Wegovy (semaglutide): What It Is, Trial History and Regulatory Status

Wegovy is a brand name for semaglutide, a glucagon-like peptide-1 (GLP-1) receptor agonist marketed by Novo Nordisk and administered as a once-weekly subcutaneous injection. It is a prescription medicine approved in the United States for chronic weight management and, in later label expansions, for additional cardiometabolic indications. This page summarises what the published literature and the product label state about semaglutide as used in Wegovy: its mechanism, the pivotal trial programme, the adverse events reported in trials and reviews, and its regulatory history. This page is for educational purposes only and is not medical advice; consult a licensed physician or your prescriber about any medication.

Evidence tier: Established (FDA-approved; multiple randomized controlled trials).

What Wegovy Is

Active ingredient and drug class

The active ingredient in Wegovy is semaglutide, an analogue of the human incretin hormone GLP-1. A historical review of the discovery and development of liraglutide and semaglutide described semaglutide as a GLP-1 analogue engineered with amino-acid substitutions and a fatty-acid side chain that promotes binding to albumin and resistance to enzymatic degradation, changes that were introduced specifically to extend its duration of action (PMID 31031702). A 2024 systematic review of the clinical pharmacokinetics of semaglutide reported an elimination half-life of approximately one week, which is the property that supports once-weekly administration of the subcutaneous formulations (PMID 38952487).

Because semaglutide is a modified peptide molecule, Wegovy is sometimes described informally as a "peptide drug." In practice it is a regulated, FDA-approved prescription medicine dispensed through pharmacies under the supervision of a prescriber, and it is manufactured by Novo Nordisk.

How researchers describe its mechanism

GLP-1 receptor agonists act on receptors in the pancreas, gastrointestinal tract and central nervous system. A review of semaglutide for the treatment of obesity described glucose-dependent stimulation of insulin secretion, suppression of glucagon, delayed gastric emptying and central effects on appetite and energy intake as the mechanisms through which semaglutide produces weight reduction (PMID 34942372). Consistent with that mechanistic account, a two-year analysis from the STEP 5 trial reported improvements in patient-rated control of eating, including craving and hunger domains, in adults with overweight or obesity treated with semaglutide 2.4 mg once weekly compared with placebo (PMID 36655300).

Mechanistic work has continued beyond appetite pathways. A 2026 preclinical study in Cell Metabolism reported that some hepatoprotective effects of semaglutide occurred independently of weight loss and were mediated by GLP-1 receptors on intrahepatic sinusoidal endothelial cells (PMID 41985454). That work was laboratory research and does not describe outcomes in people taking Wegovy.

Approved Indications and Approval Timeline

The Wegovy label defines its indications, the populations they apply to, and the conditions of use. The table below summarises the sequence of United States approvals as stated by the regulator and label.

The label describes a stepwise dose-escalation schedule over several weeks intended to reduce gastrointestinal effects, culminating in the maintenance dose of semaglutide 2.4 mg once weekly that was studied in the pivotal obesity trials (PMID 36655300). These figures are presented here as label and trial facts, not as guidance; how and whether any regimen applies to an individual is a decision for that person and their prescriber.

Trial History: The Pivotal Studies as Published

The STEP programme in obesity

Semaglutide at the 2.4 mg weekly dose was evaluated in the Semaglutide Treatment Effect in People with obesity (STEP) programme of randomized, placebo-controlled phase 3 trials. A review of semaglutide for obesity summarised that programme and reported that semaglutide produced substantially greater weight reduction than placebo across the trials, alongside improvements in cardiometabolic risk markers such as waist circumference, blood pressure and lipids (PMID 34942372).

A 2022 systematic review and meta-analysis pooled randomized controlled trials of semaglutide for weight loss in obesity without diabetes and reported significantly greater reductions in body weight with semaglutide than with placebo, while also reporting a higher frequency of gastrointestinal adverse events in the semaglutide groups (PMID 36578889).

STEP 5: two-year data

STEP 5 extended follow-up to 104 weeks. In the published two-year analysis, researchers reported that adults with overweight or obesity randomized to semaglutide 2.4 mg once weekly had improved control-of-eating scores relative to placebo, including lower craving and hunger ratings, and that these changes accompanied the weight reductions observed in the trial (PMID 36655300).

