Ozempic, Wegovy and Zepbound side effects: how common are they, and which are serious?

Q: What are the most common side effects of Ozempic, Wegovy and Zepbound?

In the trials behind the US labels, the most common side effects were nausea, diarrhea, vomiting and constipation. Nausea was reported by 44% of adults with obesity or overweight on Wegovy 2.4 mg vs 16% on placebo, and by 25% to 29% on Zepbound vs 8% on placebo.

Q: How long do Ozempic and Wegovy side effects last?

In the pooled STEP 1 to 3 trials of semaglutide 2.4 mg in adults with overweight or obesity, a nausea episode lasted a median of 8 days, diarrhea 3 days and vomiting 2 days. Constipation lasted longer, a median of 47 days. Stomach side effects peaked around week 20, during the dose increases, and then declined.

Q: What are the long-term effects of Ozempic?

In the SELECT trial, 17,604 adults with heart disease and overweight or obesity took semaglutide 2.4 mg or placebo, with a mean follow-up of 39.8 months. 16.6% on semaglutide stopped treatment because of side effects vs 8.2% on placebo. Three years of tirzepatide in the SURMOUNT-1 trial showed no new safety signals.

Q: Are Ozempic side effects different in women?

Hair loss was reported mostly by women: 7.1% of women vs 0.5% of men on Zepbound in its label trials, and 4% vs 0.9% on Wegovy. In the SELECT trial, hip and pelvis fractures were more common on Wegovy than placebo among women, 1% vs 0.2%.

Q: What are the dangers of Ozempic?

The US labels for Ozempic, Wegovy, Zepbound and Mounjaro carry a boxed warning about thyroid C-cell tumors seen in rodents, and warn about pancreatitis, gallbladder disease, kidney injury from dehydration, severe stomach reactions, allergic reactions and low blood sugar with insulin or sulfonylureas. In Wegovy weight-loss trials, severe stomach side effects occurred in 4.1% of adults vs 0.9% on placebo.

The short version

The most common side effect is nausea: 44% of adults on Wegovy 2.4 mg vs 16% on placebo, and 25–29% on Zepbound vs 8% on placebo, in the trials behind the US labels.^1,2
Stomach side effects bunch up while the dose is being raised. On semaglutide, a typical nausea episode lasted about 8 days; constipation lasted longer.⁵
Serious problems such as pancreatitis, gallbladder disease and kidney injury from dehydration are uncommon but listed in every label. Severe stomach pain, signs of an allergic reaction or being unable to keep fluids down need prompt medical care.^1–4

Ozempic and Wegovy are both semaglutide. Mounjaro and Zepbound are both tirzepatide. Ozempic and Mounjaro are approved for type 2 diabetes; Wegovy and Zepbound for weight management and other uses. If you are not sure which is which, see Ozempic vs Wegovy vs Mounjaro vs Zepbound.

What are the most common side effects?

Section 6.1 of each US label lists the side effects reported more often on the drug than on placebo in its main trials. The table shows those numbers side by side.

Share of trial participants reporting each side effect, drug vs placebo. Wegovy and Zepbound: adults with obesity or overweight, up to 68 and 72 weeks. Ozempic and Mounjaro: adults with type 2 diabetes. Ranges cover the doses tested; Ozempic figures are rounded. "Not listed" means below the label's cutoff for its table (5% for Ozempic and Mounjaro). Sources: section 6.1 of each US label, 2026 versions.^1–4
Side effect	Wegovy 2.4 mg	Zepbound 5–15 mg	Ozempic 0.5–1 mg	Mounjaro 5–15 mg
Nausea	44% vs 16%	25–29% vs 8%	16–20% vs 6%	12–18% vs 4%
Diarrhea	30% vs 16%	19–23% vs 8%	8.5–8.8% vs 1.9%	12–17% vs 9%
Vomiting	24% vs 6%	8–13% vs 2%	5–9% vs 2%	5–9% vs 2%
Constipation	24% vs 11%	11–17% vs 5%	3–5% vs 1.5%	6–7% vs 1%
Abdominal pain	20% vs 10%	9–10% vs 5%	6–7% vs 5%	5–6% vs 4%
Indigestion (dyspepsia)	9% vs 3%	9–10% vs 4%	3–4% vs 2%	5–8% vs 3%
Burping (eructation)	7% vs <1%	4–5% vs 1%	1–3% vs 0%	2.5–3.3% vs 0.4%
Headache	14% vs 10%	not listed	not listed	not listed
Fatigue	11% vs 5%	5–7% vs 3%	not listed	not listed
Dizziness	8% vs 4%	4–5% vs 2%	not listed	not listed
Hair loss	3% vs 1%	4–5% vs 1%	not listed	not listed
Injection site reactions	1.4% vs 1%	6–8% vs 2%	not listed	not listed

