Diarrhoea and Sulphur Burps on Wegovy: Why They Happen and When to Seek Help

Why does Wegovy cause sulphur burps and diarrhoea at the same time?

Wegovy works by activating GLP-1 receptors, which among other effects slows gastric emptying — food leaves your stomach and travels through your intestines more slowly than usual. That slower transit time is useful for appetite control, but it gives gut bacteria more time to ferment food that would normally pass through quickly. The by-product of that fermentation is hydrogen sulphide gas, which is what produces the distinctly unpleasant egg-like smell associated with sulphur burps and, in some cases, flatulence.

Diarrhoea arises through a slightly different mechanism. Semaglutide affects the gut's normal motility patterns, and for some people the colon responds with looser, more urgent stools rather than the constipation that others experience. If you are trying to understand why Wegovy causes sulphur burps and diarrhoea together, both symptoms reflect the same underlying disruption to how your digestive system handles food under semaglutide. The broader side-effect picture for Wegovy is largely gastrointestinal, and these two features sit within that well-documented pattern. According to the NHS medicines page for semaglutide, common GI side effects include nausea, vomiting, diarrhoea, constipation and burping, all traceable to the same mechanism.

Symptoms are typically at their peak during the first four weeks of a new dose. If yours have continued for longer than that at an unchanged dose, it is worth discussing with a prescriber rather than waiting.

What can you eat (and avoid) to reduce sulphur burps and diarrhoea on semaglutide?

Diet has a meaningful effect on both symptoms. Sulphur-rich foods (including eggs, red meat, onions, garlic, cruciferous vegetables like broccoli and Brussels sprouts, and some processed foods containing sulphur preservatives) give gut bacteria more raw material for hydrogen sulphide production. Cutting back temporarily does not mean eliminating these foods permanently; many are nutritionally important on Wegovy, where protein adequacy matters. The goal is to reduce the load during the adjustment period, then reintroduce slowly.

High-fat meals make things worse on both counts. Fat already slows digestion under normal circumstances; combined with semaglutide's effect on gastric emptying, a large fatty meal can produce prolonged bloating, sulphur burping and loose stools in the hours that follow. Smaller, lower-fat meals eaten at regular intervals tend to produce far fewer symptoms. Carbonated drinks and alcohol can add to gas and loose stools and are worth reducing while symptoms persist.

Staying well hydrated is particularly relevant when diarrhoea is frequent. Plain water, diluted squash and oral rehydration salts if stools are very loose all help maintain fluid balance. Some people find keeping a small water bottle in their gym bag as a prompt helps during the first weeks of treatment. Detailed dietary guidance alongside treatment is best discussed with a prescriber or dietitian who knows your full picture. Our page on managing sulphur burps on Wegovy covers practical strategies in more detail.

When do diarrhoea and sulphur burps on Wegovy need medical attention?

Most people experience these symptoms as uncomfortable rather than serious, and they ease as the body adjusts. There are situations, though, where prompt medical contact matters. Severe diarrhoea that causes signs of dehydration (dizziness, dark urine, significantly reduced urination, or feeling faint) needs to be assessed. If you cannot keep fluids down alongside frequent loose stools, contact your GP or call NHS 111.

Severe, persistent stomach pain that radiates to your back, with or without vomiting, should be treated as urgent regardless of whether you also have diarrhoea. The MHRA highlighted acute pancreatitis as a serious but infrequent risk with GLP-1 medicines in a Drug Safety Update issued in January 2026; this symptom pattern is the key warning sign. Seek emergency care if that describes what you are experiencing.

Symptoms that have not improved at all after two to three weeks on the same dose, or that are significantly affecting your daily life, are worth raising with a prescriber rather than simply enduring. Many patients find it helpful to read about how Wegovy sulfur burps typically develop and resolve, which can help distinguish normal adjustment from something that needs clinical attention. You can also report symptoms via the MHRA's Yellow Card scheme, which helps monitor the safety profile of all medicines including Wegovy. Our contact page explains how to reach the aftercare team if you are already a patient with us.

Does this mean Wegovy is not suitable for you?

Not necessarily. These side effects are common and most people who experience a sulfur burp on Wegovy do not stop treatment because of them. The clinical picture matters: how severe the symptoms are, how long they have lasted, whether dietary changes make a dent, and what other factors are present. A prescriber weighs all of that alongside the potential benefit of continued treatment.

If you are thinking about starting Wegovy, or you are already taking it and finding these symptoms difficult, the right place to have that conversation is with a clinician who knows your history. The Wegovy treatment overview covers eligibility and the clinical process in full. At nume, our prescribers discuss side effects, individual suitability and management strategies as part of every consultation, not as an afterthought. If you are exploring your options, starting a free consultation puts those questions in front of a GPhC-registered prescriber the same day.