Saxenda is made with liraglutide. Zepbound is made with tirzepatide. Both are FDA-approved medicines for weight management. Both labels cover adults with obesity, or with overweight and a health problem linked to weight. The Saxenda label also covers children aged 12 and older who have obesity and weigh more than 60 kg (about 132 pounds). Zepbound is not approved for children. It is also approved for moderate to severe sleep apnea in adults with obesity.
Each label lists the side effects seen in that product's own placebo-controlled trials. The tables below copy those numbers. Placebo means a shot with no medicine in it. A problem in a table is not proof that the medicine caused it.
The two tables come from separate trials with different people and different lengths. The Saxenda trials lasted 32 to 56 weeks, some up to about 3 years, and 15% of the adults had type 2 diabetes. The Zepbound trials lasted up to 72 weeks. One of the two included only people with type 2 diabetes, so 25% of the adults had it. They do not come from one trial that tested Saxenda and Zepbound against each other.
The boxed warning on each label
- Saxenda (liraglutide): The Saxenda label has a boxed warning, FDA's strongest kind. Liraglutide caused thyroid C-cell tumors in rats and mice. It is not known whether it causes them in people, including medullary thyroid cancer (MTC). People with a personal or family history of MTC, or with a condition called MEN 2, must not use it. The label lists signs of a thyroid tumor to watch for: a lump in the neck, trouble swallowing, shortness of breath, or hoarseness that does not go away.
- Zepbound (tirzepatide): The Zepbound label has a boxed warning, FDA's strongest kind. Tirzepatide caused thyroid C-cell tumors in rats. It is not known whether it causes them in people, including medullary thyroid cancer (MTC). People with a personal or family history of MTC, or with a condition called MEN 2, must not use it. The label lists signs of a thyroid tumor to watch for: a lump in the neck, trouble swallowing, shortness of breath, or hoarseness that does not go away.
Stomach and bowel problems, and stopping the medicine
- Saxenda label: in the weight trials in adults, 68% on Saxenda and 39% on placebo had a stomach or bowel problem. 9.8% stopped Saxenda because of side effects, compared with 4.3% on placebo.
- Zepbound label: in the weight trials, 56% of adults on Zepbound and 30% on placebo had a stomach or bowel problem. Across the three dose groups, 4.8% to 6.7% stopped Zepbound because of side effects, compared with 3.4% on placebo.
Compare each number with its own placebo number, not with the other label.
Saxenda vs Zepbound: side effect tables
The Saxenda label lists problems in at least 2% of adults on Saxenda that were more common than on placebo. Its table here shows the ones that reached 5%. The Zepbound label lists problems in at least 2% of adults on Zepbound that were more common than on placebo. Its table here shows the 12 the label names as most common. The Zepbound middle column shows the lowest and highest share across three dose groups.
A problem missing from one table may still have happened. The Saxenda label also lists acid reflux, bloated belly, burping, gas, and trouble sleeping, among others. They are in the less common table on the liraglutide page. The Zepbound label also lists dizziness, gas, bloated belly, and low blood pressure. They are in the less common table on the tirzepatide side effects page.
Low blood sugar is only in the Saxenda table. That row comes from one trial of adults with type 2 diabetes who were not taking insulin. The Zepbound label reports it separately. In its trial of adults with type 2 diabetes, 4.2% on Zepbound and 1.3% on placebo had a blood sugar below 54 mg/dL. The Zepbound label says it can cause low blood sugar, including in adults without type 2 diabetes.
Both labels report more low blood sugar with a diabetes medicine called a sulfonylurea. Each label counts a blood sugar below 54 mg/dL in one trial of adults with type 2 diabetes.
In the Saxenda trial, among people who took a sulfonylurea, it happened to 28.2% on Saxenda and 12.7% on placebo. Among people who did not take one, it happened to 7.1% on Saxenda and 4.5% on placebo. 3 of 422 people on Saxenda needed another person's help, all taking a sulfonylurea. No one on placebo did.
In the Zepbound trial, it happened to 10.3% of people on Zepbound who took a sulfonylurea and 2.1% of those who did not. The label gives no placebo number for this split.
The two trials had different designs. In the Saxenda trial, sulfonylurea doses were cut in half at the start. So these numbers cannot be compared across the labels either.
