What are the most common Saxenda side effects?

In clinical trials the most commonly reported were nausea (about 40% of participants), diarrhoea (21%), constipation (19%) and vomiting (16%). The FDA label reports very similar figures against placebo: nausea 39.3% versus 13.8%, diarrhoea 20.9% versus 9.9%, constipation 19.4% versus 8.5% and vomiting 15.7% versus 3.9%.

What is the Saxenda boxed warning about?

Liraglutide caused thyroid C-cell tumours in rats and mice, with the risk rising at higher doses and with longer treatment. Because of that, the label carries a boxed warning and says Saxenda must not be used by anyone with a personal or family history of medullary thyroid carcinoma, or with Multiple Endocrine Neoplasia syndrome type 2.

Do I need to tell anyone about Saxenda before surgery?

Yes. The label carries a warning about food entering the lungs during general anaesthesia or deep sedation, because the drug slows stomach emptying. Tell your surgeon, anaesthetist or dentist that you take it.

What should make me call my doctor straight away?

Severe abdominal pain that may spread to your back, pain in the upper right of your abdomen with fever or yellowing skin, a lump or swelling in the neck, trouble swallowing, or vomiting and diarrhoea severe enough that you cannot stay hydrated.

Saxenda side effects: what trials show

Q: How many people stop Saxenda because of side effects?

The label reports that 9.8% of adults in the trials stopped early because of an adverse reaction, compared with 4.3% on placebo. Nausea (2.9%), vomiting (1.7%) and diarrhoea (1.4%) were the most common reasons.

What the FDA label warns about

These come from the Saxenda prescribing information published on DailyMed.

Boxed warning: risk of thyroid C-cell tumours

The label carries a boxed warning — the most serious kind. Liraglutide caused thyroid C-cell tumours in both male and female rats and mice, and the effect increased with higher doses and longer treatment.

Saxenda must not be used if you or a family member has had medullary thyroid carcinoma, or if you have Multiple Endocrine Neoplasia syndrome type 2. It is also contraindicated if you have had a serious allergic reaction to liraglutide or anything else in the injection.

Other warnings and precautions on the label:

Acute pancreatitis
Acute gallbladder disease
Low blood sugar, particularly alongside insulin or a sulfonylurea
Increased heart rate
Acute kidney injury caused by dehydration from vomiting or diarrhoea
Severe gastrointestinal reactions
Hypersensitivity reactions
Food entering the lungs during general anaesthesia or deep sedation — tell your anaesthetist you take it

The label numbers, against placebo

The FDA label reports these adult adverse reaction rates for Saxenda against placebo (n=1,941). They are close to, but not identical to, the trial figures above.

Adverse reaction rates reported on the Liraglutide FDA label, against placebo
Reaction	Saxenda (n=3,384)	Placebo
Nausea	39.3%	13.8%
Diarrhoea	20.9%	9.9%
Constipation	19.4%	8.5%
Vomiting	15.7%	3.9%
Headache	13.6%	12.6%
Indigestion	9.6%	2.7%

How many people stopped because of side effects

9.8%

of adults in the trials stopped Saxenda early because of an adverse reaction, compared with 4.3% on placebo. The most common reasons were nausea (2.9%), vomiting (1.7%) and diarrhoea (1.4%).

Rare but serious — when to call your doctor

Call your doctor immediately if you have:

Severe abdominal pain, with or without vomiting, that may spread to your back (possible pancreatitis)
Pain in the upper right of your abdomen, fever, or yellowing of the skin or eyes (possible gallbladder problems)
Shakiness, sweating, confusion or dizziness, especially if you also take insulin or a sulfonylurea (low blood sugar)
A lump or swelling in the neck, hoarseness, trouble swallowing or shortness of breath (thyroid symptoms listed on the label)
Vomiting or diarrhoea you cannot stay on top of, which can lead to dehydration and kidney injury
Swelling of the face, lips or tongue, or difficulty breathing (allergic reaction)

What actually helps

Strategies that work best, based on trial and community experience.

Smaller, slower meals

The drug slows how quickly your stomach empties. Smaller portions eaten slowly are the most commonly suggested way to reduce nausea.

Keep fluids up

The label lists dehydration from vomiting or diarrhoea as a cause of acute kidney injury. Sipping through the day matters more than drinking a lot at once.

Tell your anaesthetist

The label warns about food entering the lungs during general anaesthesia or deep sedation. Mention Saxenda before any procedure or dental sedation.

Flag other medicines

If you take insulin or a sulfonylurea, the label warns about low blood sugar. Your prescriber may adjust those doses.

When to push through vs. talk to your doctor

You can push through if...

Mild nausea that is settling week by week
You are still able to eat and drink normally
Constipation that responds to fluids and fibre
You are keeping up with fluids

Talk to your doctor if...

Severe abdominal pain, or pain that spreads to your back
Vomiting or diarrhoea you cannot keep on top of
A lump or swelling in your neck, or trouble swallowing
Symptoms of low blood sugar if you also take insulin or a sulfonylurea
Any symptom you are unsure about

Common questions

Written and maintained by one person · Built with agentic AI tools · Every number checked against the cited trial · Not medical advice

How this site is built →

Keep reading

Full Saxenda overview →Saxenda results in trials →What to expect week by week →Saxenda cost →All Saxenda clinical evidence →Nausea deep dive →

Next step most people take

Check contraindicationsWho should not take this drug Back to overviewFull profile, cost, and benefits

Built with agentic AI tools and not a substitute for medical advice

Last reviewed: September 2026

Was this page helpful?

Medical disclaimer: This website is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any treatment. Prices shown are United States self-pay or list prices and vary by insurance and country.