The common side effects
Across Ozempic, Wegovy, Mounjaro and Saxenda, the most common side effects are similar and mostly about the gut:
- Nausea (the most common, especially early)
- Constipation
- Diarrhoea
- Reflux / indigestion
- Burping, bloating, reduced appetite
- Tiredness and occasional headaches
They're usually worst when you start or step up a dose and ease as your body adjusts — which is exactly why doses are increased slowly (see dosage & titration).
Managing nausea
- Eat smaller meals, and stop when you're comfortably full rather than “done”.
- Go easy on greasy, fried and very rich foods, which sit heavily.
- Stay hydrated; ginger or plain, bland foods can help.
- Don't rush dose increases — ask your provider to slow titration if needed.
Important
Constipation & diarrhoea
For constipation: more fibre, fluids and movement; a provider may suggest a gentle laxative. For diarrhoea: stay hydrated and keep meals simple. Both often settle as you adjust. More on eating well in diet & lifestyle.
Rare but serious risks
Less common but important risks to be aware of include:
- Pancreatitis — severe, persistent abdominal pain, often radiating to the back.
- Gallbladder problems — sometimes linked to rapid weight loss.
- Bowel obstruction (ileus) — rare; severe, ongoing abdominal pain and vomiting.
- Thyroid C-cell tumours — a caution from animal studies; these medicines are not for people with a personal/family history of medullary thyroid carcinoma or MEN 2.
- Hypoglycaemia — more likely if combined with insulin or sulfonylureas.
- Not for use in pregnancy.
This list isn't exhaustive — read the patient information leaflet and discuss your history with your provider. That's why these are prescription-only.
When to seek medical help
Red flags
Side effects can usually be managed — a registered provider can guide you
Next step