GLP-1 Constipation and Diarrhea: What the Labels Report

Short answer: Constipation and diarrhea are two of the most common side effects listed on GLP-1 labels. In weight-reduction trials, constipation was reported by 24% of Wegovy® (semaglutide) patients and diarrhea by 30%, versus 11% and 16% on placebo. The labels also warn that diarrhea, nausea and vomiting can lead to dehydration and kidney problems. This page reports what the labels say. It does not give treatment advice, and your prescriber is the person to ask what to do about your symptoms.

How often did constipation and diarrhea happen in trials?

These are the labels’ own figures from placebo-controlled weight-reduction trials, as listed on DailyMed on October 30, 2026. The trials differ in design, so do not compare the medicines line by line.

Label	Reaction	Placebo	Treated patients
Wegovy injection (2.4 mg)	Constipation	11%	24%
Wegovy injection (2.4 mg)	Diarrhea	16%	30%
Zepbound (three strengths studied)	Constipation	5%	17%, 14%, 11%
Zepbound (three strengths studied)	Diarrhea	8%	19%, 21%, 23%
Foundayo (three strengths studied)	Constipation	9%	20%, 27%, 24%
Foundayo (three strengths studied)	Diarrhea	11%	21%, 23%, 25%

The Zepbound figures are listed in order of strength studied, lowest to highest. Your prescriber chooses what fits you.

What do the labels warn about beyond comfort?

Three label sections matter here:

• Severe stomach and bowel reactions. The Wegovy label says use of the medicine “has been associated with gastrointestinal adverse reactions, sometimes severe,” reported in 4.1% of Wegovy injection patients versus 0.9% on placebo. The Zepbound label reports 1.7%, 2.5% and 3.1% across its three studied strengths versus 1% on placebo. Both say the medicine is “not recommended in patients with severe gastroparesis.”
• Reports after approval. The Ozempic, Mounjaro and Zepbound labels list, among reactions reported after approval, ileus, intestinal obstruction and “severe constipation including fecal impaction.” Those reports are voluntary and come from a population of uncertain size, so the labels say frequency and cause cannot always be reliably established.
• Dehydration and kidney injury. The labels say most reported cases of acute kidney injury happened in patients with “gastrointestinal adverse reactions leading to dehydration such as nausea, vomiting, or diarrhea.”

The Wegovy and Zepbound Medication Guides, the patient-facing leaflets, say diarrhea, nausea and vomiting “may cause a loss of fluids (dehydration)” and tell people to contact their healthcare provider right away about nausea, vomiting or diarrhea “that does not go away.”

What does MedlinePlus say about constipation and diarrhea in general?

MedlinePlus, the NIH patient-information site, defines constipation as “having fewer than three bowel movements a week” and says to check with your provider if your bowel habits change. It suggests asking your provider whether medicines you take may cause constipation, and says to use laxatives “only if your health care provider says you should.” For diarrhea, it says to contact a provider for diarrhea that lasts more than 2 days in an adult, signs of dehydration, or a fever of 102 degrees or higher.

How can you keep track of your symptoms?

Jotting down the day of each shot and when bowel changes start and stop gives your provider a clear picture at the next visit. Weeko, a shot tracker coming to iPhone and Android, is being built around that kind of simple log. It is a logbook, not medical guidance.

For the full side effect picture, see GLP-1 side effects: a plain-language guide. Nausea and vomiting have their own page: GLP-1 nausea and vomiting.

When to call your doctor

Call your prescriber right away, or get emergency care, if you have:

• Stomach problems that are severe or will not go away
• Nausea, vomiting or diarrhea that does not go away
• Signs of dehydration, or decreased urination
• Ongoing, severe pain in the stomach, with or without vomiting

Ask your prescriber or pharmacist before taking any over-the-counter product for symptoms while you are on a GLP-1 medicine.