What are the most common GLP-1 side effects?

What each label lists as a common side effect

These are the "at least 5%" lists from each label, per the FDA prescribing information as of August 2026. They are lists of what was reported, not a ranking of severity.

Ozempic (semaglutide) injection: nausea, vomiting, diarrhea, abdominal pain, and constipation.

Wegovy (semaglutide), in adults or pediatric patients aged 12 years and older: nausea, diarrhea, vomiting, constipation, abdominal pain, dysesthesia, headache, fatigue, dyspepsia, dizziness, abdominal distension, eructation, hypoglycemia in patients with type 2 diabetes, flatulence, gastroenteritis, gastroesophageal reflux disease, and hair loss.

Zepbound (tirzepatide): nausea, diarrhea, vomiting, constipation, abdominal pain, dyspepsia, injection site reactions, fatigue, hypersensitivity reactions, eructation, hair loss, and gastroesophageal reflux disease.

Mounjaro (tirzepatide): nausea, diarrhea, decreased appetite, vomiting, constipation, dyspepsia, and abdominal pain.

Four labels, four lists, one overlap: nausea, diarrhea, vomiting, constipation and abdominal pain are on all of them.

How often each effect was reported

These figures come from placebo-controlled trials as reported on the labels; we do not have a sourced real-world prevalence figure to place beside them.

Semaglutide injection (Ozempic). In placebo-controlled trials of OZEMPIC injection, per the label as of August 2026, nausea occurred in 15.8% of patients on 0.5 mg and 20.3% on 1 mg; vomiting in 5% and 9.2%; and diarrhea in 8.5% and 8.8%.

Tirzepatide (Zepbound). In the Zepbound weight-reduction trials, as reported on the label as of August 2026, nausea was reported by 25% of patients on 5 mg, 29% on 10 mg, and 28% on 15 mg, versus 8% on placebo; diarrhea by 19%, 21%, and 23%, versus 8% on placebo; vomiting by 8%, 11%, and 13%, versus 2% on placebo; and constipation by 17%, 14%, and 11%, versus 5% on placebo.

Constipation was reported at a lower rate at the higher doses in that list, while nausea, diarrhea and vomiting were not.

Tirzepatide (Mounjaro). In placebo-controlled trials, per the Mounjaro label as of August 2026, nausea was reported in 12% (5 mg), 15% (10 mg), and 18% (15 mg) of Mounjaro-treated patients versus 4% with placebo, and diarrhea in 12%, 13%, and 17% versus 9% with placebo.

How often side effects end treatment. In the weight-reduction trials behind each label, permanent discontinuation because of adverse reactions was reported in 6.8% of patients on Wegovy 2.4 mg injection versus 3.2% on placebo — most often for nausea (1.8% versus 0.2%), vomiting (1.2% versus 0%) and diarrhea (0.7% versus 0.1%). Across the pooled Zepbound trials, 4.8% of patients on 5 mg, 6.3% on 10 mg and 6.7% on 15 mg discontinued because of adverse reactions, versus 3.4% on placebo (label figures as of August 2026).

A much higher number circulates, and it does not apply here. In SELECT — a roughly four-year cardiovascular outcomes trial in adults with overweight or obesity and without diabetes, not a weight-management registration trial — adverse events leading to permanent discontinuation occurred in 16.6% of semaglutide recipients versus 8.2% on placebo. A longer trial in an older population with established cardiovascular disease accumulates more discontinuations than a 68- or 72-week weight-management trial does. Treat 16.6% as a fact about that trial, not as the rate for someone starting a GLP-1 for weight management.

The Mounjaro and Zepbound figures are for the same molecule but come from different trial programs and populations, so they are not a comparison of one drug against another — and the semaglutide and tirzepatide figures are not comparable to each other either.

A note on hair loss

Hair loss appears on both the Wegovy and Zepbound "at least 5%" lists, and it is the effect readers most often over-attribute to the drug itself. Both labels tie it to the weight reduction rather than presenting it as a direct drug effect.

The Wegovy label states that hair loss adverse reactions in Wegovy injection-treated patients "were associated with weight reduction," and reports hair loss in 3.3% of patients treated with Wegovy 2.4 mg (4% of females, 0.9% of males) versus 1% of placebo-treated patients (2% of females, no males). In a pediatric trial it was reported in 4% of patients on 2.4 mg and in no placebo-treated patients.

The Zepbound label uses the same phrasing — hair loss adverse reactions "were associated with weight reduction" — and reports it more frequently in female than male patients in both arms: 7.1% of females versus 0.5% of males on Zepbound, against 1.3% of females and no males on placebo. No Zepbound-treated patient discontinued treatment because of hair loss; one placebo-treated patient did (all label figures as of August 2026).

Two things follow. Hair shedding was reported in the placebo groups too, so it is not something only the medication produces. And neither label states a mechanism, so this page does not offer one — if hair shedding is what is worrying you, that is a question for your prescriber rather than something to read off a rate table.