The labels warn that rates from different trials cannot be compared directly. The Ozempic and Mounjaro trials enrolled people with type 2 diabetes and had shorter average treatment (about 33 and 37 weeks), and the Ozempic doses were lower. That is one reason their numbers look smaller. For a head-to-head view, see semaglutide vs tirzepatide.

A few other points from the labels:

Overall stomach side effects were reported by 73% of adults on Wegovy injection vs 47% on placebo, and by 56% on each Zepbound dose vs 30% on placebo.^1,2
Wegovy pill (25 mg tablet): the label says the types and frequency of common side effects were similar to the injection.¹
Wegovy 7.2 mg: nausea was 39% vs 13% on placebo. Dysesthesia, meaning altered or painful skin sensations, was reported by 22% vs 6% on Wegovy 2.4 mg.¹ See Wegovy 7.2 mg.
Mounjaro also lists decreased appetite, 5–11% vs 1% on placebo.⁴

Our detailed guides: nausea and stomach side effects, constipation, diarrhea and sulfur burps, fatigue, hair loss, injection site reactions and "Ozempic face" and loose skin.

Illustration of simple wellbeing icons in a row.

How long do the side effects last?

The best data come from a pooled analysis of the STEP 1, 2 and 3 trials: 2,117 adults with overweight or obesity on semaglutide 2.4 mg and 1,262 on placebo for 68 weeks. Stomach side effects peaked around week 20, near the end of the dose increases, and then fell. Nausea showed the biggest drop.⁵

8 daysmedian length of a nausea episode on semaglutide 2.4 mg, STEP 1–3

3 daysmedian length of a diarrhea episode (vomiting: 2 days)

47 daysmedian length of constipation, vs 35 days on placebo

The Zepbound and Mounjaro labels say most nausea, vomiting and diarrhea happened during dose escalation and decreased over time.^2,4 Across the four SURMOUNT trials, 1.0% to 10.5% of people on tirzepatide stopped because of stomach side effects.⁶ On Wegovy, 4.3% of adults stopped for this reason vs 0.7% on placebo.¹

What are the serious side effects and warnings?

These come from the boxed warning and section 5 of the US labels. They are the labels' warnings, summarized in plain words, not advice for any one person.

Boxed warning: thyroid C-cell tumors. Semaglutide and tirzepatide caused these tumors in rodents. Whether they do in humans is unknown. The labels say not to use these medicines if you or a family member have had medullary thyroid cancer, or if you have MEN 2 syndrome. Signs to report include a lump in the neck, trouble swallowing, shortness of breath or lasting hoarseness.^1–4 See GLP-1 and thyroid cancer.
Pancreatitis. In Wegovy weight-loss trials, confirmed acute pancreatitis occurred at 0.2 cases per 100 patient-years vs under 0.1 on placebo. The labels describe the main sign as severe, lasting stomach pain that may spread to the back.¹
Gallbladder disease. Gallstones were reported in 1.6% of adults on Wegovy vs 0.7% on placebo. On Zepbound, gallbladder inflammation (cholecystitis) occurred in 0.7% vs 0.2%.^1,2 See gallbladder and pancreatitis.
Severe stomach reactions. Reported in 4.1% of adults on Wegovy injection vs 0.9% on placebo. Wegovy is not recommended in severe gastroparesis (a stomach that empties very slowly). After approval, reports have included bowel blockage (ileus) and severe constipation.¹
Kidney injury from dehydration. Mostly in people who had vomiting or diarrhea and lost fluids.^1,2
Low blood sugar, mainly when used with insulin or a sulfonylurea.^1–4
Allergic reactions, including rare anaphylaxis and swelling of the face or throat (angioedema).^1,2
Diabetic eye disease. In a 2-year trial in adults with type 2 diabetes, diabetic retinopathy complications occurred in 3% on semaglutide vs 1.8% on placebo, with a larger rise in people who already had retinopathy.¹ A separate rare eye condition, NAION, is not in the US labels we checked; see GLP-1 and vision loss (NAION).
Heart rate. Resting heart rate rose by 1 to 4 beats per minute on average on Wegovy, and 1 to 3 on Zepbound.^1,2
Anesthesia. Rare reports of food being inhaled into the lungs during sedation, because these drugs slow the stomach. The labels ask patients to tell their care team before any planned procedure.^1–4 See GLP-1 before surgery.

