Short answer: In the label's weight-loss trials of the 2.4 mg Wegovy injection, nausea was the most common side effect: 44% on Wegovy against 16% on placebo. Diarrhea (30% vs 16%), vomiting (24% vs 6%) and constipation (24% vs 11%) followed. These were reported most often while the dose was being raised. The label carries a boxed warning about thyroid C-cell tumors seen in rodents.
What Wegovy is approved for: The label says Wegovy injection is approved, with a reduced-calorie diet and more physical activity, to lower the risk of major heart events in adults with heart disease and obesity or overweight, to reduce excess weight and keep it off in adults and children 12 and older with obesity (and adults with overweight plus a weight-related condition), and to treat MASH with moderate to advanced liver fibrosis in adults. Wegovy tablets are approved for the heart-risk and weight uses in adults.
Source
WEGOVY (semaglutide) injection, for subcutaneous use, and WEGOVY (semaglutide) tablets, for oral use, prescribing information and Medication Guide. Novo Nordisk. DailyMed, version published June 30, 2026. DailyMed setid ee06186f-2aa3-4990-a760-757579d8f77b
WARNING: RISK OF THYROID C-CELL TUMORS
In rodents, semaglutide caused thyroid C-cell tumors, and it is not known whether Wegovy causes these tumors, including medullary thyroid carcinoma (MTC), in people. Wegovy must not be used by people with a personal or family history of MTC or with Multiple Endocrine Neoplasia syndrome type 2 (MEN 2). The label lists a lump in the neck, trouble swallowing, shortness of breath and lasting hoarseness as possible thyroid tumor symptoms.
These are the label's own numbers from the Adverse Reactions section. Where the label compares with placebo (a dummy treatment), both columns are shown, so you can see how much more often a reaction happened on Wegovy.
| Adverse reaction | Placebo N=1,261 % | Wegovy Injection (2.4 mg Once Weekly) 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 |
| Eructation | <1 | 7 |
| Hypoglycemia in T2DM | 2 | 6 |
| Flatulence | 4 | 6 |
| Gastroenteritis | 4 | 6 |
| Gastroesophageal Reflux Disease | 3 | 5 |
| Gastritis | 1 | 4 |
| Gastroenteritis Viral | 3 | 4 |
| Hair Loss | 1 | 3 |
| Dysesthesia | 1 | 2 |
Three placebo-controlled trials in 2,116 adults with obesity or overweight who took Wegovy 2.4 mg injection for up to 68 weeks, plus a 7-week follow-up off the drug. Hypoglycemia in T2DM is blood sugar below 54 mg/dL in people with type 2 diabetes not on insulin (Study 3).
| Adverse reaction | Placebo N=303 % | Wegovy Injection (2.4 mg Once Weekly) N=304 % | Wegovy Injection (7.2 mg Once Weekly) N=1,311 % |
|---|---|---|---|
| Nausea | 13 | 35 | 39 |
| Vomiting | 6 | 16 | 22 |
| Dysesthesia | 0 | 6 | 22 |
| Constipation | 8 | 19 | 20 |
| Abdominal pain | 7 | 9 | 12 |
| Fatigue | 5 | 9 | 11 |
| Headache | 7 | 8 | 9 |
| Dizziness | 1 | 5 | 6 |
| Hair loss | 1 | 3 | 6 |
| Flatulence | 2 | 2 | 4 |
Two 72-week placebo-controlled trials (Study 8 and Study 9) in adults with obesity (BMI ≥30 kg/m2): 1,311 on Wegovy 7.2 mg, 304 on 2.4 mg and 303 on placebo. Dysesthesia covers altered skin sensations such as burning, tingling or sensitive skin.
Stopping treatment because of side effects: 6.8% on Wegovy 2.4 mg injection and 3.2% on placebo. The top reasons were nausea (1.8% vs 0.2%), vomiting (1.2% vs 0%) and diarrhea (0.7% vs 0.1%).
Stomach and gut side effects overall in adult weight-loss trials: 73% on Wegovy injection and 47% on placebo, with severe reactions in 4.1% and 0.9%. In the 12-and-older trial: 62% and 42%.
On Wegovy 25 mg tablets, 6.9% stopped because of side effects versus 5.9% on placebo; dysesthesia was reported in 5% on tablets and no one on placebo.
Hair loss: 3.3% on 2.4 mg (4% of women, 0.9% of men) versus 1% on placebo; 5.8% on 7.2 mg (8.4% of women, 0.2% of men).
Injection site reactions: 1.4% on Wegovy and 1% on placebo. Low blood pressure reactions: 1.3% vs 0.4%; fainting: 0.8% vs 0.2%.
The Warnings and Precautions part of the label lists these. Each line gives the label's heading and what it means in plain words.
Risk of thyroid C-cell tumors. Semaglutide caused thyroid C-cell tumors in mice and rats; whether this happens in people is unknown. People with a personal or family history of MTC or with MEN 2 must not use Wegovy.
Acute pancreatitis. Inflammation of the pancreas, including fatal cases, has been seen with GLP-1 drugs including Wegovy. The label says to stop Wegovy if pancreatitis is suspected.
Gallbladder disease. Gallstones were reported in 1.6% on Wegovy injection vs 0.7% on placebo, and 2.5% on tablets vs 1%. In children 12 and older, gallstones were reported in 3.8% vs 0%. The label says the excess was seen even after accounting for weight loss.
Low blood sugar. Wegovy lowers blood sugar and can cause low blood sugar, with higher risk alongside insulin or a sulfonylurea. In people with diabetes the label says to check blood sugar before and during treatment.
Kidney injury from fluid loss. Acute kidney injury, sometimes needing dialysis, has been reported, mostly in people who became dehydrated from nausea, vomiting or diarrhea. The label says to monitor kidney function in these people, especially when starting or raising the dose.
Severe stomach and gut side effects. Severe stomach and gut side effects were reported in 4.1% on Wegovy injection vs 0.9% on placebo, and 2% on tablets vs 0%. Wegovy is not recommended in people with severe gastroparesis.
Allergic reactions. Serious allergic reactions such as anaphylaxis and angioedema have been reported. The label says to stop Wegovy if they occur.
Diabetic eye complications in type 2 diabetes. In a trial of adults with type 2 diabetes, diabetic retinopathy was reported by 4% on Wegovy injection and 2.7% on placebo. People with a history of diabetic retinopathy should be monitored, the label says.
Heart rate increase. Resting heart rate rose by a mean of 1 to 4 beats per minute in adults. The label says to check heart rate regularly and to stop Wegovy if resting heart rate stays raised.
Food or liquid in the lungs during anesthesia. Wegovy slows stomach emptying. Rare reports describe food entering the lungs during procedures with general anesthesia or deep sedation. The label says to tell your providers you take Wegovy before any planned procedure.
Never share a FlexTouch pen. The Wegovy FlexTouch pen must never be shared between people, even if the needle is changed, because of the risk of passing on blood-borne infections.
From the Medication Guide that comes with Wegovy:
Dose Track has a side-effect log. Each entry records the symptom, a severity (none, mild, moderate, severe or life-threatening), the date and an optional note, and can be tied to a specific dose or logged on its own. The history screen shows what you logged over time, which makes it easier to tell your prescriber when a reaction started and whether it is easing. The app records what you enter; it does not judge whether a symptom is serious. For anything on the label's call-your-doctor list, call your doctor.
This page is what the FDA label says, in plain words. It is not medical advice. Follow your prescriber, and ask them or your pharmacist about anything here.