Weight Loss Injections: What Is FDA-Approved and How Well They Work

Last updated October 27, 2026

Short answer: Three FDA-approved injections are prescribed for weight management: Wegovy (semaglutide, weekly), Zepbound (tirzepatide, weekly) and Saxenda (liraglutide, daily). In the trials behind their labels, average weight loss was 14.9% on Wegovy at 68 weeks, up to 20.9% on Zepbound at 72 weeks, and 7.4% on Saxenda at 56 weeks. All are prescription medicines, and the FDA warns against unapproved or compounded versions.

The FDA-approved weight loss injections

These come from the clinical studies sections of each label, in adults with obesity or overweight plus a weight-related condition, and without type 2 diabetes for the figures shown. Everyone in the trials, including the placebo groups, also received diet and activity counseling, and the labels describe each medication as used together with a reduced-calorie diet and increased physical activity. These are three separate trials, so the table is not a head-to-head comparison. For the one direct comparison of two of them, see semaglutide vs. tirzepatide.

How many people lose a meaningful amount?

On Saxenda, 62.3% of people lost at least 5% of their body weight (34.4% on placebo) and 33.9% lost more than 10% (15.4% on placebo). For the same breakdown on Wegovy and Zepbound, see do GLP-1s work?

What about Ozempic and Mounjaro?

Ozempic and Mounjaro contain the same active drugs as Wegovy and Zepbound, but they are approved for type 2 diabetes. Using them for weight loss is an off-label decision between a patient and prescriber. See Ozempic for weight loss and Mounjaro vs. Zepbound.

Compounded and unapproved injections

The FDA says unapproved versions do not go through its review for safety, effectiveness and quality, and that compounded drugs are not FDA approved. As of May 31, 2026 it had received 990 reports of adverse events linked to compounded semaglutide and more than 730 linked to compounded tirzepatide, and it notes these are likely underreported. Some of the reports, involving dosing errors with compounded injectable semaglutide, required hospitalization. The FDA also warns that counterfeit versions may contain the wrong ingredients.

• The FDA advises getting a prescription from your doctor and filling it at a state-licensed pharmacy.
• If you buy online, buy only from state-licensed pharmacies.
• The FDA says compounded drugs should be used only when medical needs cannot be met by an FDA-approved drug.

Before you start

• Check the label criteria for BMI and weight-related conditions in our BMI guide.
• Ask what the dose schedule looks like. See the semaglutide and tirzepatide dosage charts.
• Know the common side effects and what to do about a missed dose.
• Ask about cost and coverage up front, including what happens if you need to stop.

Related guides: BMI requirements, semaglutide dosage chart, tirzepatide dosage chart, missed dose and cost.