SELECT: long-term weight outcomes in a cardiovascular trial

The SELECT trial randomized adults with overweight or obesity and established cardiovascular disease, but without type 2 diabetes, to semaglutide or placebo. A 2024 Nature Medicine analysis of the trial's weight outcomes reported that weight loss with semaglutide continued for roughly the first 65 weeks and was then sustained, with a mean reduction of about 10% of body weight and a reduction in waist circumference maintained through 208 weeks of follow-up (PMID 38740993). That analysis also reported that weight reduction occurred across subgroups defined by baseline characteristics (PMID 38740993). SELECT is the trial that supported the cardiovascular risk-reduction indication added to the label.

Observational and real-world reports

Beyond randomized trials, the SHAPE study examined electronic health-record data and reported weight reductions among patients with overweight or obesity and without type 2 diabetes who were treated with either semaglutide or tirzepatide in routine clinical practice, with the study noting that real-world adherence and dose escalation patterns differed from those in controlled trials (PMID 40875186). A 2023 JAMA medical news article summarised clinician commentary on the rapid uptake of semaglutide for weight loss, including discussion of weight regain after treatment discontinuation and questions about long-term use (PMID 37099334).

Adverse Events: What Studies Report

Gastrointestinal effects

Gastrointestinal symptoms were the most frequently reported adverse events across the semaglutide literature. A comprehensive safety review reported nausea, vomiting, diarrhoea and constipation as the dominant adverse events, usually mild to moderate in intensity and most common during dose escalation (PMID 34305810). The 2022 meta-analysis in obesity without diabetes similarly reported that gastrointestinal adverse events occurred more often with semaglutide than placebo and contributed to treatment discontinuation in some participants (PMID 36578889).

Pancreatic, gallbladder and other reported events

The same safety review discussed reported events involving the pancreas and gallbladder, including pancreatitis and cholelithiasis, and reviewed the available randomized and observational evidence on these signals alongside injection-site reactions and increases in heart rate (PMID 34305810). The obesity review also summarised tolerability findings and discontinuation rates from the phase 3 programme (PMID 34942372).

Diabetic retinopathy

Labels for semaglutide products carry a warning that rapid improvement in glucose control has been associated with temporary worsening of diabetic retinopathy. A 2022 meta-analysis of randomized controlled trials specifically evaluated diabetic retinopathy risk with semaglutide in patients with type 2 diabetes mellitus and examined pooled event rates across those trials (PMID 34894326). Readers with diabetes or existing eye disease would need to discuss retinal monitoring with their own clinicians.

Drug interactions reported in the literature

Because semaglutide slows gastric emptying, the absorption of co-administered oral medicines has been a subject of study; the pharmacokinetic systematic review discussed absorption and exposure characteristics relevant to that question (PMID 38952487). A 2025 case series and literature review reported lithium toxicity and altered lithium clearance in patients with bipolar disorder after semaglutide was initiated, and the authors recommended attention to monitoring in that population (PMID 40999647).

Boxed warning and contraindications on the label

The Wegovy label carries a boxed warning regarding the risk of thyroid C-cell tumours, based on findings in rodent studies; the label states that the human relevance of these findings has not been determined and contraindicates use in people with a personal or family history of medullary thyroid carcinoma or with multiple endocrine neoplasia syndrome type 2. The label also contraindicates use in people with a history of serious hypersensitivity to semaglutide and advises against use during pregnancy. Thyroid, pancreatic and other theoretical safety concerns have been reviewed in the published safety literature (PMID 34305810).

Regulatory Status

Wegovy was approved by the US Food and Drug Administration in June 2021 for chronic weight management in adults, with the adolescent indication added in 2022, the cardiovascular risk-reduction indication added in 2024 on the basis of the SELECT trial, and an accelerated approval for noncirrhotic MASH with moderate to advanced fibrosis granted in 2025. The European Medicines Agency authorised Wegovy for weight management in 2022, and the product is authorised in numerous other jurisdictions under the same brand. Wegovy is a prescription-only medicine everywhere it is approved.

