Semaglutide side effects, from the Wegovy label
On Wegovy 2.4 mg, 44% had nausea vs 16% on placebo, and 73% had a GI effect. Label rates for each common side effect, the serious warnings and the gaps.
Key takeaways
- In three 68-week trials (2,116 adults on 2.4 mg), 73% on Wegovy reported a gastrointestinal side effect vs 47% on placebo.
- Nausea 44%, diarrhea 30%, vomiting 24%, constipation 24% (placebo 16%, 16%, 6%, 11%).
- 6.8% stopped Wegovy because of side effects vs 3.2% on placebo; 4.3% stopped for GI reasons.
- Altered skin sensation (dysesthesia) rose with dose and is more frequent at the 7.2 mg Wegovy HD dose.
Semaglutide is the active ingredient in Wegovy (weight management, cardiovascular risk reduction, MASH), Ozempic (type 2 diabetes) and Rybelsus (oral, diabetes). The figures below are from the Wegovy prescribing information: three placebo-controlled trials in which 2,116 adults took 2.4 mg weekly for up to 68 weeks.
Common side effects
| Side effect | Placebo (n = 1,261) | Wegovy 2.4 mg (n = 2,116) |
|---|---|---|
| Nausea | 16% | 44% |
| Diarrhea | 16% | 30% |
| Vomiting | 6% | 24% |
| Constipation | 11% | 24% |
| Abdominal pain | 10% | 20% |
| Headache | 10% | 14% |
| Fatigue | 5% | 11% |
| Dyspepsia | 3% | 9% |
| Dizziness | 4% | 8% |
| Abdominal distension | 5% | 7% |
| Burping | under 1% | 7% |
| Low blood sugar (with type 2 diabetes) | 2% | 6% |
| Flatulence | 4% | 6% |
| Acid reflux (GERD) | 3% | 5% |
| Hair loss | 1% | 3% |
| Altered skin sensation | 1% | 2% |
Source: Wegovy label, Table 3.
Gastrointestinal effects in context
Seventy-three percent of people on Wegovy reported at least one GI reaction, against 47% on placebo, and severe GI reactions occurred in 4.1% versus 0.9%. The label notes they were most frequent while the dose was being raised. 4.3% of Wegovy patients stopped because of a GI reaction (0.7% on placebo); overall, 6.8% stopped for any side effect (3.2% on placebo), most often nausea, vomiting or diarrhea.
The escalation itself is in our semaglutide dosage guide and on the Wegovy label schedule page.
Higher doses and skin sensation
Dysesthesia, which includes tingling, skin pain and burning sensations, increased with dose and blood levels, and was reported more often with the 7.2 mg dose approved in March 2026 as Wegovy HD. Background: Wegovy HD 7.2 mg.
Serious warnings
As with all GLP-1 medicines, the label warns about thyroid C-cell tumors (seen in rodents; human relevance unknown), pancreatitis, gallbladder disease, low blood sugar when combined with insulin or sulfonylureas, kidney injury from dehydration, allergic reactions, diabetic retinopathy complications in people with type 2 diabetes, and aspiration during anesthesia because of slowed stomach emptying.
Semaglutide vs tirzepatide
The Zepbound label reports nausea in 25–29% of tirzepatide users against 8% on placebo. The trials differed in design and population, so the labels cannot rank the two drugs; a head-to-head comparison is on tirzepatide vs semaglutide.
Compounded and research semaglutide
These rates describe the manufactured product. Compounded injections, sublingual drops and research vials have no trial data of their own, and FDA has received reports of dosing errors with compounded semaglutide, often from confusion between mg, mL and syringe units. If you are checking a conversion, use the semaglutide units converter. Price data for research vials: semaglutide prices per mg.
This summary is reference material, not medical advice. Report side effects to your prescriber or FDA MedWatch.
What the evidence does not show
- Side-effect rates for compounded, sublingual or research semaglutide: no trial has measured them.
- Rates for Ozempic at diabetes doses, which come from a different label.
Frequently asked questions
What are the most common side effects of semaglutide?
For Wegovy 2.4 mg weekly: nausea (44%), diarrhea (30%), vomiting (24%), constipation (24%), abdominal pain (20%), headache (14%), fatigue (11%), dyspepsia (9%) and dizziness (8%), each more common than on placebo.
When are semaglutide side effects worst?
The label says GI reactions were reported most often during dose escalation, which is why the dose rises in four-week steps from 0.25 mg.
Does semaglutide cause hair loss?
Hair loss was reported in 3% of Wegovy users vs 1% on placebo in the weight trials.
Is semaglutide or tirzepatide worse for nausea?
Label figures come from different trials, so they are not a head-to-head comparison: nausea was 44% on Wegovy 2.4 mg and 25–29% on Zepbound 5–15 mg, against placebo rates of 16% and 8%.
Why do semaglutide labels warn about thyroid tumors?
Semaglutide caused thyroid C-cell tumors in rodents. Whether it does in people is unknown, so it is contraindicated with a personal or family history of medullary thyroid carcinoma or MEN 2.
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