Short answer: In the label's placebo-controlled trials in adults, nausea was the most common side effect of Saxenda: 39.3% against 13.8% on placebo. Diarrhea (20.9% vs 9.9%), constipation (19.4% vs 8.5%) and vomiting (15.7% vs 3.9%) followed. The label says nausea became less common as treatment continued. It carries a boxed warning about thyroid C-cell tumors seen in rodents.
What Saxenda is approved for: The label says Saxenda is approved, with a reduced-calorie diet and more physical activity, to reduce excess body weight and keep it off long term in adults and children 12 and older with obesity and a body weight over 60 kg, and in adults with overweight who have at least one weight-related medical condition.
Source
SAXENDA (liraglutide) injection, for subcutaneous use, prescribing information and Medication Guide. Novo Nordisk. DailyMed, version published June 15, 2026. DailyMed setid 3946d389-0926-4f77-a708-0acb8153b143
WARNING: RISK OF THYROID C-CELL TUMORS
Liraglutide caused thyroid C-cell tumors in rats and mice, and it is not known whether Saxenda causes these tumors, including medullary thyroid carcinoma (MTC), in people. Saxenda must not be used by people with a personal or family history of MTC or with Multiple Endocrine Neoplasia syndrome type 2 (MEN 2). The label lists a lump in the neck, trouble swallowing, shortness of breath and lasting hoarseness as possible thyroid tumor symptoms.
These are the label's own numbers from the Adverse Reactions section. Where the label compares with placebo (a dummy treatment), both columns are shown, so you can see how much more often a reaction happened on Saxenda.
| Adverse reaction | Placebo N=1941 % | Saxenda N=3384 % |
|---|---|---|
| Nausea | 13.8 | 39.3 |
| Diarrhea | 9.9 | 20.9 |
| Constipation | 8.5 | 19.4 |
| Vomiting | 3.9 | 15.7 |
| Injection Site Reaction | 10.5 | 13.9 |
| Headache | 12.6 | 13.6 |
| Hypoglycemia in T2DM | 6.6 | 12.6 |
| Dyspepsia | 2.7 | 9.6 |
| Fatigue | 4.6 | 7.5 |
| Dizziness | 5 | 6.9 |
| Abdominal Pain | 3.1 | 5.4 |
| Increased Lipase | 2.2 | 5.3 |
| Upper Abdominal Pain | 2.7 | 5.1 |
| Gastroenteritis | 3.2 | 4.7 |
| Gastroesophageal Reflux Disease | 1.7 | 4.7 |
| Abdominal Distension | 3 | 4.5 |
| Eructation | 0.2 | 4.5 |
| Urinary Tract Infection | 3.1 | 4.3 |
| Flatulence | 2.5 | 4 |
| Viral Gastroenteritis | 1.6 | 2.8 |
| Insomnia | 1.7 | 2.4 |
| Dry Mouth | 1 | 2.3 |
| Asthenia | 0.8 | 2.1 |
| Anxiety | 1.6 | 2 |
Five placebo-controlled trials in 3,384 adults with overweight or obesity treated for up to 56 weeks (mean 46 weeks), alongside diet and activity counseling. Hypoglycemia in T2DM is blood sugar below 54 mg/dL in people with type 2 diabetes not on insulin (Study 2).
| Adverse reaction | Placebo N=126 % | Saxenda N=125 % |
|---|---|---|
| Nausea | 14.3 | 42.4 |
| Vomiting | 4 | 34.4 |
| Diarrhea | 14.3 | 22.4 |
| Hypoglycemia | 4 | 15.2 |
| Gastroenteritis | 4.8 | 12.8 |
| Dizziness | 3.2 | 10.4 |
| Pyrexia | 7.1 | 8 |
| Abdominal discomfort | 0.8 | 4.8 |
| Constipation | 2.4 | 4.8 |
| Dyslipidemia | 3.2 | 4.8 |
| Fatigue | 3.2 | 4.8 |
| Cough | 3.2 | 4 |
| Depression | 2.4 | 4 |
| Dyspepsia | 2.4 | 4 |
| Pain in extremity | 2.4 | 4 |
| Injection site pain | 3.2 | 3.2 |
| Flatulence | 0 | 3.2 |
| Increased Blood Creatine Kinase | 2.4 | 3.2 |
| Increased Lipase | 0.8 | 3.2 |
| Rash | 0 | 3.2 |
One 56-week placebo-controlled trial in children aged 12 and older with obesity (125 on Saxenda, 126 on placebo). Hypoglycemia here means blood sugar below 70 mg/dL with symptoms; these children did not have type 2 diabetes.
