Why Does Gas Smell So Bad on Ozempic? GLP-1s, Sulfur Burps, and What Helps

You expected the change in appetite. Maybe even the nausea. What nobody warned you about was the smell.

If your gas or burps have smelled like rotten eggs since you started Ozempic, Wegovy, Mounjaro, or Zepbound, you’re not imagining it, and you’re far from alone. Many GLP-1 users talk about it with each other, but few bring it up at the doctor’s office.

The good news is that there’s a clear reason it happens. It often eases as your body adjusts, and there’s a lot you can do in the meantime.

The Short Answer

GLP-1 medications slow down how quickly food moves through your digestive tract. That extra time gives gut bacteria longer to break down sulfur-containing foods, and one byproduct is hydrogen sulfide, the gas that smells like rotten eggs. When it comes up, you get sulfur burps. When it moves down, you get gas that smells noticeably stronger than before.

Many people on GLP-1s also eat more protein and less fiber than they used to, which adds more fuel to the same process. If your main concern is how much more gas you’re passing, not just how it smells, see our guide Does Ozempic Make You Fart?

How Common Is This?

In the clinical trials behind Wegovy (semaglutide 2.4 mg, the same active ingredient as Ozempic), 7% of people on the medication reported belching, compared with under 1% on placebo. Flatulence was reported by 6% versus 4%, and bloating by 7% versus 5%. Constipation also affects gas odor, and it was reported by 24% versus 11%.¹

Trials don’t measure smell, so “sulfur burps” and “smelly gas” don’t show up as their own line items. Real-world reports suggest they’re more common than the numbers imply, and digestive side effects in general were reported most often while people were stepping up their dose.¹

Why GLP-1s Make Gas Smell Worse

1. Food stays in your stomach longer

Slowing digestion is part of how these medications work. It’s what keeps you feeling full, and Ozempic’s prescribing information notes a delay in stomach emptying in the period right after meals.² Food that stays in the stomach longer has more time to ferment, which is the most likely source of sulfur burps. No trial has measured sulfur burps directly, so this is the best-supported explanation rather than a proven one.

2. Slower transit and constipation

The slowdown doesn’t stop at the stomach. When stool moves more slowly through the colon, bacteria have more time to ferment what’s there, and odor compounds build up. If you’re going less often than you used to, that’s very likely contributing.

3. The high-protein shift

People on GLP-1s are often encouraged to prioritize protein to protect muscle while losing weight. That’s sound advice, but meat, eggs, and dairy are rich in sulfur-containing amino acids called cysteine and methionine. Research shows that high-protein, lower-carbohydrate diets increase hydrogen sulfide in the colon as bacteria ferment the protein that reaches it.³ We cover this in more depth in Protein Farts: Why Your High-Protein Diet Is Wrecking the Air Around You.

4. Protein shakes and “diet” snacks

Many protein powders are whey-based and can contain lactose. Protein bars and low-sugar snacks often use sugar alcohols like sorbitol, maltitol, or xylitol, which are well known for causing gas and bloating. If you added these around the time you started your medication, they may be a bigger part of the picture than the medication itself.

5. Less fiber overall

Eating much less often means eating less fiber, too. Fiber keeps things moving, and certain fibers and resistant starches can reduce protein fermentation in the colon.³ Less of it can tip the balance toward stronger odor.

6. Dose increases

Digestive side effects tend to peak when you start the medication and after each dose increase, then ease as your body adapts.¹ If the smell got worse right after a dose change, you’re seeing a very common pattern.

What Helps: Practical Fixes

Eat smaller, slower meals

A large meal on a slowed-down stomach creates a backlog. Smaller portions, eaten slowly, with a stop at the first sign of fullness, give your gut less to ferment at once. Rich, high-fat meals slow emptying even further, so lighter meals usually go better.

Spread your protein through the day

You don’t need to cut protein. Try spreading it across meals and snacks instead of eating most of it at dinner. Smaller amounts give your small intestine a better chance to absorb it before it reaches the colon.

Ease up on high-sulfur foods for now

Eggs, red meat, garlic, onions, broccoli, cauliflower, Brussels sprouts, cabbage, and dairy are the usual suspects. Try trimming one or two for a week or two and notice whether the odor changes. Think of it as a short experiment, not a permanent diet.

Read your protein labels

If you rely on shakes or bars, look for whey isolate or a lactose-free option, and scan the ingredients for sugar alcohols (anything ending in “-itol”). Swapping products is one of the easiest changes you can make, and it often pays off fast.

Stay ahead of constipation

Drink water steadily through the day and keep up gentle movement. A 10 to 15 minute walk after meals can help keep things moving. Add fiber gradually, since big jumps cause more gas, not less. Our guide Why Do Beans Make You Fart? explains how to increase fiber without the side effects.

