Acute pancreatitis and gallstone-related problems are recognised but uncommon risks of GLP-1 medicines such as Mounjaro, Wegovy and Foundayo. The key warning sign of pancreatitis is severe, persistent pain in the upper stomach that may spread to your back, with or without vomiting. Gallbladder trouble typically causes pain in the upper right or middle abdomen, often after a fatty meal, and may come with fever or yellowing of the skin or eyes. If you have severe, persistent abdominal pain, do not take your next dose and seek urgent medical advice. If pancreatitis is confirmed, the medicine should not be restarted.
Nausea, bloating, wind, indigestion, loose stools and constipation are very common on Mounjaro, Wegovy and Foundayo, particularly when you start or increase your dose. They are uncomfortable but not dangerous. The question to ask yourself is whether your symptom is mild and passing, or severe, constant and getting worse. The second pattern is the one that needs medical attention. Our guides on nausea and constipation cover the everyday symptoms, and the Mounjaro, Wegovy and Foundayo side effects guides explain what to expect.
| Usually an expected side effect | More likely a warning sign |
|---|---|
| Mild to moderate nausea that comes and goes | Severe, constant pain in the upper abdomen |
| Bloating, wind and burping after meals | Pain that spreads through to the back |
| Loose stools or constipation | Repeated vomiting alongside severe pain |
| Mild stomach discomfort that settles in hours or days | Pain that lasts for hours without easing |
| Symptoms related to a recent dose increase | Fever, a swollen or tender abdomen, or yellowing of the skin or eyes |
The pancreas is a gland behind the stomach that makes digestive enzymes and hormones, including insulin. Acute pancreatitis is sudden inflammation of the pancreas. It is often caused by gallstones or heavy alcohol intake, and can also be caused by certain medicines, high levels of fats (triglycerides) in the blood, or other conditions. It can range from mild to severe and needs prompt medical assessment.
What the UK product information says
- Acute pancreatitis has been reported with GLP-1 based medicines and is listed as an uncommon side effect.
- In the Wegovy trials, acute pancreatitis was reported in about 0.2% of people at the 2.4mg dose.
- These medicines have not been studied in people with a history of pancreatitis and should be used with caution in them.
- If pancreatitis is suspected, the medicine should be stopped. If it is confirmed, the medicine should not be restarted.
- Raised pancreatic enzymes on a blood test, without symptoms, do not by themselves predict acute pancreatitis.
Symptoms of pancreatitis
- Severe pain in the upper stomach area that does not go away and may spread to your back
- Pain that may be worse after eating, or when lying flat
- Nausea and vomiting, sometimes repeated
- A swollen or tender abdomen
- Fever or a fast heartbeat
Act immediately
If you have severe, persistent stomach pain, especially if it spreads to your back or comes with vomiting, do not take your next dose. Seek urgent medical advice by calling 111 or going to A&E, and call 999 if the pain is severe or you feel very unwell. Tell the clinician you take a GLP-1 medicine.
The gallbladder is a small organ under the liver that stores bile, which helps digest fat. Gallstones can form when bile contains too much cholesterol or when the gallbladder does not empty well. They are common in the general population. Rapid weight loss is a recognised risk factor for gallstones, and the UK product information for Mounjaro notes that, in the weight management studies, acute gallbladder events were positively correlated with weight reduction. In other words, the more weight lost, the more likely gallbladder events were. Our guides on {a('w_plateau','Wegovy plateaus')} and {a('m_plateau','Mounjaro plateaus')} and on {a('wl','weight loss support')} cover pace and expectations.
| Condition | What it is | Frequency in UK product information |
|---|---|---|
| Gallstones (cholelithiasis) | Stones in the gallbladder, which may cause pain or no symptoms | Common with these medicines |
| Cholecystitis | Inflammation of the gallbladder, often caused by a stone blocking the outlet | Reported, more often in some trials |
| Acute pancreatitis | Sudden inflammation of the pancreas, sometimes caused by gallstones | Uncommon |
In the Wegovy 2.4mg trials, gallstones were reported in about 1.6% of people. Many gallstones cause no symptoms and are never noticed.
Symptoms of gallbladder problems
- Pain in the upper right or middle abdomen, sometimes spreading to the right shoulder or back
- Pain that often starts after a fatty meal and can last from 30 minutes to several hours
- Nausea and vomiting
- Fever or chills, which may suggest infection or inflammation
- Yellowing of the skin or the whites of the eyes (jaundice), pale stools or dark urine
Get medical advice
Pain in the upper right abdomen that lasts more than a few hours, or is accompanied by fever, yellowing of the skin or eyes, or repeated vomiting, needs medical assessment the same day. Call 111 or seek urgent care. If you are very unwell, call 999.
| Feature | Ordinary digestive side effect | Possible pancreatitis | Possible gallbladder problem |
|---|---|---|---|
| Location | General stomach area | Upper abdomen, may reach the back | Upper right or middle, may reach right shoulder |
| Severity | Mild to moderate | Severe | Moderate to severe |
| Duration | Hours to days, comes and goes | Constant and persistent | Episodes lasting 30 minutes to hours |
| Triggers | Large or rich meals, dose increase | Alcohol, fatty meals, can occur without | Fatty meals |
| Other signs | Bloating, wind, loose stools | Vomiting, fever, tender abdomen | Fever, jaundice, vomiting |
This table is a guide, not a diagnosis. When in doubt, particularly if pain is severe, get checked. It is always better to be assessed and reassured than to wait. For everyday symptoms, see our Mounjaro tolerability, Wegovy tolerability and Foundayo side effects guides, the Mounjaro, Wegovy and Foundayo dose schedules, and the Wegovy pill guide. Compare options in Mounjaro vs Wegovy.
