At a glance

What is semaglutide?

Semaglutide is a synthetic peptide known as a GLP-1 receptor agonist¹. It is a modified copy of human glucagon-like peptide-1 (GLP-1), a hormone the gut releases after eating that helps regulate blood sugar and appetite. Semaglutide shares about 94% of its structure with natural GLP-1, but it is altered so that it resists rapid breakdown and binds to proteins in the blood. That is why it can be dosed once a week rather than many times a day.

It is made by Novo Nordisk and sold under three brand names. Ozempic is a weekly injection for type 2 diabetes, Wegovy is a weekly injection for weight management (and now comes as a daily pill), and Rybelsus is a daily tablet for type 2 diabetes.

How does semaglutide work?

Semaglutide activates the GLP-1 receptor, copying the action of a natural hormone. Through that receptor, it:

• Prompts the pancreas to release insulin when blood sugar is high, and because that effect depends on elevated glucose, semaglutide on its own carries a low risk of causing low blood sugar
• Reduces the release of glucagon (a hormone that raises blood sugar)
• Slows the rate at which the stomach empties
• Acts on appetite centers in the brain to reduce hunger and food intake

Together, these effects lower blood sugar and reduce how much a person eats.

The trial results have been substantial:

Is it FDA-approved?

Yes, and its approved uses have expanded steadily since 2017.

• Ozempic: Approved in 2017 for type 2 diabetes, later to reduce cardiovascular risk in people with type 2 diabetes, and in January 2025 to reduce the risk of worsening kidney disease and cardiovascular death in adults with type 2 diabetes and chronic kidney disease. In January 2026 one Rybelsus tablet formulation was renamed Ozempic tablets.
• Rybelsus: Approved in 2019 as the first oral GLP-1 pill, for type 2 diabetes, and in October 2025 to reduce cardiovascular risk in adults with type 2 diabetes at high risk.
• Wegovy: Approved in June 2021 for chronic weight management, in March 2024 to reduce cardiovascular risk in adults with cardiovascular disease and overweight or obesity, and in August 2025 for noncirrhotic MASH⁵ (a form of fatty liver disease) with moderate to advanced liver fibrosis. A daily pill was approved in December 2025, and a higher 7.2 mg dose, Wegovy HD, received accelerated approval in March 2026.

What is semaglutide prescribed for?

Its uses fall into a few groups. For type 2 diabetes, Ozempic and Rybelsus are prescribed to improve blood sugar control alongside diet and exercise. For weight management, Wegovy is approved for adults with obesity (a BMI of 30 or higher) or with overweight (a BMI of 27 or higher) plus at least one weight-related condition such as high blood pressure or high cholesterol, and it is also approved for adolescents aged 12 and older with obesity.

Beyond blood sugar and weight, semaglutide is prescribed to lower the risk of heart attack, stroke, and cardiovascular death in specific populations, to slow kidney disease in people with type 2 diabetes and chronic kidney disease, and to treat noncirrhotic MASH with fibrosis.

It is not a treatment for type 1 diabetes. It should not be used by people with a personal or family history of medullary thyroid carcinoma, or by people with Multiple Endocrine Neoplasia syndrome type 2, or by anyone with a known allergy to semaglutide.

What are the side effects?

The most common side effects are gastrointestinal, and they are often strongest when the dose is first increased:

• Nausea
• Vomiting
• Diarrhea
• Constipation
• Abdominal pain
• Decreased appetite
• Indigestion or heartburn
• Fatigue
• Headache and dizziness
• Tingling or burning skin sensations, mainly at the highest Wegovy dose

Less common but more serious risks include:

• Thyroid C-cell tumors: semaglutide carries a boxed warning¹ based on rodent studies that found thyroid tumors. It is not known whether this happens in humans.
• Pancreatitis, or inflammation of the pancreas
• Gallbladder problems, including gallstones
• Acute kidney injury, usually caused by dehydration from vomiting or diarrhea
• Worsening of diabetic retinopathy in people with type 2 diabetes
• Low blood sugar, especially when combined with insulin or a sulfonylurea
• Delayed stomach emptying, which can raise the risk of aspiration during surgery or anesthesia
• Serious allergic reactions

Frequently asked questions

How does semaglutide work to reduce appetite and body weight?