Cut back on bubbles and swallowed air

Carbonated drinks, chewing gum, drinking through straws, and eating quickly all add air that has to come back out, often carrying sulfur with it.

Ask your pharmacist about over-the-counter options

Simethicone (Gas-X) can ease gas pressure and bloating. Learn more about how it works in Does Gas-X Make You Fart? The Truth About Simethicone. Bismuth subsalicylate (Pepto-Bismol) can help with sulfur odor, but it isn’t right for everyone. That includes people who take blood thinners, are sensitive to aspirin, or are pregnant. It can also temporarily darken your stool and tongue. Check with your pharmacist before adding anything new.

Talk to your prescriber about dosing

If symptoms flared after a dose increase, ask whether staying at your current dose a little longer before stepping up is an option. The Wegovy prescribing information allows prescribers to delay a dose increase by four weeks when a dose isn’t well tolerated.¹ Don’t adjust your dose on your own.

When to Call Your Doctor

Smelly gas and sulfur burps on their own are usually more embarrassing than harmful. Contact your doctor promptly if they come with any of the following:²

• Severe or persistent abdominal pain, especially pain that spreads to your back
• Ongoing vomiting or trouble keeping fluids down
• Signs of dehydration, like dizziness or very dark urine
• Pain in the upper right abdomen, fever, or yellowing of your skin or eyes
• Blood in your stool, or black stool that isn’t explained by bismuth
• Diarrhea that won’t let up

It’s also worth bringing up symptoms that last for months after your dose has stabilized. Your doctor may want to check for other causes, such as small intestinal bacterial overgrowth (SIBO).

Getting Through the Adjustment Period

For many people, the hardest part isn’t the physical discomfort. It’s the worry. You might feel it in a meeting, in the car, or on the couch next to a partner. Diet changes take a week or two to show results, and dose adjustments take longer. In that window, it helps to have something that works from day one.

That’s where Shreddies comes in. Our underwear is made with Zorflex® activated carbon, a filter panel that traps gas odor, including sulfur compounds, before it can escape. It gives you quiet, everyday backup while you and your provider figure out what helps your body adjust.

To be clear about what Shreddies do: they filter gas odor only. They aren’t designed for bladder leaks or incontinence, and they can’t help with burps. For flatulence, though, they can take a lot of the stress out of the adjustment period.

Find Your Fit

Shreddies for Men

Confidence while your body adjusts

Hipsters and support boxers made with Zorflex® activated carbon that filters gas odor. Everyday backup through dose changes, long meetings, and everything in between.

Shop Men's

Shreddies for Women

Quiet backup, all day long

Hi-waist and bikini brief styles with Zorflex® activated carbon built right in. No inserts, no fuss, so your attention stays on your day, not your digestion.

Shop Women's

Frequently Asked Questions: Gas and GLP-1s

How long does smelly gas last on Ozempic?

For most people, it’s worst in the first several weeks and after each dose increase, then improves as the body adapts. If you stop the medication, keep in mind that semaglutide stays in your system for about five weeks after your last dose, so digestive effects fade gradually rather than overnight.²

Do Mounjaro and Zepbound cause sulfur burps too?

They can. Tirzepatide (Mounjaro, Zepbound) slows digestion in a similar way, so the same causes and fixes apply. Some people find one medication easier on their stomach than another, which is worth discussing with your prescriber if symptoms don’t improve.

Is smelly gas on a GLP-1 a sign something is wrong?

Usually not. On its own, it’s a common and expected side effect of slower digestion. Call your doctor if it comes with severe pain, ongoing vomiting, fever, or changes in your stool like blood.

Should I stop eating protein to fix it?

No. Protein matters while you’re losing weight. Spreading it across the day, choosing lactose-free or isolate protein powders, and skipping products with sugar alcohols usually helps more than cutting back.

Do probiotics help with GLP-1 gas?

The evidence is mixed. Some people notice improvement with yogurt, kefir, or a probiotic supplement, and others don’t. Ask your provider before starting a supplement, especially if you have other digestive conditions.

Can Shreddies help with sulfur burps?

No. Shreddies filter odor from flatulence only, using Zorflex® activated carbon. For burps, the meal, food, and dosing changes above are your best bet.

Sources

1. Novo Nordisk. Wegovy (semaglutide) Prescribing Information. U.S. Food and Drug Administration, revised June 2026.
2. Novo Nordisk. Ozempic (semaglutide) Prescribing Information. U.S. Food and Drug Administration, revised May 2026.
3. Yao CK, Muir JG, Gibson PR. Review article: insights into colonic protein fermentation, its modulation and potential health implications. Alimentary Pharmacology & Therapeutics, 2016;43(2):181–196.