GLP-1 Constipation: How Common It Is on Each Drug, Why It Happens, and Which Laxatives Have Evidence

Short answer: constipation is listed as a common reaction on the FDA label of every semaglutide and tirzepatide medicine. In the label trials it was reported by 3% to 24% of people on the drug, against 1% to 11% on placebo, highest in the obesity trials of Wegovy and Zepbound.^[1][2][3] The 2025 joint nutrition advisory says to manage it early, with fluids and fiber from food added gradually.^[4] Of the laxative types, polyethylene glycol has the strongest guideline backing; which one, if any, is a question for your prescriber or pharmacist.^[5]

This page is the cross-drug overview: the label numbers for each medicine side by side, why these drugs slow things down, what the guidance says to do first, how the laxative types compare in the evidence, and the signs that need urgent care. It sits inside our guide to what to eat when you're eating less. The food side has its own pages: fiber and staying regular on a GLP-1 and, for tirzepatide alone, Zepbound and constipation.

General information, not medical advice. Constipation on a GLP-1 can have other causes, and some laxatives do not suit some people. Ask your prescriber or pharmacist before starting any.

How common is constipation on Ozempic, Wegovy, Mounjaro and Zepbound?

Every one of these labels lists constipation among its most common adverse reactions, in section 6.1.^{[3][6][1][7][2]} The rates below are the share of people in each label's placebo-controlled trials who reported it at least once.

Medicine (ingredient)	Who was studied	Constipation on the drug	On placebo
Ozempic injection (semaglutide)	Adults with type 2 diabetes; 2 trials, about 33 weeks on average	5% on 0.5 mg; 3.1% on 1 mg	1.5%[3]
Rybelsus and Ozempic tablets (oral semaglutide)	Adults with type 2 diabetes; 2 trials, about 42 weeks on average	6% on 7 mg; 5% on 14 mg	2%[6]
Wegovy injection (semaglutide)	Adults with obesity or overweight; 3 trials, up to 68 weeks	24% on 2.4 mg	11%[1]
Wegovy injection, 7.2 mg (semaglutide)	Adults with obesity; 2 trials, 72 weeks	20% on 7.2 mg (19% on 2.4 mg in the same trials)	8%[1]
Wegovy tablets (oral semaglutide)	Adults with obesity or overweight; 1 trial, up to 64 weeks	No separate figure: the label says the types and frequency of common reactions were similar to the injection's	–[1]
Mounjaro (tirzepatide)	Adults with type 2 diabetes; 2 trials, about 37 weeks on average	6% on 5 mg; 6% on 10 mg; 7% on 15 mg	1%[7]
Zepbound (tirzepatide)	Adults with obesity or overweight; 2 trials, 72 weeks	17% on 5 mg; 14% on 10 mg; 11% on 15 mg	5%[2]

From the adverse-reaction tables in section 6.1 of each prescribing information, as current on November 13, 2026. Zepbound's row counts reports of hard stool as well as constipation. The Rybelsus label now also covers semaglutide tablets sold as Ozempic tablets, in different strengths, on the same trial data.^[6]

Three things to keep in mind when reading the table:

• It is not a ranking. Every label warns that rates from one drug's trials cannot be directly compared with rates from another's.^[2] The trials enrolled different people, at different doses, for different lengths of time.
• Look at the placebo column too. The obesity trials had more constipation in both groups. The 2025 joint advisory makes the same point about semaglutide 2.4 mg and tirzepatide 15 mg: differences between the drugs may reflect different background rates in the placebo groups, and the proportional increase over placebo is similar for many reactions.^[4]
• A higher dose does not always mean more. On Zepbound the rate was highest at the lowest dose, and on Ozempic it was higher on 0.5 mg than on 1 mg.^[2][3]

The tirzepatide numbers are covered in more depth in Zepbound and constipation.

Does GLP-1 constipation go away?

For many people it eases, but it tends to last longer than the other stomach symptoms. A 2023 expert consensus on managing these reactions reports that constipation can start in the first 16 weeks, particularly the first 28 days, and that in people with obesity on a GLP-1 medication it lasted a median of 47 days.^[8] The joint advisory says digestive reactions are most likely in the first weeks and after dose increases, and tend to become less frequent and less severe on a stable dose.^[4] The labels themselves do not give a time course for constipation.