Compare each Saxenda or Zepbound number with its own placebo number.
Saxenda label
Saxenda trials in adults with obesity or overweight 32 to 56 weeks, some up to about 3 years
Adults with obesity or overweight in 5 trials. 3,384 got Saxenda and 1,941 got placebo. 15% had type 2 diabetes. Everyone also got advice on diet and exercise.
| Reported problem | Saxenda | Placebo |
|---|---|---|
| Nausea | 39.3% | 13.8% |
| Diarrhea | 20.9% | 9.9% |
| Constipation | 19.4% | 8.5% |
| Vomiting | 15.7% | 3.9% |
| Reactions where the shot was given | 13.9% | 10.5% |
| Headache | 13.6% | 12.6% |
| Low blood sugar (only people with type 2 diabetes were counted) | 12.6% | 6.6% |
| Indigestion (dyspepsia) | 9.6% | 2.7% |
| Tiredness (fatigue) | 7.5% | 4.6% |
| Dizziness | 6.9% | 5.0% |
| Belly pain | 5.4% | 3.1% |
| High lipase, a pancreas enzyme, in blood tests | 5.3% | 2.2% |
| Upper belly pain | 5.1% | 2.7% |
Source for Saxenda trials in adults with obesity or overweight: Saxenda prescribing information on DailyMed , label revised .
Zepbound label
Zepbound trials in adults with obesity or overweight Up to 72 weeks
Adults with obesity or overweight in 2 trials. One trial included only people with type 2 diabetes; the other left them out. 2,519 got Zepbound in three dose groups and 958 got placebo.
| Reported problem | Zepbound groups | Placebo |
|---|---|---|
| Nausea | 25% to 29% | 8% |
| Diarrhea | 19% to 23% | 8% |
| Constipation | 11% to 17% | 5% |
| Vomiting | 8% to 13% | 2% |
| Belly pain | 9% to 10% | 5% |
| Indigestion (dyspepsia) | 9% to 10% | 4% |
| Shot-site reactions, like redness, itching, or bruising | 6% to 8% | 2% |
| Tiredness or weakness (fatigue) | 5% to 7% | 3% |
| Allergic reactions, mostly rash or itching | 5% | 3% |
| Burping | 4% to 5% | 1% |
| Hair loss | 4% to 5% | 1% |
| Acid reflux (GERD) | 4% to 5% | 2% |
Source for Zepbound trials in adults with obesity or overweight: Zepbound prescribing information on DailyMed , label revised .
What these numbers do not show
- The labels say side-effect rates from one medicine's trials cannot be directly compared with rates from another medicine's trials.
- Each label lists more warnings than these tables show, such as pancreatitis and gallbladder problems. The full tables, notes, and warnings are linked below.
- Neither label recommends using the medicine with other products made with the same ingredient or with any GLP-1 medicine.
- There are rare reports of people on GLP-1 medicines breathing stomach contents into the lungs during surgery or deep sedation. Both labels say to tell the care team before any planned surgery or procedure.
- The Zepbound label says it may make birth control pills work less well, mostly in the first weeks and after a dose increase. It advises switching to a non-pill method or adding a barrier method, such as condoms, for 4 weeks after starting and for 4 weeks after each dose increase.
- Each label covers its own uses. Ask the prescriber before changing, stopping, or combining any of these medicines or diabetes medicines.
- Trials can miss rare harms and harms that take years to appear.
- These numbers describe Saxenda and Zepbound. They do not describe compounded tirzepatide or liraglutide, or products sold online as research peptides.
Full tables, notes, and warnings
Report a side effect
You can report a suspected side effect to the FDA at 1-800-FDA-1088 or through FDA MedWatch . If a reaction feels serious, get medical care first.
Other label comparisons
- Zepbound vs Wegovy: side effects in the weight-management labels
- Mounjaro vs Ozempic: side effects in the type 2 diabetes labels
- Mounjaro vs Zepbound: the same medicine in the diabetes and weight labels
- Ozempic vs Wegovy: the same medicine in the diabetes and weight labels
- Victoza vs Ozempic: side effects in the type 2 diabetes labels
- Saxenda vs Wegovy: side effects in the weight-management labels
- Forteo vs Tymlos: side effects in the osteoporosis labels