Stopping treatment because of side effects: 9.8% on Saxenda and 4.3% on placebo in adults. The top reasons were nausea (2.9% vs 0.2%), vomiting (1.7% vs less than 0.1%) and diarrhea (1.4% vs 0%).
Stomach and gut problems overall: about 68% on Saxenda and 39% on placebo, with severe reactions in 4.8% and 1.4%. 6.2% on Saxenda versus 0.8% on placebo stopped because of them.
In the trial in children 12 and older, 8% on Saxenda versus none on placebo stopped because of stomach and gut side effects, mostly vomiting (4.8%) and nausea (3.2%).
In adults with type 2 diabetes taking a sulfonylurea, blood sugar below 54 mg/dL occurred in 28.2% on Saxenda and 12.7% on placebo; severe low blood sugar occurred in 0.7% on Saxenda.
Breast cancer was reported in 0.7% of women on Saxenda versus 0.2% on placebo; the label says there were too few cases to tell whether they were related to Saxenda.
The Warnings and Precautions part of the label lists these. Each line gives the label's heading and what it means in plain words.
Risk of thyroid C-cell tumors. Liraglutide caused thyroid C-cell tumors in rats and mice, and cases of MTC have been reported after marketing. People with a personal or family history of MTC or with MEN 2 must not use Saxenda.
Acute pancreatitis. Inflammation of the pancreas, including fatal cases, has been seen with GLP-1 drugs including liraglutide. The label says to stop Saxenda if pancreatitis is suspected.
Gallbladder disease. Gallstones were reported in 2.2% on Saxenda versus 0.8% on placebo, and gallbladder inflammation in 0.8% versus 0.4%. Most people with these events needed gallbladder removal. The excess was seen even after accounting for weight loss.
Low blood sugar. Adults with type 2 diabetes on a sulfonylurea or insulin may have a higher risk of low blood sugar, and the label says to check blood sugar before and during treatment. In children without diabetes, blood sugar below 54 mg/dL occurred in 1.6% on Saxenda versus 0.8% on placebo.
Heart rate increase. Resting heart rate rose by a mean of 2 to 3 beats per minute in adults and 3 to 7 in children. The label says to check heart rate regularly and to stop Saxenda if resting heart rate stays raised.
Kidney injury from fluid loss. Acute kidney injury, sometimes needing dialysis, has been reported, mostly in people who became dehydrated from nausea, vomiting or diarrhea. The label says to monitor kidney function in these people, especially when starting or raising the dose.
Severe stomach and gut side effects. Severe stomach and gut side effects were reported in 4.8% on Saxenda against 1.4% on placebo. Saxenda is not recommended in people with severe gastroparesis.
Allergic reactions. Serious allergic reactions such as anaphylaxis and angioedema have been reported. The label says the patient should stop Saxenda and other suspect medicines and promptly seek medical advice.
Food or liquid in the lungs during anesthesia. Saxenda slows stomach emptying. Rare reports describe food entering the lungs during procedures with general anesthesia or deep sedation. The label says to tell your providers you take Saxenda before any planned procedure.
From the Medication Guide that comes with Saxenda:
Dose Track has a side-effect log. Each entry records the symptom, a severity (none, mild, moderate, severe or life-threatening), the date and an optional note, and can be tied to a specific dose or logged on its own. The history screen shows what you logged over time, which makes it easier to tell your prescriber when a reaction started and whether it is easing. The app records what you enter; it does not judge whether a symptom is serious. For anything on the label's call-your-doctor list, call your doctor.
This page is what the FDA label says, in plain words. It is not medical advice. Follow your prescriber, and ask them or your pharmacist about anything here.