The most common side effects of Wegovy are gastrointestinal — nausea, diarrhea, constipation, and vomiting — and they typically appear or worsen each time your dose is increased during the 16-week titration period. About 44 percent of trial participants reported nausea at some point, but most found it manageable and most successfully reached the 2.4 mg maintenance dose. Discontinuation from side effects was about 7 percent in the STEP trials. Below is a more complete picture of what to expect.
Most Common Side Effects (Gastrointestinal)
These are direct consequences of how Wegovy works. The drug slows stomach emptying, increases satiety signaling, and acts on receptors in the gut and brain. The body usually adapts over time.
| Side Effect | STEP-1 Trial Incidence | Typical Pattern |
|---|---|---|
| Nausea | 44.2% | Peaks 1-2 days after each dose increase, eases over weeks |
| Diarrhea | 31.5% | Often intermittent; usually mild to moderate |
| Vomiting | 24.8% | Less common than nausea; can cause dehydration |
| Constipation | 23.4% | From slowed gut motility; manageable with fiber + fluids |
| Abdominal pain | 20.4% | Usually mild; persistent severe pain needs evaluation |
| Headache | 14.0% | Often related to dehydration or low blood sugar |
| Fatigue | 11.0% | From reduced calorie intake; usually improves over time |
| Heartburn / GERD | 9.1% | From slowed stomach emptying |
Practical Management of GI Symptoms
For nausea: eat smaller meals more frequently, avoid greasy or spicy food, eat slowly, stay upright for at least 30 minutes after eating, drink ginger or peppermint tea, and stay hydrated. Bland foods (toast, rice, bananas) often help during peak nausea days.
For constipation: increase fiber gradually (sudden fiber increases worsen GI symptoms on Wegovy), drink at least 8 cups of fluid daily, walk after meals, and use over-the-counter options like polyethylene glycol if needed (ask your pharmacist first).
For diarrhea: identify and limit trigger foods (often dairy, high-fat foods, or artificial sweeteners), maintain electrolytes with oral rehydration solutions, and avoid loperamide for prolonged use without consulting your prescriber.
For vomiting: if persistent, call your prescriber — they may slow your titration schedule or hold your dose. Dehydration from vomiting can cause acute kidney injury, so don’t tough it out alone.
Serious But Less Common Side Effects
Pancreatitis. Acute pancreatitis has been reported with all GLP-1 receptor agonists. Symptoms include severe persistent upper abdominal pain (often radiating to the back), nausea, and vomiting. Stop Wegovy and seek immediate medical attention if these symptoms develop. The absolute risk is low (roughly 0.1-0.3 percent annually) but the condition can be life-threatening.
Gallbladder disease. Rapid weight loss is itself a risk factor for gallstones. Wegovy roughly doubles the rate of cholecystitis (gallbladder inflammation) compared to placebo in trials. Symptoms include right upper-quadrant pain, nausea after fatty meals, and fever. Call your prescriber for evaluation.
Acute kidney injury. Almost always secondary to dehydration from vomiting or diarrhea. Maintain hydration and report persistent GI symptoms.
Hypoglycemia. Wegovy itself rarely causes low blood sugar in people without diabetes. Risk increases substantially when combined with insulin or sulfonylureas; dose adjustments to those medications are often needed.
Increased heart rate. Wegovy increases resting heart rate by about 1-4 beats per minute on average. Usually clinically insignificant, but discuss with your prescriber if you have a history of arrhythmia.
Boxed Warning: Thyroid C-Cell Tumors
Wegovy carries an FDA boxed warning based on rodent studies showing dose-dependent and treatment-duration-dependent thyroid C-cell tumors. Whether this translates to human risk is unknown — no signal has emerged in clinical trials, but the trials are not long enough to detect rare tumors. Wegovy is contraindicated in patients with a personal or family history of medullary thyroid carcinoma (MTC) or multiple endocrine neoplasia syndrome type 2 (MEN 2).
Mental Health Considerations
The FDA has investigated reports of suicidal ideation in patients on GLP-1 drugs but has not found a causal link to date. Wegovy’s prescribing information notes the need to monitor for depression or suicidal thoughts. If you have a history of depression or suicidal ideation, discuss with your prescriber before starting and during treatment.
Hair Loss
Hair loss is reported by about 3 percent of Wegovy weight-loss trial participants versus 1 percent on placebo. This is usually telogen effluvium — temporary shedding triggered by rapid weight loss rather than a direct drug effect. Ensuring adequate protein (0.8-1.2 g/kg body weight) and micronutrient intake (iron, zinc, biotin, vitamin D) reduces risk and supports regrowth. Hair typically returns to normal density within 6-12 months after weight stabilizes.
Wegovy “Face” and Skin Changes
“Ozempic face” and similar terms describe facial volume loss from rapid weight loss. This is not a drug-specific effect — any rapid weight loss causes loss of facial fat. The change is largely cosmetic and varies by individual. Some users seek dermatologic interventions (filler, etc.) to address it; many adapt over time as the face stabilizes at the new weight.
When to Call Your Prescriber
Contact your prescriber promptly for:
- Severe persistent abdominal pain (especially radiating to the back)
- Persistent vomiting preventing fluid intake
- Signs of severe dehydration (dizziness, dark urine, confusion)
- Signs of allergic reaction (rash, swelling, breathing difficulty)
- Vision changes (rare but serious in patients with diabetic retinopathy)
- Yellowing of skin or eyes
The Bottom Line
Most Wegovy side effects are gastrointestinal, dose-dependent, and improve as your body adapts. Slow titration, smaller meals, hydration, and patience handle most symptoms. Serious side effects (pancreatitis, gallbladder disease, kidney injury) are uncommon but require prompt medical evaluation. The boxed warning about thyroid tumors is based on rodent data; human risk is unknown. About 7 percent of trial participants discontinued Wegovy from side effects, meaning the large majority tolerated treatment successfully. Consult your prescriber about any persistent or severe symptoms. For more on weight-loss treatment options, see our hub.
