Semaglutide: GLP-1 receptor agonist
A GLP-1 receptor agonist and the most-studied modern weight-loss and diabetes drug — FDA-approved by prescription, though the 'research peptide' versions sold online are not the approved product.
What is Semaglutide?
Semaglutide is a GLP-1 receptor agonist. In branded, FDA-approved forms it is prescribed for type 2 diabetes (Ozempic) and chronic weight management (Wegovy), and it has the strongest clinical evidence in its drug class. Note that the semaglutide sold by peptide vendors as a 'research' compound is not the FDA-approved product and is not quality-assured; approved semaglutide is a prescription medicine used under medical supervision.
Published-literature summary: GLP-1 receptor agonist with the most robust clinical evidence in the class. STEP 1 trial (NEJM, 2021) demonstrated ~15% mean body weight reduction over 68 weeks. SUSTAIN-6 showed significant cardiovascular risk reduction in T2D patients. Widely studied for obesity, T2D management, and metabolic syndrome. (Wilding et al. (2021) STEP 1 — N Engl J Med; Marso et al. (2016) SUSTAIN-6 — N Engl J Med)
How Semaglutide works (mechanism)
Semaglutide mimics the gut hormone GLP-1. It enhances glucose-dependent insulin secretion, slows gastric emptying, and acts on appetite centres in the brain to reduce food intake — which together drive weight loss and improved blood-sugar control. In the STEP 1 obesity trial, once-weekly semaglutide produced a mean weight reduction of about 14.9% over 68 weeks versus 2.4% for placebo [1].
Why it's studied / reported uses
Chronic weight management
The STEP programme established substantial, sustained weight loss with once-weekly semaglutide plus lifestyle support in adults with overweight/obesity [1][2]. This is an FDA-approved indication (Wegovy).
Type 2 diabetes & cardiovascular risk
As Ozempic, semaglutide is approved for glycemic control in type 2 diabetes, and trials in that population have shown cardiovascular-risk reduction. These are prescription uses under medical supervision.
Dosing reported in studies
Route: subcutaneous
Slow titration is used specifically to reduce nausea/GI effects.
Route: subcutaneous
Maintenance dose in the STEP-1 obesity trial.
Sources: Wilding et al. (2021) STEP 1 — N Engl J Med · Marso et al. (2016) SUSTAIN-6 — N Engl J Med
A GLP-1 agonist. FDA-approved forms exist under prescription; the peptide itself is prescription-only. These figures reflect what studies or protocols reported — not a recommendation and not tailored to you.
Calculate a dose in the reconstitution calculator →Common combinations & stacks
Combinations
In investigational work semaglutide has been combined with the amylin analog cagrilintide (the 'CagriSema' combination). This is trial-stage; semaglutide itself should only be used as prescribed.
Safety & side effects
Gastrointestinal effects — nausea, vomiting, diarrhoea, constipation — are the most common and are dose-related, which is why approved dosing titrates up slowly. Approved labels carry a boxed warning regarding thyroid C-cell tumours seen in rodents (contraindicated with a personal/family history of medullary thyroid carcinoma or MEN 2), and note risks including pancreatitis and gallbladder disease. Semaglutide is prescription-only for good reason and should be used under a clinician's care.
Studies & references
- Once-weekly semaglutide in adults with overweight or obesity (STEP 1) — PubMed 33567185 (Wilding et al., NEJM 2021)
- STEP 1 trial registration — semaglutide for overweight/obesity — ClinicalTrials.gov NCT03548987
Frequently asked questions
Is semaglutide FDA-approved?
Yes — in branded prescription forms (Wegovy for weight management, Ozempic/Rybelsus for type 2 diabetes). The unbranded 'research' semaglutide sold by peptide vendors is not the approved product.
How is semaglutide dosed?
Approved use titrates slowly — for weight management, roughly 0.25 → 0.5 → 1.0 → 1.7 → 2.4 mg once weekly, stepping up about every 4 weeks (see the dosing section). Titration limits nausea. This is not a recommendation; dosing should be set by a prescriber.
What are the side effects?
Mostly gastrointestinal (nausea, vomiting, diarrhoea), usually dose-related and easing over time. Serious risks and contraindications are on the approved label — discuss with a doctor.
How much weight loss does semaglutide cause?
In the STEP 1 trial, mean weight loss was about 14.9% at 68 weeks versus 2.4% on placebo. Individual results vary.
⚠ Research & educational use only. This page is compiled from published research and does not constitute medical advice. Semaglutide is FDA-approved as a prescription medicine in branded forms (e.g. Wegovy for weight management, Ozempic for type 2 diabetes). Nothing here is a recommendation to use or a prescription. Safe use can only be determined by a licensed physician. Last updated 2026-07-06.