Where these effects sit in the dose schedule

Every label reports its adverse-reaction rates by dose level, so the dose you are on is part of the answer.

Wegovy injection is escalated on a 4-week-per-step schedule: 0.25 mg once weekly for weeks 1-4, 0.5 mg for weeks 5-8, 1 mg for weeks 9-12, 1.7 mg for weeks 13-16, then a maintenance dose from week 17 onward.

Wegovy tablets are escalated on a 30-day-per-step schedule: 1.5 mg once daily on days 1-30, 4 mg on days 31-60, 9 mg on days 61-90, then 25 mg once daily as the maintenance dose from day 91 onward.

Zepbound starts at 2.5 mg injected subcutaneously once weekly for 4 weeks — an initiation dosage, not approved for maintenance — then increases to 5 mg once weekly, and may be increased in 2.5 mg increments after at least 4 weeks on the current dose.

OZEMPIC injection is started at 0.25 mg once weekly. The recommended starting dosage of Mounjaro is 2.5 mg injected subcutaneously once weekly.

The labels do say something about where in that schedule the trouble clusters. Per the Zepbound label as of August 2026, the majority of nausea, vomiting and diarrhea events occurred during dose escalation and decreased over time, and the majority of patients who stopped because of adverse reactions did so during the first few months of treatment. That is a direction, not a timetable — no source cited here gives a typical number of days for a symptom to appear or ease, so this page does not state one.

Side effects by molecule and form

Semaglutide comes in both forms. Wegovy is marketed in two distinct dosage forms under a single brand name and a single FDA label: WEGOVY (semaglutide) injection, solution, and WEGOVY (semaglutide) tablet. Wegovy tablets are taken orally once daily on an empty stomach in the morning with up to 4 ounces of water; the patient must wait at least 30 minutes before eating food, drinking other beverages, or taking other oral medications.

Oral semaglutide has its own trial data. In OASIS 4, per the source reviewed as of August 2026, gastrointestinal adverse events were more common with oral semaglutide 25 mg than with placebo (74.0% versus 42.2%). That is a count of any gastrointestinal adverse event — a wider net than the per-symptom rates above, and not comparable to them.

Tirzepatide is injection-only. The FDA labels describe Zepbound and Mounjaro only as injections for subcutaneous use; no oral dosage form of either is listed. Injection site reactions appear on the Zepbound list above; there is no equivalent for a tablet.

Compounded products. Compounded medications are not reviewed or approved by the FDA for safety or effectiveness, and we do not have a separate sourced adverse-reaction list for compounded semaglutide or compounded tirzepatide.

Peptides. The peptide side-effect profile is not covered by our sources, so do not treat the figures above as applying to peptides.

When to contact a clinician

The reason this section exists is the labels' Warnings and Precautions sections, not the routine gastrointestinal effects.

These are uncommon, but potentially serious. They belong in a different mental category from the nausea rates above, and the reported frequencies are much lower. In the Wegovy weight-reduction trials, cholelithiasis was reported by 1.6% of injection-treated patients versus 0.7% on placebo, and cholecystitis by 0.6% versus 0.2%. In the pooled Zepbound trials, cholelithiasis was reported in 1.1% versus 1% on placebo, cholecystitis in 0.7% versus 0.2%, and severe hypersensitivity reactions in 0.1% versus none on placebo. Severe gastrointestinal adverse reactions were reported in 4.1% of Wegovy injection patients versus 0.9% on placebo, and in 1.7% to 3.1% of Zepbound patients across dose levels versus 1% on placebo (all label figures as of August 2026). Low frequency is not the same as low consequence — the point of listing them is that they need action, not that they are likely.

Wegovy's Warnings and Precautions include risk of thyroid C-cell tumors, acute pancreatitis, acute gallbladder disease, hypoglycemia, acute kidney injury due to volume depletion, severe gastrointestinal adverse reactions, hypersensitivity reactions, diabetic retinopathy complications in patients with type 2 diabetes, heart rate increase, and pulmonary aspiration during general anesthesia or deep sedation.

The Zepbound label's Warnings and Precautions section covers risk of thyroid C-cell tumors, severe gastrointestinal adverse reactions, acute kidney injury due to volume depletion, acute gallbladder disease, acute pancreatitis, hypersensitivity reactions, hypoglycemia, diabetic retinopathy complications in patients with type 2 diabetes mellitus, pulmonary aspiration during general anesthesia or deep sedation, and never sharing a Zepbound KwikPen between patients.

The one connection worth understanding. The routine gastrointestinal effects above and the serious warnings are not separate lists — one leads to the other. Both labels report postmarketing cases of acute kidney injury, in some requiring hemodialysis, and both state that the majority of those cases occurred in patients whose gastrointestinal reactions — nausea, vomiting or diarrhea — led to dehydration. Both instruct clinicians to monitor kidney function in patients reporting reactions that could cause volume depletion, especially during initiation and dose escalation.

