Also known as: Ozempic, Wegovy, Rybelsus, GLP-1 receptor agonist
An FDA-approved GLP-1 receptor agonist with large randomised trials for type 2 diabetes, chronic weight management and cardiovascular risk reduction — the strongest evidence base of any peptide in this publication.
Multiple large, long randomised placebo-controlled trials (SUSTAIN, PIONEER, STEP, SELECT programmes) with tens of thousands of participants show glycaemic improvement, ~15% mean weight loss at 2.4 mg, and reduced major adverse cardiovascular events in high-risk adults.
Regulatory status (US)
FDA-approved for this use
FDA-approved for type 2 diabetes (Ozempic 2017, Rybelsus 2019), chronic weight management (Wegovy 2021) and reduction of major cardiovascular events in adults with CVD and overweight/obesity (Wegovy 2024). The FDA declared the semaglutide shortage resolved in February 2025, ending most compounding.
Mechanism (proposed)
Activates GLP-1 receptors to enhance glucose-dependent insulin secretion, suppress glucagon, slow gastric emptying and reduce appetite through central pathways.
Semaglutide and tirzepatide are the best-evidenced peptides in medicine — for specific uses. We separate the approved indications with large trials from the emerging research (kidney, liver, heart failure, sleep apnoea, Alzheimer's) and the open questions about regain, muscle loss and compounded products.
Semaglutide is an engineered version of the gut hormone GLP-1, modified so that a single injection acts for about a week. It is the best-studied peptide in this publication by a wide margin, with tens of thousands of trial participants across diabetes, weight management and cardiovascular outcomes.
For chronic weight management the pivotal STEP 1 trial showed roughly 15% mean weight loss over 68 weeks[1]; for cardiovascular risk, SELECT showed a 20% relative reduction in major adverse cardiovascular events in high-risk adults without diabetes[2]. Both uses are FDA-approved[4]. The same programme also documented substantial weight regain after stopping[3] — a finding that matters as much as the headline loss.
Emerging uses are covered in the full analysis: kidney outcomes in type 2 diabetes (FLOW, positive), liver disease (ESSENCE, positive), and Alzheimer's disease (evoke/evoke+, negative in November 2025).
FDA-approved for three indications under three brand names. The compounding window that opened during the shortage closed when the FDA declared the shortage resolved in February 2025; the agency has since warned about adverse events linked to compounded and counterfeit semaglutide.
Safety summary
Common gastrointestinal effects (nausea, vomiting, diarrhoea, constipation) lead to discontinuation in a minority; boxed warning for thyroid C-cell tumours based on rodent studies; pancreatitis, gallbladder disease, ileus, hypoglycaemia with insulin/sulfonylureas, and possible increase in diabetic retinopathy complications are labelled. Substantial weight regain follows discontinuation. Compounded and counterfeit products carry additional risks.
Frequently asked questions
Is semaglutide a peptide?
Yes. It is a modified 31-amino-acid analogue of the human hormone GLP-1, engineered for a roughly one-week half-life.
How much weight do people lose on semaglutide?
In the STEP 1 trial, mean weight loss was about 15% at 68 weeks versus 2.4% on placebo. Individual results vary widely, and much of the weight returns after stopping.
Is compounded semaglutide the same thing?
No. Compounded products are not FDA-approved, are not reviewed for safety or effectiveness, and were legally compounded only while the shortage lasted; the FDA declared it resolved in February 2025 and has warned about adverse events and counterfeit products.
References
Numbered in order of first use. Study type is shown for every source; see our methodology for how we rank evidence.
Review status: Editorially reviewed against primary sources. This article was fact-checked against the primary sources listed in the references by our editorial team, and it has not been reviewed by a licensed clinician. It is educational content, not medical advice. Read our editorial policy and methodology. Spotted an error? Tell us.
Profile by Tristen Ta. Published August 15, 2026; updated August 15, 2026.
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