Wegovy contains semaglutide and is used for weight management in eligible people alongside a reduced-calorie diet and physical activity. For its mechanism and results, read the guide to semaglutide for weight loss. This article focuses on safety.
Commonly reported side effects
Digestive reactions are among the most frequently reported side effects, particularly at the start of treatment or after a dose increase. Reported symptoms can include the following; check the current leaflet for the frequency associated with the prescribed formulation:
- nausea;
- diarrhoea or constipation;
- vomiting;
- abdominal pain, bloating or reflux;
- fatigue, headache or dizziness.
In many cases, symptoms lessen over time, but they must not be ignored if they are severe, persistent or cause dehydration. Dietary adjustments, smaller meals and gradual dose increases are approaches commonly discussed with the doctor. Do not adjust the prescribed dose yourself.
Warning signs
Seek prompt medical advice for severe abdominal pain, repeated vomiting, inability to stay hydrated, signs of low blood glucose, an allergic reaction, pain in the upper right abdomen or new visual symptoms. These symptoms need assessment; they do not all indicate the same complication. Sudden loss of vision or rapidly worsening eyesight requires immediate medical advice. Difficulty breathing or swelling of the face or throat requires emergency help; call the local emergency number.
Who needs careful assessment before starting?
Assessment covers the contraindications and precautions in the EU product information, allergies, medical history, current treatments and plans for pregnancy. Tell the doctor about previous pancreatitis, severe digestive conditions and personal or family thyroid history.
If you have type 2 diabetes and use insulin or medicines that can cause hypoglycaemia, your treatment plan needs medical review. A rapid reduction in food intake may change your treatment requirements.
What does the doctor monitor?
- weight, waist circumference and blood pressure;
- blood glucose and HbA1c;
- blood lipids and liver function;
- digestive symptoms, tolerability and food intake;
- signs of nutritional deficiencies, particularly if appetite falls too much.
Weight-loss treatment should be part of a wider care plan. See the Wegovy treatment page and the article Wegovy vs Mounjaro.
How can you improve tolerability?
Eat smaller portions, avoid very fatty meals, stay hydrated, do not rush dose increases and discuss persistent symptoms with the doctor. If you reach a weight-loss plateau, increasing the dose is not necessarily the answer; the whole plan needs reassessment.
Medical references
- European Medicines Agency — Wegovy EPAR (EU)
- DailyMed/FDA — Wegovy prescribing information (United States)
- FDA — GLP-1 safety update of 13 January 2026 (United States)
Official information to check
EMA — current EU product information for Wegovy. For tirzepatide: EMA — Mounjaro. Discuss indications and precautions with your doctor; the EU product information is the reference for EU-authorised use.
