GLP-1 weight loss injections are prescription medicines that mimic gut hormones to reduce appetite and slow digestion. In the US, the injections approved for weight management are Wegovy (semaglutide), Zepbound (tirzepatide) and Saxenda (liraglutide). They are used with a reduced-calorie diet and more physical activity, doses start low and rise in steps, and nausea and other digestive effects are the most common side effects. A prescriber decides who qualifies and which one to use.
Which injections are approved for what
Ozempic and Mounjaro contain the same active ingredients as Wegovy and Zepbound but are approved for type 2 diabetes, not weight management. This table sticks to what each label states.
| Brand | Active ingredient | Maker | Approved use (US) | Schedule |
|---|---|---|---|---|
| Wegovy | Semaglutide | Novo Nordisk | Weight reduction and long-term maintenance (obesity, or overweight with a weight-related condition); lower cardiovascular risk in adults with heart disease and obesity or overweight; MASH (fatty liver disease) with moderate to advanced fibrosis in adults | Weekly; 0.25 mg for 4 weeks, rising every 4 weeks to 2.4 mg maintenance |
| Zepbound | Tirzepatide | Eli Lilly | Weight reduction and long-term maintenance (obesity, or overweight with a weight-related condition); moderate to severe obstructive sleep apnea in adults with obesity | Weekly; 2.5 mg for 4 weeks, then 5 mg, rising in 2.5 mg steps after at least 4 weeks; maintenance 5, 10 or 15 mg |
| Saxenda | Liraglutide | Novo Nordisk | Weight reduction and long-term maintenance (adults, and ages 12+ weighing over 60 kg with obesity) | Daily; 0.6 mg for one week, rising weekly to 3 mg |
| Ozempic | Semaglutide | Novo Nordisk | Type 2 diabetes | Weekly; 0.25 mg, 0.5 mg, 1 mg, 2 mg |
| Mounjaro | Tirzepatide | Eli Lilly | Type 2 diabetes | Weekly; 2.5 mg, rising in 2.5 mg steps up to 15 mg |
Sources: Wegovy, Zepbound, Saxenda, Ozempic and Mounjaro prescribing information, sections 1 and 2. Wegovy also comes as a daily tablet; see Wegovy pill. Foundayo (orforglipron), approved in April 2026, is another daily GLP-1 tablet for weight management (Foundayo prescribing information). The Wegovy label allows up to 7.2 mg weekly in adults who tolerate 2.4 mg and need more weight reduction. Each label says not to combine its medicine with other GLP-1 medicines.
How the injections work
GLP-1 is a hormone involved in blood sugar and appetite, and these drugs activate its receptor. Tirzepatide also activates the receptor for a second hormone, GIP (Mounjaro label, section 12.1). Together with a reduced-calorie diet, the effect is lower food intake. Because the drugs slow stomach emptying, they can change how other oral medicines are absorbed, which your prescriber should know about.
What results look like
Trial results from the labels, each with a lifestyle program:
- Wegovy 2.4 mg: average weight change of -14.9% at 68 weeks versus -2.4% with placebo (Wegovy label, Table 8).
- Zepbound: at 72 weeks, -3.1% with placebo versus -15.0%, -19.5% and -20.9% with 5, 10 and 15 mg (Zepbound label, section 14).
These are averages; individual results vary. Read more about semaglutide and tirzepatide.
Who is it for
The labels cover adults with obesity, or with overweight plus at least one weight-related condition, and in some cases adolescents. They are not a shortcut for everyone. People with a personal or family history of medullary thyroid carcinoma or MEN 2 must not use them. Your prescriber reviews your health history, other medicines and goals.
Starting and maintaining treatment
Every label starts low and raises the dose in steps, which reduces digestive side effects. Wegovy’s label says to consider delaying a dose increase by 4 weeks if a dose isn’t tolerated. Missed-dose rules differ by drug: Zepbound allows a missed dose within 4 days; for Wegovy, take it if the next dose is more than 2 days away; for Saxenda and others, follow your label. After 2 or more missed Wegovy doses in a row, the label says to restart escalation at a lower dose. Do not adjust doses on your own.
Lifestyle, tracking and check-ins
These medicines are approved as an addition to diet and activity, not a replacement. A simple routine helps: log injection day, dose and site; meals and protein; water; side effects and when they started; weight at the same time each week. Mingo is a GLP-1 tracker for iPhone and Android that logs shots and doses, food and protein, side effects and weight in one place. It doesn’t replace your doctor. Get the app. For a wider plan, see our GLP-1 weight loss medication guide.
Side effects and safety
Labels list nausea, diarrhea, vomiting and constipation among the most common reactions; Saxenda’s also include injection site reactions, headache and low blood sugar. All carry a boxed warning about thyroid C-cell tumors seen in rodents. Other warnings include pancreatitis, gallbladder disease, kidney injury after dehydration, and aspiration risk during anesthesia. Tell your prescriber about new or severe abdominal pain, repeated vomiting, vision changes or any symptom that worries you, and read GLP-1 side effects: what to expect and how to manage them. This is general information, not medical advice.
Stopping, long-term use and cost
A systematic review reports that, after semaglutide 2.4 mg was stopped, about two-thirds of the weight lost was regained, and concludes that obesity needs long-term management (PMC review). Decide with your prescriber before stopping.
On cost, US spending on GLP-1 medicines grew from $13.7 billion in 2018 to $71.7 billion in 2023, with semaglutide and tirzepatide making up 70% of it (economic evaluation, PMC). Coverage and price vary by country and insurer; ask your prescriber, pharmacist or insurer. Use only products prescribed for you and dispensed by a licensed pharmacy.
Key takeaways
- The injections approved for weight management are Wegovy, Zepbound and Saxenda; Ozempic and Mounjaro are approved for type 2 diabetes.
- Doses start low and rise in steps; never change them on your own.
- Digestive side effects are the most common; the labels carry a boxed thyroid tumor warning.
- Weight tends to return after stopping, so ask about the long-term plan.
Frequently asked questions
What is a GLP-1 weight loss injection?
A prescription injection that activates the GLP-1 receptor (tirzepatide also activates GIP), used with diet and activity to reduce excess body weight. Wegovy, Zepbound and Saxenda are the approved options in the US.
How does the injection help with weight loss?
It lowers appetite and slows stomach emptying, so people tend to eat less. Results vary from person to person.
Are there side effects to these injections?
Yes. Nausea, vomiting, diarrhea and constipation are most common, and rarer serious problems such as pancreatitis and gallbladder disease are in the warnings. Tell your prescriber about severe or lasting symptoms.
How much do weight loss injections cost?
It depends on the drug, country, insurance and pharmacy. Ask your prescriber or insurer for current details.
Is a prescription needed for weight loss injections?
Yes. These are prescription medicines; buy them only with a prescription from a licensed pharmacy.