Shortage listing and compounding

Rapid demand led the FDA to list semaglutide injection products, including Wegovy, on its drug shortage database beginning in 2022. While a drug is in shortage, federal law permits state-licensed (503A) and outsourcing (503B) facilities to compound copies of that drug under specified conditions. The FDA declared the semaglutide injection shortage resolved in February 2025 and set out transition periods after which compounding of essentially copies of the approved products would no longer fall within those exemptions. The agency has also stated publicly that compounded semaglutide products are not FDA-approved and have not been reviewed for safety, effectiveness or quality, and it has warned about dosing errors and unapproved salt forms of the active ingredient. These are regulatory facts rather than clinical recommendations, and nothing here is legal advice.

How Wegovy Differs From Other Semaglutide Products

Semaglutide is the active ingredient in more than one Novo Nordisk product, and the products differ by route, formulation strength range and approved indication rather than by molecule. The pharmacokinetic literature has characterised both subcutaneous and oral semaglutide, noting that the oral formulation requires an absorption enhancer and has markedly lower bioavailability than the injectable route (PMID 38952487).

The 2023 JAMA news article discussed the confusion that arose when a diabetes-indicated semaglutide product became widely discussed as a weight-loss treatment, and the distinction between on-label and off-label use (PMID 37099334). Maximum approved doses and titration schedules differ between these products, which is why substituting one for another is a prescribing decision rather than an equivalence.

Consulting a Prescriber

Every element on this page — indication, eligibility criteria, dose escalation, monitoring and duration of treatment — is defined by a label and a clinical assessment, not by general information. Topics that clinicians commonly review include personal and family history of thyroid cancer, history of pancreatitis or gallbladder disease, diabetic eye disease and retinal monitoring, kidney function, pregnancy plans, mental-health history and concurrent medicines such as insulin, sulfonylureas or lithium, which was the subject of a 2025 case series reporting altered clearance after semaglutide initiation (PMID 40999647).

Key takeaways from the published record

• Semaglutide is an albumin-binding GLP-1 analogue engineered for extended action, with a half-life of about one week reported in pharmacokinetic reviews (PMID 38952487).
• Randomized trials and meta-analyses reported significantly greater weight loss with semaglutide than placebo in adults with obesity without diabetes (PMID 36578889).
• The SELECT analysis reported weight reduction of about 10% sustained through 208 weeks in adults with overweight or obesity and cardiovascular disease (PMID 38740993).
• Gastrointestinal adverse events were the most commonly reported effects in safety reviews, generally mild to moderate and concentrated during escalation (PMID 34305810).
• Regulatory status, boxed warning content and compounding rules are set by regulators and change over time; the current label is the authoritative source.

PeptideU is not affiliated with or endorsed by Novo Nordisk. Wegovy is a trademark of its owner. This page is for educational purposes only and is not medical advice; consult a licensed physician or your prescriber about any medication.

References

• The Discovery and Development of Liraglutide and Semaglutide (Frontiers in Endocrinology, 2019)
• Safety of Semaglutide (Frontiers in Endocrinology, 2021)
• Semaglutide and Diabetic Retinopathy Risk in Patients with Type 2 Diabetes Mellitus: A Meta-Analysis of Randomized Controlled Trials (Clinical Drug Investigation, 2022)
• Efficacy and Safety of Semaglutide for Weight Loss in Obesity Without Diabetes: A Systematic Review and Meta-Analysis (Journal of the ASEAN Federation of Endocrine Societies, 2022)
• Semaglutide for the treatment of obesity (Trends in Cardiovascular Medicine, 2023)
• Two-year effect of semaglutide 2.4 mg on control of eating in adults with overweight/obesity: STEP 5 (Obesity, 2023)
• As Ozempic's Popularity Soars, Here's What to Know About Semaglutide and Weight Loss (JAMA, 2023)
• Long-term weight loss effects of semaglutide in obesity without diabetes in the SELECT trial (Nature Medicine, 2024)
• Clinical Pharmacokinetics of Semaglutide: A Systematic Review (Drug Design, Development and Therapy, 2024)
• Real-World Weight Loss Observed With Semaglutide and Tirzepatide in Patients with Overweight or Obesity and Without Type 2 Diabetes (SHAPE) (Advances in Therapy, 2025)
• Lithium Toxicity and Altered Clearance Following Initiation of Semaglutide in Patients With Bipolar Disorder: A Case Series and Literature Review (Journal of Clinical Psychopharmacology, 2025)
• The weight-loss-independent hepatoprotective benefits of semaglutide are orchestrated by intrahepatic sinusoidal endothelial GLP-1 receptors (Cell Metabolism, 2026)