This is the side effect people email about rather than mention out loud. It arrives about three weeks in, usually after a dose increase, and it is memorable enough that a fair number of people quietly consider stopping the drug over it.
It is also, mechanically, one of the more straightforward problems on this list to fix.
What is actually happening
Every drug in this class slows the rate at which the stomach empties into the small intestine. That is not a side effect; it is a substantial part of how the medication produces fullness in the first place.
The unintended consequence is dwell time. Protein that would ordinarily have moved on within a couple of hours sits there. Sulfur-containing amino acids — cysteine and methionine, abundant in eggs, red meat and whey — become substrate for bacterial fermentation, and one product of that fermentation is hydrogen sulfide.
Hydrogen sulfide is detectable by the human nose at a few parts per billion. You are not producing much of it. You do not need to.
The foods that reliably make it worse
Two separate categories, and people usually only think of the first.
High-sulfur foods — eggs, red meat, whey protein powder, garlic, onions, and the brassicas: broccoli, cauliflower, cabbage, Brussels sprouts. These supply the raw material.
High-fat meals — fried food, cream sauces, pizza, anything heavy. Fat slows gastric emptying further, extending the fermentation window for everything else on the plate.
The second category catches people out because the food itself contains no sulfur to speak of. A steak on its own is manageable. A steak with chips at nine in the evening is a different proposition entirely.
Whey protein deserves a specific mention, because it sits at the intersection of both problems and because so many people on these drugs are told to prioritise protein. If your shake is the trigger, a whey isolate is usually better tolerated than a concentrate, and a plant-based blend — Orgain and Ritual both make ones that work here — often resolves it outright. That is a formulation swap, not a reason to abandon your protein target.
What actually helps
Bismuth subsalicylate. Pepto-Bismol and its generics contain bismuth, which binds hydrogen sulfide to form bismuth sulfide. This is genuine chemistry rather than a folk remedy, and it is why bismuth reduces the smell where simethicone — which only coalesces gas bubbles — does nothing at all. Expect temporary darkening of the tongue and stool, which is harmless. Avoid it if you take anticoagulants, are allergic to aspirin, or are pregnant, and do not run it continuously for weeks without asking someone.
Smaller, earlier, drier meals. Three or four modest meals beat one large one. Finishing eating three hours before lying down matters more on this drug class than it ever did before.
A temporary sulfur reduction. Not a permanent elimination diet. Pull eggs, brassicas and red meat back for a week or two through a dose escalation, then reintroduce them one at a time. Most people find the problem was one specific food rather than the whole category.
Time. This is the part worth saying plainly: for most people it settles. Gastric adaptation happens over weeks, and the burps that dominate week three of a new dose are usually gone by week eight.
Week 3
When sulfur burps typically appear after starting or stepping up a dose
ppb
Concentration at which the human nose detects hydrogen sulfide — parts per billion
Suarez et al., Gut 1998
Week 8
By which most people find the fermentation has settled at a stable dose
What does not help
Simethicone, for the odour. It is a reasonable anti-bloating agent and does nothing whatsoever to hydrogen sulfide.
Probiotics, on current evidence, for this specific symptom. They may be worth taking for other reasons; the data that they resolve sulfur burps does not exist.
Skipping protein. Tempting, and a genuinely bad trade — you are on a drug that costs you lean mass, and cutting protein to avoid a burp is solving the smaller problem while making the larger one worse.
The instinct is to eat less protein. The correct move is to eat the same protein in smaller instalments, further from bedtime.
The version that is not just a burp
Delayed gastric emptying exists on a spectrum, and at the far end of it is gastroparesis — emptying slow enough to cause real trouble.
Get assessed if you have: persistent vomiting, especially of food eaten many hours or a day earlier; inability to keep fluids down for 24 hours; severe or escalating abdominal pain; a visibly distended, tight abdomen; or unintentional symptoms that keep worsening rather than settling after a dose has been held.
The reassuring part
Of all the things this drug class does, this is among the most tractable. It responds to portion size, meal timing, one over-the-counter product with a real mechanism, and patience through a dose step.
Very few people should lose access to an effective medication over a smell.