Constipation on Ozempic, Wegovy or Mounjaro: Why It Happens and What Helps

Short answer: GLP-1 medicines like semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro, Zepbound) slow down how fast food moves through you. That's part of how they keep you full. It also means stool sits longer, loses more water, and gets harder to pass. In the Wegovy trials, 24% of adults reported constipation, versus 11% on placebo.^[1] What helps is simple: fiber built up slowly, more water than feels normal, smaller meals, and moving every day. If nothing is moving after a few days, call your prescriber.

You started the shot, the food noise got quiet, and now your gut went quiet too. You're not doing anything wrong. Here's why it happens and what to do about it.

Why does a GLP-1 cause constipation?

GLP-1 (you'll also see it written "GLP One") is a hormone your gut already makes after you eat. The medicines copy it at higher, longer-lasting levels. One of its jobs is to slow the stomach down. The Wegovy prescribing information says it plainly: semaglutide delays gastric emptying.^[1]

Three things stack up from there:

• Slower movement. Food leaves the stomach later, and things move more slowly downstream.
• More water pulled out. The longer stool stays in the colon, the more water your body takes back. Harder stool, harder trip.
• Less going in. You're eating less, so there's less food, less fiber and often less fluid moving through.

Timing matters too. On Wegovy, GI reactions increased during dose escalation.^[1] In the main tirzepatide obesity trial, most GI side effects were mild to moderate and happened mainly during dose escalation.^[2]

What helps constipation on a GLP-1?

A 2022 multidisciplinary expert consensus on GLP-1 side effects gives three basics for constipation: get enough fiber, drink generous amounts of water, and increase physical activity.^[3] Here's how to do each without making things worse.

1. Build fiber up slowly

Most adults need 22 to 34 grams of fiber a day.^[4] On a GLP-1 you're eating less, so most people land well under that. Add fiber a little at a time, roughly 3 to 5 grams a week. Dumping a lot of fiber onto a gut that's already moving slowly is a fast way to get gassy and bloated. Good places to start: oats, chia, ground flax, lentils, kiwi, pears and berries.

2. Try psyllium husk

Psyllium is a soluble fiber that holds water all the way through the colon. That's why it softens hard stool and firms loose stool.^[5] The 2023 AGA and ACG guideline on chronic constipation made a conditional recommendation for fiber supplements.^[6] Start with about 1 teaspoon in a full 8-ounce glass of water once a day and build up. Take it at least 2 hours away from other pills, because fiber can change how they're absorbed. More in our psyllium husk guide.

3. Try ground flaxseed

Flaxseed is a fiber you can eat as food. In a randomized, placebo-controlled trial of 53 adults with constipation and type 2 diabetes, 10 grams of flaxseed baked into cookies twice a day for 12 weeks improved constipation symptom scores more than placebo.^[7] It hasn't been studied in people on GLP-1 medicines. Try 1 tablespoon of ground flaxseed at a meal, stirred into oatmeal or yogurt, with a full glass of water. If you're already bloated, start with a teaspoon and increase slowly. Because a GLP-1 slows your stomach, keep the water coming, and talk to your clinician first if you have gastroparesis or a past bowel obstruction.

4. Drink more than feels normal

Fiber without water can backfire. A lot of people on a GLP-1 feel less thirsty and drink less without noticing. Set a floor: a full glass with every meal and one between meals.

5. Move every day

Walking counts. The expert consensus lists more physical activity as a first step for GLP-1 constipation.^[3] A 10 to 15 minute walk after meals is an easy place to start.

6. Give your gut its window

Your gut is most active after you eat, and for a lot of people that's after breakfast. Give yourself unhurried time then instead of fighting it.

7. Ask before you grab a laxative

There are over-the-counter options, and your prescriber or pharmacist can tell you which one fits you and your medication. Ask first.

Can a probiotic help with GLP-1 constipation?

Maybe, and it depends on the strain. A meta-analysis of 14 randomized trials found probiotics shortened whole-gut transit time by about 12 hours on average and added about 1.3 bowel movements a week. The clearest results were for Bifidobacterium lactis.^[8] Those trials weren't in people on GLP-1 medicines, and nobody has run that trial yet. So think of a probiotic as support for regularity next to fiber and water, not a substitute for them.*

And to be clear: no probiotic replaces, copies or boosts a GLP-1 medicine. That's a different category. More on that in GLP-1, probiotics and weight.

Before you add any supplement: if you take an oral semaglutide pill (Rybelsus or the Wegovy pill), don't take it within 30 minutes after your pill. If you have gastroparesis, a past bowel obstruction or bezoar, or trouble swallowing, talk to your clinician first.