Semaglutide activates GLP-1 receptors, including receptors in brain areas involved in appetite regulation⁷, which reduces hunger and food intake, and it slows gastric emptying. The drug is structurally modified from endogenous GLP-1 with a fatty acid side chain that binds it to albumin, which decreases renal clearance and protects it from degradation, giving it an elimination half-life of about one week. In the STEP 1 trial (N=1,961), semaglutide produced 14.9% mean weight loss⁸ compared to 2.4% with placebo at 68 weeks.

What did the SELECT trial find about semaglutide and heart health?

The SELECT trial demonstrated that semaglutide 2.4 mg weekly reduced major adverse cardiovascular events by 20% in adults with overweight or obesity and established cardiovascular disease, without diabetes. The study enrolled 17,604 adults aged 45 and older with BMI ≥27 and preexisting cardiovascular disease, following them for a mean of 39.8 months, and found a hazard ratio of 0.80⁹ (95% CI 0.72-0.90). A sub-analysis of 4,286 patients with heart failure showed MACE reduction in both¹⁰ heart failure with reduced ejection fraction (HR 0.65) and heart failure with preserved ejection fraction (HR 0.69). An estimated 33% of the cardiovascular benefit¹¹ was mediated through waist circumference reduction.

What happens to weight when you stop taking semaglutide?

Weight regain after semaglutide discontinuation is well-documented, participants who stop therapy typically regain a substantial portion of lost weight within a year. In a STEP 1 extension, participants regained about two-thirds of their prior weight loss¹² one year after stopping. In the STEP 4 trial, after a 20-week run-in on semaglutide 2.4 mg, those who continued semaglutide lost an additional 7.9%¹³, while those switched to placebo regained 6.9% from week 20 to 68. This finding indicates the ongoing nature of therapy, though individual trajectories vary.

Is semaglutide FDA-approved, and what are the different brand names?

Semaglutide has three FDA-approved branded formulations targeting distinct indications. Ozempic is a subcutaneous injection FDA-approved in December 2017 for type 2 diabetes and later for cardiovascular risk reduction. Wegovy is a subcutaneous injection approved in 2021 for chronic weight management and in 2024 for MACE reduction in adults with overweight/obesity and ASCVD. Rybelsus is an oral tablet approved in 2019 for type 2 diabetes.

How does semaglutide compare to liraglutide for weight loss?

In head-to-head comparison, semaglutide produced significantly greater weight loss than liraglutide. In the STEP 8 trial (N=338; 68 weeks), semaglutide produced 15.8% weight loss versus 6.4%¹⁴ with liraglutide, a difference of −9.4 percentage points. Both are GLP-1 receptor agonists, and semaglutide has an elimination half-life of about one week⁷.

How does semaglutide affect HbA1c in type 2 diabetes?

Semaglutide consistently reduces HbA1c in type 2 diabetes, with the magnitude of reduction depending on dose and formulation. In the SUSTAIN FORTE trial (N=961 adults with type 2 diabetes over 40 weeks), semaglutide 2.0 mg reduced HbA1c by 2.2 percentage points¹⁵ and body weight by 6.9 kg, while semaglutide 1.0 mg reduced HbA1c by 1.9 percentage points. A 2023 meta-analysis of 17 RCTs (N=14,940) found that subcutaneous semaglutide 1.0 mg reduced HbA1c by a mean of 1.36¹⁶ percentage points versus placebo (95% CI −1.59 to −1.13) with no increase in serious adverse events.

How does semaglutide differ from tirzepatide?

Semaglutide activates only GLP-1 receptors, while tirzepatide activates both GLP-1 and GIP receptors and has produced greater weight reduction in comparative data. In SURMOUNT-1 (N=2,539; 72 weeks), tirzepatide 15 mg achieved 20.9% weight loss¹⁷, compared to 14.9% with semaglutide 2.4 mg in the separate STEP 1 trial (N=1,961; 68 weeks). A 2024 network meta-analysis in adults with type 2 diabetes (28 RCTs, 23,622 participants) found that, compared with placebo, tirzepatide 15 mg reduced HbA1c by 1.96 percentage points¹⁸ versus 1.59 for semaglutide 2.0 mg, a difference the authors judged comparable, and reduced body weight by 9.57 kg versus 4.97 kg. Semaglutide's cardiovascular outcome evidence includes the SELECT trial (N=17,604) in people without diabetes.

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