Anyone can develop gallstones or pancreatitis, but some factors raise the risk. Tell your prescriber about any of these in your consultation. Our Foundayo eligibility guide, the guide to who should not take these medicines and the NHS criteria explain how suitability is assessed.
- A previous episode of pancreatitis, which means the medicine needs particular caution
- A history of gallstones or gallbladder disease
- Heavy alcohol use
- High blood triglycerides or other blood fat disorders
- Rapid weight loss, which increases gallstone risk
- Being female, over 40, or having a family history of gallstones, which are general risk factors for gallstones
- Certain other medicines or medical conditions your clinician will consider
You cannot remove the risk entirely, but you can reduce it.
- Lose weight at a steady pace and avoid very low calorie diets, which raise gallstone risk. See our nutrition guide and calorie deficit calculator.
- Keep alcohol within recommended limits, because heavy drinking is a major cause of pancreatitis. See our alcohol guides for Mounjaro, Wegovy and Foundayo.
- Eat a balanced diet that is not extremely low in fat, because very low-fat diets can reduce gallbladder emptying.
- Tell your prescriber about any history of pancreatitis, gallstones or high triglycerides before starting.
- Do not ignore symptoms that are severe or persistent, and do not dismiss them as “just the medicine”.
| Situation | What to do |
|---|---|
| Severe, persistent abdominal pain, especially spreading to your back, with or without vomiting | Urgent Do not take your next dose. Call 111 or go to A&E; call 999 if very unwell |
| Upper right abdominal pain lasting more than a few hours, with fever or jaundice | Same day Seek same-day medical advice; call 111 or go to urgent care |
| Repeated vomiting and unable to keep fluids down | Urgent Seek urgent advice, as dehydration can affect your kidneys |
| Mild, passing stomach discomfort after a dose increase | Self-help Follow the self-help advice in our digestive guides and speak to your pharmacist if it persists |
| You have been told you had pancreatitis | Prescriber Do not restart the medicine. Tell your prescriber and GP |
If pancreatitis is confirmed, the UK product information says the medicine should not be restarted, and your doctors will advise on the next steps for managing your weight. If you are diagnosed with gallstones or cholecystitis, speak to your prescriber, because treatment may involve your hospital team and the decision to continue the medicine depends on your situation. Never restart a medicine after one of these diagnoses without clinical advice. If you are thinking about stopping for other reasons, see our guide on what happens when you stop Mounjaro, Wegovy or Foundayo, and if you are having an operation such as gallbladder removal, our guide on having surgery on Mounjaro, Wegovy or Foundayo explains what to tell your team.
Reporting Side EffectsRelated reading: microdosing, obesity as a chronic disease, spotting fake weight loss medicines and about Happy Pharmacy. You can report suspected side effects through the MHRA Yellow Card scheme, which helps monitor the safety of medicines. You or a healthcare professional can do this, and reports help build a picture of how often side effects occur.
Questions to Ask Your Prescriber or Pharmacist- Do I have any risk factors for pancreatitis or gallstones?
- What should I do if I have severe stomach pain?
- Is my rate of weight loss appropriate?
- Should I have my blood fats checked?
The bottom line
Most digestive symptoms on a GLP-1 medicine are mild and settle. Severe, persistent abdominal pain, especially spreading to the back, or pain with fever, vomiting or yellowing of the skin, needs urgent medical help. Do not take your next dose, and if pancreatitis is confirmed the medicine should not be restarted. For eligibility and safety questions, start with our weight loss consultation or browse the full guide library. Not sure a pharmacy is genuine? See Is Happy Pharmacy a genuine UK pharmacy?
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Start Your Free Online Consultation → Use code SWITCH10 if you're switching from another provider Happy Pharmacy is a GPhC-registered pharmacy (No. 9013192) — Superintendent Pharmacist: Palvinder Deol — Rated 4.8★ Excellent on Trustpilot- Mounjaro® (tirzepatide) KwikPen: UK Summary of Product Characteristics, sections 4.4 and 4.8 (acute pancreatitis, gallbladder disorders), electronic Medicines Compendium (emc).
- Wegovy® (semaglutide) FlexTouch: UK Summary of Product Characteristics, sections 4.4 and 4.8, emc.
- Foundayo® (orforglipron) UK Summary of Product Characteristics, emc.
- Wilding JPH, et al. Once-weekly semaglutide in adults with overweight or obesity (STEP 1). N Engl J Med. 2021;384:989-1002.
- Jastreboff AM, et al. Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1). N Engl J Med. 2022;387:205-216.
- NHS. Pancreatitis and gallstones: symptoms and when to get help.
- MHRA. Yellow Card scheme: reporting suspected side effects.