Wegovy and Egg Burps: What's Causing That Sulphur Smell

It started the morning after your second pen, here's the biology behind it

Picture this: you've been on Wegovy for a few weeks, feeling pretty good about the reduced appetite, and then one morning you notice your burps smell like overcooked eggs. It's one of those side effects nobody warns you about in the headlines. The reason it happens comes down to one of the ways semaglutide works.

As a GLP-1 receptor agonist, semaglutide slows gastric emptying, the rate at which your stomach pushes food into the small intestine. That's partly why appetite falls so effectively on Wegovy. The trade-off is that food sits in the stomach longer, and bacteria in the gut have more time to ferment it. Proteins breaking down during that extended process release hydrogen sulphide gas, which is responsible for the sulphur or rotten-egg smell. The broader range of Wegovy side effects all trace back to this same gastric-motility effect, nausea, constipation, diarrhoea and burping are the most commonly reported, as noted in the NHS's patient information on semaglutide.

The smell is worse than the substance. Hydrogen sulphide is produced in tiny quantities and the burps themselves are harmless, but they can catch you off guard at inconvenient moments. Knowing the cause helps take some of the alarm out of it.

When egg burps on Wegovy tend to arrive, and when they leave

Timing follows a fairly predictable pattern. Most people who report eggy burps on Wegovy notice them in the 24 to 72 hours after starting a new pen or moving to a higher dose. The stomach is adjusting to a slower pace, fermentation peaks, and then (usually within a week or two) things settle. The burping doesn't disappear for everyone, but the intensity typically drops once your digestive system acclimates to that dose level.

That's also why a dose increase can bring the egg burps back even if they'd faded. Each step up the titration ladder is a fresh adjustment for the gut. If you've been managing well at 1mg and jump to 1.7mg, a brief return of sulphur-scented burping is a common experience, Wegovy-related burping generally tends to follow the same dose-linked rhythm. Your prescriber is the right person to speak to if symptoms feel out of proportion or show no sign of easing after two weeks at a stable dose.

For people who find the egg burps particularly disruptive, it's worth knowing that the pattern is manageable. Thousands of adults have worked through this adjustment phase without stopping treatment.

Food choices that make it better or worse

This is where you have the most immediate control. Because egg burps on Wegovy are driven by fermentation, reducing the amount of high-sulphur food in your stomach at once makes a real difference for many people. Foods that tend to worsen things include eggs (yes, somewhat counterintuitively), cruciferous vegetables like broccoli, cauliflower and cabbage, red meat, garlic, onions and anything heavily processed with preservatives.

Fizzy drinks add a different problem: carbonation introduces extra gas before fermentation even begins, compounding the burping. Plain water, eaten slowly, is a better default. Smaller meals more frequently also help, less food in the stomach at once means less material to ferment during that extended emptying window. Eating quickly or in large portions tends to make things worse.

Some people find that cold or room-temperature food sits better than hot food during the early weeks, though the evidence is anecdotal rather than clinical. Keeping a brief food diary for a week can help you spot your personal triggers, a question our prescribers hear regularly is whether certain foods are worth avoiding, and the answer is almost always individual. For context on how cost fits into your treatment choices, the Wegovy pricing page sets out what a private prescription typically involves.

If loose stools or diarrhoea are accompanying the burping, dehydration can become a concern, small, frequent sips of water matter more than ever at that point.

When to stop managing it yourself and call someone

Most egg burps are an inconvenience, not a warning. But there are symptoms that need prompt medical attention and shouldn't be put down to normal adjustment.

In January 2026, the MHRA issued a Drug Safety Update specifically about GLP-1 medicines (including semaglutide) and flagging acute pancreatitis as an infrequent but serious risk. The key symptom is severe stomach pain, particularly pain that spreads to the back, with or without vomiting. That's different from the bloating, mild cramping or eggy burps that are common early on. If you experience that kind of pain, stop eating and drinking and seek urgent medical attention rather than waiting to see if it passes.

Other reasons to contact a healthcare professional: signs of dehydration from severe vomiting or diarrhoea (dark urine, dizziness, feeling faint), an allergic reaction (rash, swelling, difficulty breathing), or any symptom that feels disproportionate to what you'd expected. You can also report unexpected side effects through the MHRA's Yellow Card scheme, which helps regulators track safety signals across the population.

If you'd like to talk through semaglutide-related eggy burps with a clinician before they become a reason to pause treatment, our team is available seven days a week. When you're ready, starting a free consultation puts you in front of a GPhC-registered prescriber who can review your full picture and advise on managing side effects alongside your treatment plan.