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The most common semaglutide side effects are digestive: nausea, diarrhea, vomiting, constipation and stomach pain. The U.S. prescribing information for Ozempic, Wegovy (injection and pill) and Rybelsus says these effects are most frequent while the dose is being increased. Serious but less common risks include pancreatitis, gallbladder disease, kidney injury from dehydration, serious allergic reactions and diabetic eye complications, and every semaglutide product carries a boxed warning about thyroid C-cell tumors. This guide pulls the figures from the current labels and explains what changed in 2025 and 2026.
Peptide Labs does not sell semaglutide or any prescription drug. This article is general information, not medical advice. If you take semaglutide and have symptoms, contact your prescriber or pharmacist.
Key Takeaways
- Nausea affected 44% of adults on Wegovy injection in weight trials, versus 16% on placebo.
- Diabetes doses cause fewer side effects on average: nausea was about 16% to 20% on Ozempic.
- Most digestive side effects happen during dose increases.
- The FDA removed Wegovy's suicidal-thoughts warning in January 2026.
- European and UK regulators list a rare optic nerve condition (NAION); U.S. labels did not as of September 2026.
Most common semaglutide side effects
Semaglutide is sold as Ozempic (weekly injection for type 2 diabetes), Rybelsus (daily tablet for type 2 diabetes) and Wegovy (weekly injection or daily pill for weight management and cardiovascular risk reduction). Weight-management doses are higher, and so are side effect rates. The table shows placebo rates and the rates on semaglutide from each label’s main table.
| Side effect | Wegovy injection trials: placebo | Wegovy injection trials: semaglutide | Ozempic trials: placebo | Ozempic trials: semaglutide | Rybelsus trials: placebo | Rybelsus trials: semaglutide |
|---|---|---|---|---|---|---|
| Nausea | 16% | 44% | 6.1% | 15.8-20.3% | 6% | 11-20% |
| Diarrhea | 16% | 30% | 1.9% | 8.5-8.8% | 4% | 9-10% |
| Vomiting | 6% | 24% | 2.3% | 5-9.2% | 3% | 6-8% |
| Constipation | 11% | 24% | 1.5% | 3.1-5% | 2% | 5-6% |
| Stomach (abdominal) pain | 10% | 20% | 4.6% | 5.7-7.3% | 4% | 10-11% |
| Headache | 10% | 14% | Not listed | Not listed | Not listed | Not listed |
| Fatigue | 5% | 11% | Not listed | Not listed | Not listed | Not listed |
| Indigestion (dyspepsia) | 3% | 9% | 1.9% | 2.7-3.5% | Not listed | Not listed |
| Dizziness | 4% | 8% | Not listed | Not listed | Not listed | Not listed |
| Decreased appetite | Not listed | Not listed | Not listed | Not listed | 1% | 6-9% |
| Hair loss | 1% | 3% | Not listed | Not listed | Not listed | Not listed |
Ranges cover the two diabetes doses in each diabetes label. The Wegovy figures come from three trials in 2,116 adults treated for up to 68 weeks. For the Wegovy pill, the label says the types and frequency of common side effects were similar to the injection; in the OASIS 4 trial, 74.0% reported digestive side effects versus 42.2% on placebo. At the higher 7.2 mg weekly dose (Wegovy HD) now on the label, nausea was reported by 39% and vomiting by 22%. Rates from different trials cannot be compared directly.
When digestive side effects tend to happen
Every semaglutide label says the majority of nausea, vomiting and diarrhea reports occurred during dose escalation, which is why treatment starts low and is increased in steps. In the Wegovy injection weight trials, 73% of people reported digestive side effects versus 47% on placebo, severe ones occurred in 4.1% versus 0.9%, and 4.3% stopped treatment because of them versus 0.7%. With Ozempic, digestive side effects affected 32.7% to 36.4% versus 15.3% on placebo; with Rybelsus, 32% to 41% versus 21%.
Serious warnings on semaglutide labels
- Boxed warning. Semaglutide caused thyroid C-cell tumors in rodents; whether it does in humans is unknown. It is not for people with a personal or family history of medullary thyroid carcinoma or MEN 2.
- Pancreatitis. Discontinue if pancreatitis is suspected. Post-approval reports include necrotizing pancreatitis, sometimes fatal.
- Gallbladder disease. Gallstones were reported in 1.6% on Wegovy injection versus 0.7% on placebo, and in 2.5% on the Wegovy pill versus 1%.
- Low blood sugar when combined with insulin or a sulfonylurea.
- Kidney injury from dehydration caused by vomiting or diarrhea.
- Severe digestive reactions. A section added in October 2025 says semaglutide is not recommended for people with severe gastroparesis.
- Serious allergic reactions, including anaphylaxis and angioedema.
- Diabetic retinopathy complications. In a two-year trial in type 2 diabetes, complications occurred in 3% on semaglutide versus 1.8% on placebo, and in 8.2% versus 5.2% among people with existing retinopathy.
- Anesthesia. Stomach contents entering the lungs has been reported during surgery or deep sedation, so patients should tell their care team beforehand.
- Wegovy only: increased heart rate; in its cardiovascular trial, more hip and pelvis fractures in women (1% vs 0.2%) and in people 75 and older (2.4% vs 0.6%).
