Why Does Semaglutide Cause Eggy Burps — and Will They Stop?

Why does semaglutide cause that sulphurous smell in the first place?

Semaglutide works partly by slowing down gastric emptying, the rate at which the stomach pushes its contents into the small intestine. That deliberate delay is what helps you feel fuller for longer. It is also, unfortunately, what produces eggy burps. When food sits in the stomach longer than it normally would, bacteria begin fermenting it earlier and more extensively. Hydrogen sulphide, the compound behind that rotten-egg odour, is a byproduct of that fermentation, particularly when sulphur-containing foods (eggs, red meat, cruciferous vegetables, onions, garlic) are involved.

The NHS medicines page for semaglutide lists belching among the common GI side effects of treatment, alongside nausea and changes in bowel habits. Eggy burps are a specific variant of that belching pattern on Wegovy, and they follow the same logic: more gas produced more slowly, with longer contact time in the gut. Understanding the mechanism makes the symptom less alarming. It does not, on its own, mean digestion has broken down, it means the medicine is doing what it is supposed to do.

People who find the broader picture of semaglutide side effects useful can read more on the Wegovy side effects page, which covers the full GI profile in context.

How long do semaglutide eggy burps typically last?

Most people notice them most in the first two to four weeks at any given dose, and then things quieten down. The stomach adapts to the slower emptying rate over time, and the fermentation effect becomes less pronounced. Dose increases tend to bring a temporary recurrence, the digestive system is adjusting again, so a symptom that had faded can return for a week or two before settling once more.

That pattern is worth knowing in advance. It can be disheartening to think you have got past the difficult stage only for the burps to reappear after moving up a dose. They almost always ease again on the same timescale. If they do not (or if they are accompanied by persistent nausea, vomiting that will not settle, or pain) that is worth raising with the prescriber who oversees your treatment, not something to manage alone.

There is also a useful practical detail here: the timing of meals matters more than many people realise. Eating close to bedtime means food sits in a slower stomach through the night, and morning often brings the worst of the eggy burping. Giving yourself two to three hours between the evening meal and lying down is a small change that some patients say makes a noticeable difference.

What can you actually do to reduce eggy burps on semaglutide?

There is no single remedy, but a combination of dietary adjustments helps most people. Temporarily cutting back on sulphur-dense foods (eggs, broccoli, cauliflower, cabbage, onions, garlic, and processed red meat) reduces the substrate available for hydrogen-sulphide production. You do not need to cut them out permanently, and most people reintroduce them gradually as their digestion adapts. Eating smaller portions more slowly is also useful, and our semaglutide burps page walks through why portion size and eating pace matter so much for this particular side effect.

Fizzy drinks and chewing gum introduce additional gas into the upper gut, which can make belching worse even if the underlying sulphur smell is mild. Still water, eaten-not-drunk meals, and pausing halfway through a meal to let fullness signals register all fit the same principle. Some people find that a brief walk after eating helps gastric motility without the pressure of a full workout.

If eggy burps are one of a cluster of GI symptoms (particularly if there is also a strange taste or coating in the mouth) the bad taste in mouth on semaglutide page covers that overlapping experience, which has similar dietary roots.

For information on what these treatments cost privately and what that price includes, the Wegovy pricing page sets out the transparent picture honestly.

When should you speak to a clinician about your symptoms?

Eggy burps are almost always benign. But the GI system is where the more serious (and rare) effects of semaglutide also show up, so it is worth knowing the distinction. The MHRA's January 2026 Drug Safety Update for GLP-1 medicines flagged acute pancreatitis as an infrequent but potentially serious risk: the warning sign is severe, persistent stomach pain that spreads towards the back, which may or may not come with vomiting. That is a different symptom entirely from eggy belching, but anyone who develops that kind of pain should seek medical help promptly rather than waiting to see if it passes.

Similarly, gallbladder problems (which can cause sharp right-sided or upper abdominal pain) are listed as a less common side effect. Eggy burps do not suggest either condition. But if the character of the discomfort shifts from mild GI upset to something more persistent or localised, a prescriber should hear about it. Suspected side effects from any medicine can be reported using the MHRA's Yellow Card scheme, which helps the regulator build a clearer picture of how medicines affect people in real-world use.

At nume, every treatment is overseen by a GPhC-registered Independent Prescriber, and our aftercare team is available seven days a week if a symptom is worrying you between formal reviews. If you are still exploring treatment options and want to understand the broader Wegovy treatment overview, that page sets out the full picture from eligibility to what the prescription process involves.