When to call your prescriber

• No bowel movement for several days, or it keeps getting worse
• Severe stomach pain that won't go away, with or without vomiting
• A hard, swollen belly, or you can't pass gas
• Vomiting that keeps you from holding down fluids

The prescribing information lists pancreatitis, gallbladder problems and ileus (a stalled bowel) among the serious risks to watch for.^[1] Your prescriber can look at your dose schedule. Don't change it on your own.

Frequently asked questions

Is constipation on Ozempic or Wegovy normal?

It's common. In the Wegovy trials, 24% of adults on semaglutide 2.4 mg reported constipation, compared with 11% on placebo. GI side effects showed up most during dose increases. If yours is severe or not letting up, tell your prescriber.

How long does GLP-1 constipation last?

It varies. In the main semaglutide and tirzepatide trials, GI side effects clustered around dose increases. If you're still stuck once a dose has settled, or it's getting worse, talk to your prescriber rather than waiting it out.

Is it OK to take psyllium husk with a GLP-1?

Psyllium is a common fiber supplement, and expert guidance for GLP-1 constipation starts with getting enough fiber and water. Start with about a teaspoon in a full glass of water, build up slowly, keep it two hours away from other pills, and check with your prescriber or pharmacist first. If you take oral semaglutide (Rybelsus), follow its empty-stomach instructions exactly.

What should I eat for constipation on Mounjaro or Zepbound?

Smaller meals built around fiber you tolerate: oats, chia, ground flax, kiwi, pears, berries, beans and lentils. Drink more water than feels normal. Add fiber gradually so you don't swap constipation for bloating.

Does every GLP One medication cause constipation?

No. In the Wegovy trials, 24% of adults on semaglutide 2.4 mg reported constipation, so most people didn't. GI side effects are common across the whole GLP-1 class, including tirzepatide, and they show up most during dose increases.

Can a probiotic help constipation on a GLP-1?

Some strains support regularity, with the strongest research on Bifidobacterium lactis. None have been tested specifically in people on GLP-1 medicines. Use a probiotic alongside fiber, water and movement, never in place of them, and never in place of your medication.

Keep reading

• Metabolic gut health hub: Akkermansia, GLP-1 and your gut
• GLP-1, probiotics and weight: what the science really says
• GLP-1 and your gut: the bigger picture
• Bloating and gas on a GLP-1
• Nausea and diarrhea on a GLP-1
• Retatrutide and your gut: what the trials show
• Psyllium husk: benefits, dose, and is it a prebiotic?

This article is educational and is not medical advice. It does not replace your prescriber. Never stop, skip or change a GLP-1 dose on your own.

*These statements have not been evaluated by the Food and Drug Administration. Flore products are not intended to diagnose, treat, cure, or prevent any disease.

Ozempic, Wegovy and Rybelsus are registered trademarks of Novo Nordisk A/S. Mounjaro and Zepbound are registered trademarks of Eli Lilly and Company. Flore is not affiliated with or endorsed by either company.

Sources

1. WEGOVY (semaglutide) injection, Prescribing Information. U.S. Food and Drug Administration, 2024.
2. Jastreboff AM, et al. Tirzepatide once weekly for the treatment of obesity. N Engl J Med. 2022;387(3):205-216. PubMed 35658024
3. Gorgojo-Martínez JJ, et al. Clinical recommendations to manage gastrointestinal adverse events in patients treated with GLP-1 receptor agonists: a multidisciplinary expert consensus. J Clin Med. 2022;12(1):145. PubMed 36614945
4. Dietary Guidelines for Americans, 2020-2025. U.S. Department of Agriculture and U.S. Department of Health and Human Services.
5. McRorie JW Jr, McKeown NM. Understanding the physics of functional fibers in the gastrointestinal tract: an evidence-based approach to resolving enduring misconceptions about insoluble and soluble fiber. J Acad Nutr Diet. 2017;117(2):251-264. PubMed 27863994
6. Chang L, et al. American Gastroenterological Association-American College of Gastroenterology clinical practice guideline: pharmacological management of chronic idiopathic constipation. Am J Gastroenterol. 2023;118(6):936-954. PubMed 37204227
7. Soltanian N, Janghorbani M. A randomized trial of the effects of flaxseed to manage constipation, weight, glycemia, and lipids in constipated patients with type 2 diabetes. Nutr Metab (Lond). 2018;15:36. PubMed 29760761
8. Dimidi E, et al. The effect of probiotics on functional constipation in adults: a systematic review and meta-analysis of randomized controlled trials. Am J Clin Nutr. 2014;100(4):1075-1084. PubMed 25099542