Semaglutide label changes in 2025 and 2026
Several changes are worth knowing if you read older articles:
- Severe gastrointestinal reactions (October 2025). Ozempic, Wegovy and Rybelsus labels gained a dedicated warning.
- Wegovy pill (December 2025). The tablet was added to the Wegovy label. See our Wegovy pill guide.
- Suicidal thoughts warning removed (January 2026). On January 13, 2026, the FDA asked for this warning to be removed from Wegovy, Zepbound and Saxenda after finding no increased risk. The FDA still advises reporting new or worsening depression or mood changes.
- Higher dose (2026). Wegovy HD 7.2 mg appears on the 2026 labels. Altered skin sensations (dysesthesia) were reported in 22% at that dose, versus 6% at 2.4 mg and none on placebo; with the pill, 5% versus none.
- Shared pens (June 2026). The multi-dose Wegovy FlexTouch pen must never be shared.
NAION: what regulators have said
Non-arteritic anterior ischemic optic neuropathy (NAION) is a rare condition in which reduced blood flow damages the optic nerve and can cause sudden vision loss, usually in one eye. In June 2025 the European Medicines Agency’s safety committee concluded that NAION is a very rare side effect of semaglutide, affecting up to 1 in 10,000 people, and recommended updating European product information. The UK’s MHRA followed with a safety update on February 5, 2026, advising urgent eye assessment for sudden vision loss and stopping semaglutide if NAION is confirmed. As of September 2026, the U.S. labels we checked (Ozempic, May 2026; Rybelsus, January 2026; Wegovy, June 2026) do not list NAION. They do tell people with type 2 diabetes to report vision changes. Anyone with sudden vision loss should get urgent medical care.
Medicines, pregnancy and the pill rules
Semaglutide slows stomach emptying, which can affect how other oral medicines are absorbed, so the labels advise extra monitoring for medicines that need precise blood levels. Unlike tirzepatide, semaglutide labels do not advise changing birth control pills. The labels say to stop semaglutide at least 2 months before a planned pregnancy because it stays in the body for weeks, and Wegovy should be stopped when pregnancy is recognized. The tablets, Rybelsus and the Wegovy pill, come with specific empty-stomach instructions that affect how well they are absorbed.
What the labels tell patients to report
The Medication Guides ask patients to contact a healthcare provider about a lump or swelling in the neck, hoarseness, trouble swallowing or shortness of breath; severe stomach pain that will not go away; symptoms of gallbladder problems such as upper stomach pain, fever or yellowing of the skin or eyes; nausea, vomiting or diarrhea that could lead to dehydration; signs of a serious allergic reaction; vision changes in type 2 diabetes; and any planned surgery. For how these risks compare with tirzepatide, see tirzepatide side effects and semaglutide vs tirzepatide. Our semaglutide profile covers the molecule, and the older daily GLP-1 drug liraglutide shares most of these warnings.
Frequently Asked Questions
What are the most common side effects of semaglutide?
Nausea, diarrhea, vomiting, constipation and stomach pain. In Wegovy’s weight trials, nausea affected 44% of adults versus 16% on placebo; at Ozempic’s diabetes doses it affected 16% to 20%.
How long do semaglutide side effects last?
The labels say most nausea, vomiting and diarrhea occurred during dose increases. Symptoms that are severe or do not go away should be reported to a healthcare provider.
Are Wegovy pill side effects different from the injection?
The label says the types and frequency of common side effects were similar. Altered skin sensations were reported in 5% on the pill versus none on placebo.
Does semaglutide cause vision problems?
European and UK regulators list NAION, a rare optic nerve condition, as a very rare side effect. U.S. labels did not list it as of September 2026, but they warn about diabetic eye complications. Sudden vision loss needs urgent care.
Is there still a suicide warning on Wegovy?
No. The FDA asked for it to be removed in January 2026 after its review found no increased risk. The FDA still advises telling a healthcare professional about mood changes.
Does semaglutide cause hair loss?
Hair loss was reported in 3% on Wegovy injection versus 1% on placebo, more often in women. The label links it to weight reduction.
This article is general information, not medical advice. Peptide Labs does not sell prescription drugs, including any product named here. Read the Medication Guide that comes with a prescription, and ask a pharmacist or prescriber how this information applies to you.
Last reviewed September 2026.
Related guides: Wegovy Side Effects: Injection, Pill, Teens and Wegovy HD, Ozempic Face: What It Is and What the Evidence Says, Wegovy vs Ozempic: Same Semaglutide, Different Labels, Liraglutide vs Semaglutide: Daily vs Weekly GLP-1 Drugs Compared, GLP-1 Side Effects: What Every GLP-1 Drug Label Warns About, Zepbound and Alcohol: What GLP-1 Labels and Research Say, Ozempic Constipation: Why It Happens and When to Get Help, Ozempic Nausea: How Long It Lasts and What Helps, Ozempic Thyroid Cancer Risk: The Boxed Warning Explained, Ozempic and Pregnancy: What the Labels Say, Ozempic Blindness and Eye Risks: What the NAION Data Show, Ozempic Rash and Injection Site Reactions: Label Facts, Ozempic Lawsuit: What the Court Records Show in 2026.