That is what turns a nausea rate into something clinically meaningful. If vomiting or diarrhea is stopping you keeping fluids down, that is a reason to contact your prescriber, not something to wait out.

Three more specifics worth carrying with you:

• Acute pancreatitis has occurred in clinical trials with semaglutide; Wegovy should be discontinued promptly if pancreatitis is suspected and should not be restarted if pancreatitis is confirmed.
• The Zepbound label warns of pulmonary aspiration during general anesthesia or deep sedation, a consideration relevant to periprocedural planning. Tell any surgical, dental or anesthesia team that you are on this medication.
• Zepbound is contraindicated in patients with known serious hypersensitivity to tirzepatide or any of its excipients; serious hypersensitivity reactions including anaphylaxis and angioedema have been reported with tirzepatide.

Two more rules: Wegovy is contraindicated in patients with a personal or family history of medullary thyroid carcinoma (MTC) and in patients with Multiple Endocrine Neoplasia syndrome type 2 (MEN 2). And concomitant use of Wegovy tablets or Wegovy injection with other semaglutide-containing products or with any other GLP-1 receptor agonist is not recommended.

One drug interaction is easy to miss. Females of reproductive potential using oral hormonal contraceptives should switch to a non-oral contraceptive method or add a barrier method of contraception for 4 weeks after initiating Mounjaro and for 4 weeks after each dose escalation.

Pregnancy is the reason that interaction matters. Both labels state plainly that weight loss offers no benefit to a pregnant patient and may cause fetal harm. The Zepbound label advises pregnant patients that weight loss is not recommended during pregnancy and to discontinue Zepbound when a pregnancy is recognized; the Wegovy label directs prescribers to discontinue Wegovy in pregnant patients who are using it for weight reduction. Available data in pregnant patients are insufficient to establish a drug-associated risk of major birth defects or miscarriage, and both labels note potential fetal risk based on animal reproduction studies. If you are pregnant, think you might be, or are planning a pregnancy, raise it with your prescriber before your next dose.

If something changes and you are worried, message your prescriber. Who should not take one of these medications at all is covered separately in who should not take a GLP-1.

What being in a supervised program changes

Measured prescribes FDA-approved GLP-1 medications and compounded alternatives, specifically semaglutide (Ozempic, Wegovy), tirzepatide (Mounjaro, Zepbound), compounded alternatives when brand medications are unavailable, and oral medications including metformin, topiramate, and bupropion/naltrexone. Per Measured's medications disclosure, all healthcare providers on its platform are licensed U.S. physicians or nurse practitioners with training and experience in obesity medicine and weight management.

A Measured patient's care team includes their provider, a Registered Dietitian, and a care coordinator, with unlimited messaging access. Measured states video is not required for medication consultations, and that medical evaluations and follow-up care are conducted asynchronously through secure, HIPAA-compliant messaging within the Measured patient portal — so a side effect can be raised in writing on the day it happens.

Our sourced set does not contain a dose-hold or anti-nausea protocol, so we do not describe one here.

On eligibility: whether a particular medication is appropriate for you is a clinical decision made by a licensed provider, based on that medication's FDA-approved indication. More on the prescribing path in how to get a GLP-1 prescription online.

Common questions

Do GLP-1 side effects go away?

Partly answerable. Per the Zepbound label as of August 2026, the majority of nausea, vomiting and diarrhea events occurred during dose escalation and decreased over time, and most patients who discontinued because of adverse reactions did so during the first few months of treatment. What no source cited here provides is a typical number of days for a symptom to appear or resolve, so this page does not state one. Ask your prescriber about your own timeline.

Which GLP-1 has the fewest side effects?

The numbers on each label come from that drug's own placebo-controlled trials, in different populations, at different doses. They are not head-to-head comparisons, and this page does not rank the medications against each other.

Can I take something for the nausea?

Our sourced set does not cover anti-nausea options or any Measured protocol for them, so this page does not list any. Symptom management is a separate topic and is not covered here.

Are side effects worse at higher doses?

It depends on the effect. The broad pattern across the labels quoted here is that gastrointestinal effects become more common as the dose rises: Zepbound diarrhea went from 19% to 21% to 23% across the 5 mg, 10 mg and 15 mg levels, vomiting from 8% to 11% to 13%, and Mounjaro nausea from 12% to 15% to 18%.

Individual effects do not all follow that pattern, though. Zepbound nausea was highest at 10 mg (29%) rather than at 15 mg (28%), and constipation moved the other way entirely, falling from 17% to 14% to 11% as the dose rose. Read the figures in the rates section rather than assuming a single direction.

Does a compounded version have the same side effects?

Compounded medications are not reviewed or approved by the FDA for safety or effectiveness. We do not have a separate sourced adverse-reaction list for compounded semaglutide or compounded tirzepatide, so this page does not state one.

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This page is drawn from FDA prescribing information on DailyMed and from peer-reviewed trial publications, reviewed as of August 2026. It is general information, not medical advice, and it is not a statement about what any particular insurance plan covers. Clinical review byline pending.