GLP-1 Constipation: How Common, What Helps, When to Call

Yes, constipation is a known side effect of GLP-1 medications. In the weight-loss trials behind the current labels, 11–17% of people on Zepbound and 24% on Wegovy 2.4 mg reported it, against 5% and 11% on placebo. It tends to start in the first weeks of treatment and, in the semaglutide trials, lasted longer than nausea or diarrhea: a median of 47 days per episode.

Most cases respond to fiber, fluid and movement. A few warning signs mean a call to your doctor the same day, and those are listed below.

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Does Zepbound cause constipation? The label numbers

From the current US prescribing information for each drug, constipation reported in placebo-controlled trials:

The Zepbound figure counts both "constipation" and "feces hard." Rates are higher in the weight-reduction trials than in the diabetes trials, which use different doses and different patients, so compare within a row, not across rows. Every one of these labels also lists ileus, intestinal obstruction and "severe constipation including fecal impaction" among postmarketing reports. Those are rare, and they are the reason the warning signs below matter. Full lists are on the Zepbound, Wegovy, Mounjaro and Ozempic side-effect pages.

Why do GLP-1s cause constipation?

The honest answer is that the exact mechanism is not proven.

• A slower gut. The labels state that tirzepatide and semaglutide delay gastric emptying, which is how food leaves the stomach. Constipation happens further down. An analysis of the STEP semaglutide trials says changes in lower-gut transit "may be responsible for constipation and/or diarrhoea, although evidence is lacking."
• Less fluid. A 2022 expert consensus on GLP-1 side effects notes that people often drink less water because they feel full after the medication, which may predispose them to constipation.
• Less food, and less fiber. The NIDDK lists not eating enough fiber, not drinking enough liquids and changing how much you eat as causes of constipation. A GLP-1 often changes all three at once.

When does it start, and how long does GLP-1 constipation last?

• Onset: the expert consensus puts it within the first 16 weeks, particularly the first 28 days.
• Duration: in the pooled STEP 1–3 trials, the median constipation episode on semaglutide 2.4 mg lasted 47 days (35 days on placebo), compared with 3 days for diarrhea and 8 days for nausea. The share of people with constipation leveled off around week 10.
• Dose increases: in the same trials, most first GI side effects appeared during dose escalation.

No label or trial we found shows a shot-day pattern for constipation. If you think yours follows the dose week, a few weeks of logs will show it.

How to keep things moving: what helps

1. Know your fiber target. The Dietary Guidelines for Americans set fiber at 14 grams per 1,000 calories, which works out to 22–34 grams a day for adults depending on age and sex. On a GLP-1 you may eat far fewer calories than that table assumes; at about 1,400 calories, the same ratio is about 20 grams. A registered dietitian can set the number for you.
2. Add fiber a little at a time. The NIDDK advises raising fiber gradually so your body gets used to it. A sudden jump can add bloating, which many people on a GLP-1 already have.
3. Put a fiber food on the plate with your protein. Good sources the NIDDK lists: oatmeal and other whole grains, beans and lentils, berries, apples with the skin, pears, broccoli, carrots, peas and nuts. Ideas that suit a smaller appetite are in the GLP-1 foods guide, including oatmeal, chia seeds, berries and broccoli.
4. Drink with intent, not only on thirst. Fiber needs fluid to soften stool. The National Academies set adequate total water at about 2.7 liters a day for women and 3.7 liters for men, from all drinks and foods, with about 80% coming from drinks. If you eat less food, you also get less water from food. If you have been told to limit fluids for a heart or kidney condition, follow that instead.
5. Limit low-fiber fillers. The NIDDK names chips, fast food, meat-only meals and processed foods as low or no fiber. You don't have to drop them, but on a smaller appetite they leave less room for fiber. More on this in foods to avoid on a GLP-1.
6. Move every day. Regular physical activity may help relieve constipation, per the NIDDK. A walk after a meal counts.
7. Give your body a routine. The NIDDK suggests trying for a bowel movement 15 to 45 minutes after breakfast, not ignoring the urge, and putting your feet on a footstool.
8. Ask your prescriber or pharmacist which laxative or stool softener is right for you. Options range from fiber supplements to osmotic laxatives, stool softeners and stimulants, and the NIDDK says stimulants are for severe cases or when other treatments have not worked. Your clinician should choose. Tell your pharmacist you take a GLP-1: the labels note these drugs slow stomach emptying and may change how other oral medicines are absorbed.

