How long do sulphur burps last with Mounjaro — and what can you do about them?

Step 1, why the burps appear in the first place

Mounjaro (tirzepatide) slows the rate at which your stomach empties its contents into the small intestine. That is part of why it reduces appetite and helps with weight management. The knock-on effect is that food, particularly high-protein and high-sulphur foods, sits in the digestive tract for longer. Gut bacteria get more time to ferment that food, and one of the gases they produce is hydrogen sulphide, the compound responsible for the egg-like smell.

This is not an allergic reaction or a sign that tirzepatide is damaging anything. It is a predictable consequence of the medicine doing what it is designed to do. You can read a fuller breakdown of the mechanism on our guide to sulphur burps and Mounjaro. The NHS's patient-level information on tirzepatide lists gastrointestinal effects (including burping) among the common side effects reported during clinical trials, which enrolled thousands of adults over 72 weeks. NHS guidance on tirzepatide is a useful first reference if you want to cross-check what you're experiencing.

Step 2, the typical timeline from first dose through dose increases

For most people, sulphur burps arrive within a day or two of the first injection or a dose step-up. The peak is usually the 24–72 hour window that follows the injection, when tirzepatide's plasma concentration is at its highest and gastric emptying is most slowed.

By around day 7 to 10, the majority of people report a clear improvement, the gut is beginning to adapt, emptying patterns normalise slightly, and the bacterial fermentation slows down. By the two-week mark at a stable dose, most people find the burps have largely resolved or dropped to a manageable level. How long sulphur burps last on Mounjaro can vary, though, someone who eats a large high-fat meal the evening of their injection is giving their digestive system considerably more to ferment than someone eating lightly.

The pattern tends to repeat, in a milder form, each time the dose goes up. So if you sailed through 2.5 mg and then hit burps at 5 mg, that is entirely normal. Each new dose level usually brings a shorter adjustment window than the first, because your gut is already partially adapted to the medicine's mechanism.

It is worth knowing that the cost of Mounjaro treatment (which our Mounjaro prescribing page explains in full) covers each dose stage with clinical review built in, so you are not navigating these adjustments alone.

Step 3, what makes them last longer, and what tends to shorten them

Certain foods extend the problem. Cruciferous vegetables (broccoli, cauliflower, cabbage), eggs, garlic, onions and red meat are all high in sulphur compounds. Eating them in the days around your injection gives gut bacteria more substrate to work with. Large portions and high-fat meals slow gastric emptying further on top of what Mounjaro is already doing, a compounding effect.

Carbonated drinks add gas directly to a digestive system that is already producing more of its own. Some people find coffee on an empty stomach worsens things. None of this means permanent avoidance, but timing matters, and cutting back on the biggest culprits in the 48 hours post-injection can meaningfully reduce how long the burps last.

Practical things that tend to help: smaller, lower-fat meals; spacing food out rather than eating one large evening meal; keeping well hydrated; and eating more slowly. Our overview of what helps with sulphur burps from Mounjaro goes into specific strategies. There is also useful detail in our broader guide on stopping Mounjaro sulphur burps for people finding them particularly stubborn.

One practical note: if your injection day happens to fall over a bank holiday or you've stocked up ahead of a holiday abroad, the timing patterns above still apply, it's the dose, not the calendar, that drives the adjustment window.

Step 4, when sulphur burps signal something worth checking

Sulphur burps alone, even when frequent, are almost always benign. But the picture changes if they come alongside severe or persistent abdominal pain, especially pain that radiates to the back. In January 2026, the MHRA issued a Drug Safety Update reminding patients and clinicians that acute pancreatitis is an infrequent but serious side effect of GLP-1 medicines including tirzepatide. Severe, persistent stomach pain with or without vomiting is a reason to seek urgent medical attention, not to wait and see. The MHRA's Yellow Card scheme allows patients to report suspected side effects directly if they wish to do so.

Beyond pancreatitis, burps that persist for more than three weeks at a stable dose, or that are accompanied by significant nausea or vomiting that is stopping you eating or drinking, are worth a prescriber conversation. Dehydration from repeated GI symptoms can affect kidney function and should not be left unaddressed. Our full side effects overview for Mounjaro covers the wider picture, including which symptoms settle on their own and which need clinical input. You can also compare notes on the nausea timeline in our guide to how long nausea lasts with Mounjaro, since the two symptoms often travel together.

If you have questions your prescriber has not yet answered, or you are considering starting Mounjaro and want to understand what to expect, our clinical team is available to help. Start your free consultation and a GPhC-registered prescriber will review your case the same day.