The advisory adds one warning: constipation that goes on for a long time can lead to reactive diarrhea, so loose stools after a slow spell are not always a sign that it has resolved.^[4]

Why do GLP-1 medications cause constipation?

The labels do not set out a mechanism for constipation. Four documented effects point the same way:

• Slower movement through the gut. Every one of these labels says the drug delays gastric emptying.^[3][2] Beyond the stomach, an infusion of the body's own GLP-1 hormone reduced motility in the upper small intestine and suppressed the migrating motor complex, the wave that sweeps the gut between meals, in healthy adults and people with irritable bowel syndrome.^[9]
• Less food. The joint advisory reports energy intake falling by 16% to 39% against placebo on these medications.^[4] Less food means less bulk and less fiber reaching the colon.
• Less fluid. The 2023 consensus notes that the feeling of fullness leads people to drink less water, which may predispose them to constipation.^[8] GLP-1 drugs lowered fluid intake in animal studies and in a human trial.^[10][11] Normally about a fifth of the day's water comes from food.^[12]
• Fat and protein. Foods high in protein or fat slow gastric emptying further and can make constipation worse, the advisory says, sometimes calling for a temporary cut-back on them.^[4]

Other medicines can add to it. Aluminum- and calcium-containing antacids, iron supplements, narcotic pain medicines, diuretics and some antidepressants are among those the National Institutes of Health lists as making constipation worse,^[13] and the advisory notes that some anti-nausea medicines, such as ondansetron, can worsen constipation too.^[4] A review of everything you take is a reasonable step with your pharmacist.

What do the guidelines say to do first?

Two documents written for people on these medications agree on the basics.

• Start early, not after a week of nothing. The 2025 joint advisory, from the American College of Lifestyle Medicine, the American Society for Nutrition, the Obesity Medicine Association and The Obesity Society, says constipation "should be managed proactively".^[4]
• Fluids. Both the advisory and the consensus put adequate fluid first; the consensus says to drink generous amounts of water or other sugar-free liquids.^[4][8] Daily figures are in how much water to drink on a GLP-1, and the hydration calculator works out a personal number.
• Fiber from food, raised gradually. The advisory recommends "adequate fluids and fiber from foods" and a gradual increase in foods with soluble and insoluble fiber, such as prunes or other dried fruit.^[4] It also suggests going easy on high-fiber foods in the first few days of treatment.^[4] How many grams, and which foods carry the most in a small portion, are in how much fiber a day on a GLP-1 and our fiber in food table.
• Movement. The consensus advises patients to increase physical activity and mobility.^[8] A gastroenterology review is more cautious: exercise is generally beneficial, but its specific effect on constipation is unclear.^[14] A daily walk costs little either way.
• Tell your prescriber if it persists. The consensus says to inform a clinician as soon as possible if constipation persists despite these steps, and that a clinician may consider lowering the dose if symptoms worsen.^[8]

When food and fluid are not enough, the advisory says "additional strategies are often required" and names daily magnesium, fiber supplements or capsules, polyethylene glycol 3350, and stool softeners to avoid straining.^[4] The consensus also mentions stool softeners.^[8] The next section sets out what the evidence says about each type.

What is the best laxative for GLP-1 constipation?

No laxative is approved specifically for constipation caused by a GLP-1 medication, and the strongest evidence on laxatives comes from a different group of people: adults with chronic idiopathic constipation, meaning long-standing constipation without a known cause. The 2023 guideline from the American Gastroenterological Association and the American College of Gastroenterology graded that evidence for each type.^[5] It is the best available guide to which classes work, but it was not written for people on a GLP-1, and the choice for any one person depends on their kidneys, their other medicines and their symptoms.

