Wegovy
Wegovy side effects: what's common and what's not
6 min read · Updated August 2026 · Reviewed by the Miva clinical team
Wegovy contains semaglutide, a GLP-1 receptor agonist. It slows stomach emptying and reduces appetite signals — which is also the source of most of its side effects.
Around two-thirds of people report at least one gastrointestinal side effect at some point, most often early in treatment or just after a dose increase.
Common side effects
- Nausea — the most frequently reported effect
- Diarrhoea, constipation or both at different times
- Vomiting, usually if you eat past the point of fullness
- Reflux, burping and bloating
- Headache and tiredness
- Dizziness, often related to eating and drinking less
- Injection site reactions
Managing them day to day
Most people find side effects manageable with small changes to how and what they eat.
- Eat slowly, in smaller portions, and stop when full rather than when the plate is empty
- Go easy on fried, very fatty and very sweet foods around injection day
- Drink fluids steadily — dehydration makes nausea and headaches worse
- Prioritise protein and add resistance exercise to protect muscle mass
- Treat constipation early with fibre, fluid and movement
- If a dose is too much, ask about holding it rather than pushing through
When to get medical help
- Severe ongoing abdominal pain, possibly radiating to the back — possible pancreatitis, seek urgent care
- Gallbladder symptoms: upper right abdominal pain, fever, jaundice
- Vomiting or diarrhoea you can't keep on top of, or signs of dehydration
- Rapid heartbeat, fainting, or severe dizziness
- Changes in vision if you have type 2 diabetes and diabetic retinopathy
- Allergic reaction: rash, facial or throat swelling, breathing difficulty — call 911
What about mood and mental health?
Report any new or worsening low mood, anxiety or thoughts of self-harm to a clinician promptly. Wegovy isn't suitable if you have a current or past eating disorder, and your assessment will ask about this.
Frequently asked questions
Does Wegovy make you tired?
Tiredness is commonly reported, particularly early on. It's usually linked to eating substantially less rather than the drug itself. Adequate protein, fluids and a steadier rate of weight loss generally help; persistent fatigue should be reviewed, as it can have other causes.
How long do Wegovy side effects last?
Typically days to a few weeks after starting or increasing a dose, easing as your body adjusts. Side effects that worsen over time or prevent you eating and drinking normally need a clinical review.
Is Wegovy safe?
Wegovy is approved by Health Canada for weight management in eligible adults and has been studied in large clinical trials. Safety depends on your individual history, which is why a licensed clinician reviews your assessment before prescribing.
Mounjaro (tirzepatide) and Wegovy (semaglutide) are prescription-only medicines in Canada. This page is general information, not medical advice — a Canadian-licensed clinician reviews every assessment and decides whether treatment is suitable for you.
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