retatrutide has not been tested.

I had my gallbladder removed. Does the gallstone risk still apply?

Gallstones form in the gallbladder, so removing it takes away most of that specific risk. Stones can still form in the bile ducts in some people. Pancreatitis risk from other causes remains, so the urgent symptoms still matter.

Does Retatrutide Cause Pancreatitis or Gallstones?

The short answer: Possibly, but the data are thin. In the two Phase 2 trials, a handful of people on retatrutide had acute pancreatitis or gallbladder inflammation, and none on placebo did. The numbers are too small to set a real rate. The large Phase 3 results released so far do not report pancreatitis or gallbladder counts, so treat both as plausible risks shared with the GLP-1 drug class.

Retatrutide is still investigational. No FDA label exists yet, so there is no official warning section to read. What we have is trial registry data, published abstracts, and the labels of related approved drugs. For the full side-effect picture, including nausea and dysesthesia, see our retatrutide side effects guide. This page covers only the pancreas and the gallbladder.

What did the Phase 2 trials report for pancreatitis and gallbladder events?

Two Phase 2 trials have posted full adverse event tables on ClinicalTrials.gov. Here is what they list as serious events.

Obesity trial (Jastreboff et al., NEJM 2023). Of 267 people on any retatrutide dose, 1 had serious acute pancreatitis (in the 12 mg group). One more had serious acute cholecystitis, a gallbladder inflammation (in an 8 mg group). The 70 people on placebo had neither (NCT04881760 results).
Type 2 diabetes trial (Rosenstock et al., Lancet 2023). Of 190 people on retatrutide, 2 had serious acute pancreatitis. One was in the lowest 0.5 mg group and one in an 8 mg group. One person in another 8 mg group had serious chronic cholecystitis. None of the 45 placebo or 46 dulaglutide patients had these events (NCT04867785 results).

Across both trials, that adds up to 3 pancreatitis cases and 2 gallbladder inflammation cases in 457 people on retatrutide. Two cautions apply. First, these are single cases, so they cannot show a dose pattern or a true rate. One pancreatitis case came at the smallest dose. Second, the registry lists non-serious events only when they reach 5% in at least one group. Mild gallstones that never became serious may not appear at all. The registry lists no separate gallstone (cholelithiasis) entry for either trial.

What about rising lipase and amylase levels?

Lipase and amylase are pancreatic enzymes. Doctors measure them in the blood when they suspect pancreatitis. Drugs in this class often raise them a little without causing disease.

In the Phase 2 obesity trial, "lipase increased" was reported as an adverse event in 15 of 267 retatrutide patients (about 5.6%) versus 2 of 70 on placebo (about 2.9%). The 12 mg group had the most, at 5 of 62. "Amylase increased" was reported in 5 retatrutide patients and 2 on placebo (NCT04881760). In the diabetes trial, lipase increases were reported in 10 of 190 retatrutide patients, 2 of 45 on placebo, and 1 of 46 on dulaglutide (NCT04867785).

The Zepbound label gives useful context. Tirzepatide raised mean lipase by 28% to 35% and pancreatic amylase by 20% to 25% from baseline. The label states that "the clinical significance of elevations in amylase or lipase" is "unknown in the absence of other signs and symptoms of pancreatitis" (Zepbound label, DailyMed). A raised enzyme alone is not a diagnosis.

What do the Phase 3 TRIUMPH trials say so far?

The Phase 3 data are bigger but less detailed on these two risks. TRIUMPH-1 randomized 2,339 adults with obesity and ran for 80 weeks. Its published abstract says only that "the most common adverse events were gastrointestinal" (Jastreboff et al., NEJM 2026).

Lilly's TRIUMPH-1 poster from the June 2026 ADA meeting reported serious adverse events in 7.7% to 10.5% of retatrutide groups versus 5.5% on placebo. Its listed adverse events of special interest were dysesthesia, injection site reactions, gut events, and low blood pressure (Lilly ADA 2026 poster). The poster pages we could read did not give pancreatitis or gallbladder counts.

The September 29, 2026 TRIUMPH-2 release, for people with type 2 diabetes, listed diarrhea, nausea, constipation, decreased appetite, and vomiting as the most common events. It also reported dysesthesia and urinary tract infections. It did not mention pancreatitis or gallbladder events for retatrutide (Eli Lilly, September 29, 2026). Full safety tables should come with the peer-reviewed papers and the FDA review. Lilly plans to file in the first quarter of 2027.

What do labels for approved drugs in this class warn?

Retatrutide acts on the same GLP-1 and GIP receptors as tirzepatide, plus the glucagon receptor. So the approved labels are the best guide to what regulators will likely look for.

The Zepbound label warns that "acute pancreatitis, including fatal and non-fatal hemorrhagic or necrotizing pancreatitis, has been observed" with GLP-1 drugs and tirzepatide. In its two main weight trials, adjudicated acute pancreatitis occurred in 0.2% of both the tirzepatide and placebo groups (Zepbound label).

The gallbladder signal is clearer. The label says treatment "is associated with an increased occurrence of acute gallbladder disease." In the same trials, cholelithiasis occurred in 1.1% on tirzepatide versus 1% on placebo. Cholecystitis occurred in 0.7% versus 0.2%. The label adds that "acute gallbladder events were associated with weight reduction." Readers on tirzepatide can find more on mounjaro.md.

Why does fast weight loss raise gallstone risk?

Retatrutide causes large weight loss. In TRIUMPH-1, the 12 mg group lost 25.0% of body weight at 80 weeks (NEJM 2026). Our page on how much weight people lose on retatrutide covers those numbers.

The NIDDK explains the link to gallstones. When you lose weight quickly, "your liver releases extra cholesterol into the bile." Fast weight loss "can also prevent the gallbladder from emptying properly." Obesity itself raises gallstone risk, and so does weight cycling (NIDDK). This is why gallstones show up after bariatric surgery and very low-calorie diets, not only with drugs.

The NIDDK also notes that gallstones are the most common cause of acute pancreatitis (NIDDK, pancreatitis). So the two risks can be linked. A gallstone can block a duct and inflame the pancreas.

Which symptoms need urgent care?

Gut side effects are common on drugs in this class, so it helps to know what is different. Seek care right away for:

Severe or persistent pain in the upper abdomen, especially pain that spreads to the back. This is the main sign of acute pancreatitis (NIDDK).
Pain in the upper right abdomen that lasts several hours, often after a heavy meal (NIDDK, gallstones).
Fever or chills with abdominal pain.
Yellow skin or eyes (jaundice), tea-colored urine, or light or clay-colored stools.
Nausea and vomiting together with any of the above, or a fast heartbeat.

Trial participants should call their study site. Anyone using gray-market product has no study team watching for these signs. The FDA says retatrutide has "not been found safe and effective for any condition" and cannot be legally compounded (FDA). See our page on gray-market retatrutide for the added risks.

The bottom line

Retatrutide probably shares the pancreas and gallbladder risks of the GLP-1 class. Phase 2 trials logged 3 pancreatitis cases and 2 gallbladder inflammation cases among 457 treated people, with none on placebo. That is a signal to watch, not a measured rate. Phase 3 safety tables on these events have not been made public yet. Know the warning signs: severe upper abdominal pain, pain into the back, fever, or jaundice.

Last updated: October 2026. This article is for informational purposes only and does not constitute medical advice. Retatrutide is an investigational drug; talk with a clinician about abdominal pain or gallbladder history before any weight-loss treatment.