Never skip, delay or change your GLP-1 dose to manage constipation on your own. If it keeps getting worse, your prescriber can review the dose.

When to call your doctor

Call your doctor right away, or seek urgent care, if constipation comes with any of these:

• No bowel movement plus severe or constant belly pain, bloating, vomiting, or being unable to pass gas. These can be signs of a bowel obstruction or ileus, which the labels list among postmarketing reports.
• Blood in your stool or bleeding from the rectum
• Fever or lower back pain alongside constipation
• Persistent or severe abdominal pain, sometimes spreading to the back, with or without vomiting. That is the labeled warning sign of pancreatitis.
• Stomach problems that are severe or will not go away, which the patient information for these drugs asks you to report

Also see a doctor if constipation does not improve with self-care. If your gut is swinging the other way, see Zepbound diarrhea, and for queasiness, the nausea guide.

What to track, and why

"I'm a bit backed up" is hard for a prescriber to act on. "Constipation at severity 6 for 9 days after my move to 7.5 mg, with water under 1.5 liters most days" gives them something to work with.

In GLP AI, constipation is in the side-effect catalog, and each entry gets a severity from 1 to 10. Log water through the day, and log meals so the app can track fiber alongside the GLP-1 Meal Score. The estimated medication level chart puts symptoms next to your dose week. Before an appointment, export the doctor report PDF (medication history, nutrition, weight and side effects over time) and bring it. The GLP-1 symptom tracker and doctor visit prep pages explain how. Other symptoms are in the side-effects hub.

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Sources verified 2026-10-26

1. Zepbound prescribing information (revised 08/2026): Table 1 constipation (placebo 5%; 5 mg 17%; 10 mg 14%; 15 mg 11%; footnote b "includes constipation, feces hard"); 5.2 severe GI adverse reactions; 5.5 pancreatitis; 6.2 postmarketing ileus, intestinal obstruction, severe constipation including fecal impaction; 7.2 and 12.2 delayed gastric emptying.
2. Mounjaro prescribing information (revised 08/2026): Table 1 constipation (placebo 1%; 6%, 6%, 7%); 6.2 postmarketing.
3. Wegovy prescribing information (revised 06/2026): Table 3 (placebo 11%; 2.4 mg 24%); Table 4 (placebo 8%; 2.4 mg 19%; 7.2 mg 20%); 5.2, 5.6; 6.2 postmarketing; 12.2.
4. Ozempic prescribing information (revised 05/2026): Table 1 (placebo 1.5%; 0.5 mg 5%; 1 mg 3.1%); 6.2 postmarketing; patient information.
5. Saxenda prescribing information (revised 02/2026): Table 2 (placebo 8.5%; Saxenda 19.4%).
6. Rybelsus prescribing information (revised 01/2026): Table 2 (placebo 2%; 7 mg 6%; 14 mg 5%).
7. Wharton S et al. Gastrointestinal tolerability of once-weekly semaglutide 2.4 mg in adults with overweight or obesity. Diabetes Obes Metab. 2022;24(1):94–105: median constipation duration 47 vs 35 days; plateau around week 10; lower-GI transit hypothesis.
8. 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. 2023;12(1):145: onset in first 16 weeks, particularly the first 28 days; reduced water intake.
9. NIDDK: Eating, Diet, & Nutrition for Constipation, Treatment for Constipation and Symptoms & Causes of Constipation.
10. Dietary Guidelines for Americans, 2020–2025, Appendix 1, Table A1-2: fiber goal 14 g per 1,000 kcal (adult goals 22–34 g/day).
11. National Academies: Report Sets Dietary Intake Levels for Water, Salt, and Potassium (2004): total water adequate intake about 2.7 L (women) and 3.7 L (men); about 80% from beverages.