Mood. The Wegovy and Zepbound labels removed their warning section on suicidal behavior and ideation in February 2026, according to the labels' list of recent changes.^1,2 See GLP-1 and mental health.

Get urgent care for severe stomach pain that does not go away, signs of an allergic reaction (swelling of the face or throat, trouble breathing), sudden vision changes, or vomiting or diarrhea that stops you keeping fluids down. If you have thoughts of harming yourself, call or text 988 in the US, or your local emergency number. For anything else, talk to your prescriber before changing a dose.

What is known about long-term effects?

The longest placebo-controlled data come from three trials:

Sources: Lincoff 2023, Garvey 2022, Jastreboff 2025.^7–9 All randomized, placebo-controlled trials.
Trial	Who and how long	Safety findings
SELECT (semaglutide 2.4 mg)	17,604 adults aged 45+ with heart disease and overweight or obesity, no diabetes; mean follow-up 39.8 months	16.6% stopped because of side effects vs 8.2% on placebo. Heart attack, stroke or heart death: 6.5% vs 8.0%
STEP 5 (semaglutide 2.4 mg)	304 adults with obesity or overweight, no diabetes; 104 weeks	Stomach side effects in 82.2% vs 53.9%; 3.9% vs 0.7% stopped for them. Gallbladder disorders 2.6% vs 1.3%
SURMOUNT-1 (tirzepatide 5–15 mg)	Adults with obesity and prediabetes; 176 weeks	Stomach side effects were mostly mild to moderate and mainly in the first 20 weeks. No new safety signals

SELECT collected only serious side effects, those that led people to stop, and a few of special interest, so it says little about mild ones.¹ Placebo-controlled data beyond about three to four years are limited, so rarer or slower effects rely on observational studies. See long-term results and the SELECT trial.

Are side effects different for women?

Most people in these trials were women: 71% in the Wegovy weight trials and about 63% in the Zepbound trials.^1,2 The labels and trials report a few differences:

Hair loss was mostly reported by women. On Zepbound: 7.1% of women vs 0.5% of men (placebo 1.3% vs 0%). On Wegovy 2.4 mg: 4% vs 0.9% (placebo 2% vs 0). The labels link it to weight loss.^1,2
Fractures. In SELECT, hip and pelvis fractures were more common on Wegovy than placebo in women: 1% vs 0.2%. The same was true in people aged 75 and older.¹
Stomach side effects. In SURMOUNT-1, women made up 76% of the participants who reported nausea, vomiting or diarrhea but 63% of those who did not (all study groups combined). The authors did not formally test this difference.⁶
Birth control. The Zepbound and Mounjaro labels advise people on birth control pills to switch to a non-oral method, or add a barrier method, for 4 weeks after starting and after each dose increase.^2,4
Pregnancy. The Wegovy (for weight or heart risk) and Zepbound labels say to stop when pregnancy is recognized. The Wegovy and Ozempic labels say to stop at least 2 months before a planned pregnancy, because semaglutide takes a long time to leave the body. The Ozempic and Mounjaro labels note that animal studies suggest possible harm to a fetus.^1–4

For details, see GLP-1, birth control and pregnancy and GLP-1 and menopause. Questions about pregnancy plans or contraception belong with your care team.

Common questions

What are the most common side effects of Ozempic, Wegovy and Zepbound?