Type	Examples (generic names)	How it works	2023 guideline recommendation	Notes from the guideline
Bulk-forming fiber	Psyllium, methylcellulose, wheat bran, inulin	Soluble fiber holds water and softens stool; insoluble fiber adds bulk	Conditional; low certainty	Can be first-line, especially when dietary fiber is low. Only psyllium appears effective among the fibers studied. Encourage adequate fluid; gas is common.[5]
Osmotic: polyethylene glycol (PEG)	Polyethylene glycol 3350	Draws water into the bowel	Strong; moderate certainty	Response held over 6 months. Bloating, loose stool, gas and queasiness can occur.[5]
Osmotic: magnesium	Magnesium oxide	Unabsorbed magnesium draws water into the bowel	Conditional; very low certainty	Avoid with kidney impairment, because of the risk of high blood magnesium.[5]
Osmotic: lactulose	Lactulose	A sugar the body does not absorb; draws water into the bowel	Conditional; very low certainty	For people who did not do well on over-the-counter options. Bloating and gas rise with the dose.[5]
Stimulant	Bisacodyl, sodium picosulfate	Prompts the colon to contract and secrete fluid	Strong; moderate certainty, for short-term or rescue use	Short-term means daily use for 4 weeks or less. Abdominal pain, cramping and diarrhea are the common problems.[5]
Stimulant	Senna	Prompts the colon to contract and secrete fluid	Conditional; low certainty	Higher doses can cause abdominal pain and cramping.[5]
Stool softener	Docusate	Lets water into the stool by lowering its surface tension[14]	No recommendation	The panel noted a lack of data on docusate.[5] In one randomized trial in 170 people, it was less effective than psyllium.[14]
Prescription options	Linaclotide, plecanatide, prucalopride, lubiprostone	Increase fluid secretion or bowel contractions	Strong (first three) or conditional (lubiprostone), for people who do not respond to over-the-counter options	A prescriber's decision, not a self-care step.[5]

"Strong" means most people in that situation would want the treatment; "conditional" means many would but many would not, so the decision is more individual.^[5] Many of the trials behind these grades lasted only 4 weeks, so long-term use rests on less evidence.^[5]

Why ask before starting any of them

• Timing around oral medicines. GLP-1 medications delay gastric emptying and may affect how other medicines taken by mouth are absorbed, the labels say.^[3][2] Semaglutide tablets have their own rule: take them on an empty stomach with up to 4 ounces of water and wait at least 30 minutes before food, drink or other oral medicines.^[1][6] A psyllium Drug Facts label says to take it at least 2 hours apart from prescription medicines.^[15]
• Kidneys. Magnesium products are not for everyone with kidney disease.^[5][16] The GLP-1 labels separately warn that fluid lost through vomiting or diarrhea can lead to kidney injury,^[2] which is one reason not to overshoot into diarrhea with a laxative.
• Fluid with fiber. Bulk-forming fiber needs plenty of fluid,^[5] which is harder when appetite and thirst are both low. The fiber types are compared in fiber supplements on a GLP-1, compared.

So the honest answer to "which laxative is best" is: polyethylene glycol and short-term bisacodyl have the best evidence in chronic constipation in general, psyllium is the fiber with evidence, and your prescriber or pharmacist is the right person to say which fits you, especially before you start any.^[5]

When is constipation on a GLP-1 an emergency?

All five labels list, among reports received after the drugs came to market, ileus (the bowel stops moving), intestinal obstruction and severe constipation including fecal impaction.^{[3][6][1][7][2]} These appear in the postmarketing section (6.2), not as a separate warning. Because the reports are voluntary, the labels do not estimate how often they happen. Each label's Warnings section does cover severe gastrointestinal reactions in general: in Wegovy's obesity trials, for example, they were reported by 4.1% on the injection against 0.9% on placebo.^[1]

Get medical help right away for constipation with any of these, which the National Institutes of Health lists:^[13]

• constant pain in the abdomen
• being unable to pass gas
• vomiting
• blood in the stool or bleeding from the rectum
• fever
• lower back pain

The Medication Guides add two more. Tell your healthcare provider about stomach problems that are severe or will not go away. And stop the medicine and call your healthcare provider right away for severe pain in the stomach area that will not go away, with or without vomiting, sometimes felt through to the back, which can be a sign of pancreatitis.^[2] Not being able to keep fluids down is also a reason to call, because dehydration carries its own risks on these drugs; the signs are in GLP-1s and dehydration.

Every question in this cluster, from protein to vitamins, is mapped in our GLP-1 nutrition guide.