GLP-1 receptor agonist for blood sugar regulation and weight management. Sold as Ozempic®, Wegovy®, and Rybelsus®.
Last Updated: May 2026
Semaglutide is a 31-amino-acid synthetic GLP-1 receptor agonist developed by Novo Nordisk, marketed as Ozempic for type 2 diabetes, Wegovy for chronic weight management, and Rybelsus as the only oral GLP-1 receptor agonist. It received initial FDA approval in 2017 (Ozempic) and 2021 (Wegovy). Research-grade semaglutide is sold by third-party laboratories for laboratory use only — that material is not the FDA-approved prescription product and carries no pharmacy-grade quality controls.
Semaglutide activates the GLP-1 receptor to increase glucose-dependent insulin secretion, slow gastric emptying, suppress appetite via central pathways, and reduce hepatic glucose production. The molecule is modified from native GLP-1 with two amino acid substitutions and a C18 fatty diacid side chain that binds serum albumin, extending half-life to approximately 7 days and enabling once-weekly subcutaneous dosing. Rybelsus uses an oral absorption enhancer (SNAC) to achieve bioavailability through the gastric mucosa. Evidence level: Human RCT (multiple Phase 3 trials in STEP, SUSTAIN, and PIONEER programs).
In STEP 1 (n=1,961), semaglutide produced an average weight loss of 14.9% at the 2.4 mg dose over 68 weeks in adults with obesity without type 2 diabetes, versus 2.4% for placebo. In type 2 diabetes (SUSTAIN program), semaglutide reduced HbA1c by up to 1.8 percentage points and demonstrated cardiovascular outcome benefit in SUSTAIN-6. The SELECT trial later established cardiovascular event reduction in obesity without diabetes — a first-in-class result. Evidence level: Human RCT (Phase 3, multiple programs).
Semaglutide is the founding compound of the modern GLP-1 weight-loss class, but produces lower percent weight loss than the dual and triple agonists that followed it. Tirzepatide's SURMOUNT-1 result (22.5% at 72 weeks) exceeded semaglutide's STEP 1 result (14.9% at 68 weeks) in matched populations, and SURPASS-2 demonstrated tirzepatide superiority head-to-head in type 2 diabetes. Retatrutide's Phase 3 readouts are exceeding both. Full cross-compound comparison is in our comparing semaglutide and tirzepatide guide.
| Compound | Mechanism | Phase 3 weight loss | Regulatory status |
|---|---|---|---|
| Retatrutide | GLP-1 + GIP + glucagon (triple) | 28.7% — TRIUMPH-4, 68 wks | Investigational |
| Tirzepatide | GLP-1 + GIP (dual) | 22.5% — SURMOUNT-1, 72 wks | FDA-approved (Mounjaro/Zepbound) |
| Semaglutide | GLP-1 (single) | 14.9% — STEP 1, 68 wks | FDA-approved (Ozempic/Wegovy) |
The most common semaglutide side effects in STEP 1 were gastrointestinal — nausea (44%), diarrhea (32%), vomiting (25%), and constipation (24%) — typically mild-to-moderate and concentrated in the dose-escalation phase. Less common but clinically relevant signals include rare pancreatitis cases, gallbladder events, and reported "Ozempic face" / "Ozempic butt" cosmetic changes attributable to rapid fat loss. Discontinuation rates due to adverse events were 7.0% on semaglutide versus 3.1% on placebo. Evidence level: Human RCT (Phase 3). Cross-compound side effect comparison is in peptide side effects by compound and route.
Semaglutide is FDA-approved as Ozempic (type 2 diabetes, 2017), Rybelsus (oral, 2019), and Wegovy (chronic weight management, 2021), with EMA approval following for all three. It is available by prescription through licensed pharmacies. Research-grade semaglutide sold by third-party laboratories is not the FDA-approved prescription product. For prescription access pathways including telehealth options, see can you get semaglutide without a prescription.
Because FDA approval applies to Novo Nordisk's pharmacy-distributed Ozempic, Wegovy, and Rybelsus — not to research-grade semaglutide sold by third-party labs. Research-grade semaglutide is a separate supply chain with its own quality risks: wider purity variance, occasional underdosing, and inconsistent endotoxin control. Independent HPLC purity testing and mass spectrometry identity confirmation (expected MW 4,113.6 Da) are the only meaningful purity signals a research-grade vendor can provide. Learn how to interpret these in our how-to-test-peptides hub.
Peptigrity purchases semaglutide vials anonymously at standard customer pricing, sends them to ISO-accredited third-party labs for HPLC and mass spectrometry analysis, and publishes the unedited certificate of analysis. The lab test table above this section shows the full cross-shop dataset, sortable by date, purity, and labeled-vs-tested quantity. Tests come from named labs including Freedom Diagnostics, Janoshik Analytical, Chromate, and Vanguard Laboratory. Methodology detail is in how we calculate trust scores.
The only reliable purity signal is an independent third-party HPLC certificate of analysis from a lab the vendor does not own or pay. Peptigrity publishes independent semaglutide test results from ISO-accredited labs in the table above. For COA interpretation, see red flags in peptide certificates of analysis and the compound-specific where to buy semaglutide guide.
Research-grade semaglutide is legally sold as a research chemical without prescription in most jurisdictions, but is not approved for human consumption. The FDA-approved versions (Ozempic, Wegovy, Rybelsus) require a prescription, which can be obtained through traditional medical care or telehealth platforms. Full pathway breakdown is in can you get semaglutide without a prescription.
Compounding pharmacy access to semaglutide depends on FDA shortage status and 503A/503B regulations, both of which have shifted during 2024–2025. When semaglutide is on the FDA shortage list, 503A pharmacies may compound it; when off the list, that pathway closes. Track current status in FDA peptide regulation 2025–2026: the complete timeline.
Research-grade semaglutide is manufactured without the pharmaceutical-grade overhead (FDA inspections, full GMP compliance, branded packaging, distribution markups) that prices the prescription products. It also carries no regulatory protection or quality guarantee. Current research-grade pricing is broken down in how much do peptides cost.
No. Peptigrity is an independent review platform, not a medical authority. The doses studied in STEP and SUSTAIN (0.25 mg through 2.4 mg weekly, with mandatory titration) were administered under clinical supervision. Anyone considering semaglutide should consult a licensed physician about the prescription product.
Tirzepatide produces larger percent weight loss than semaglutide in matched Phase 3 trials and beat semaglutide head-to-head in type 2 diabetes (SURPASS-2). SURMOUNT-1 reported 22.5% at 72 weeks for tirzepatide versus STEP 1's 14.9% at 68 weeks for semaglutide. Full comparison in our comparing semaglutide and tirzepatide guide.
This section is for educational and informational purposes only and does not constitute medical advice. Research-grade semaglutide sold for laboratory use is not the FDA-approved prescription product (Ozempic, Wegovy, Rybelsus). Always consult a qualified healthcare provider before using any peptide or research compound. Peptigrity is an independent review platform and does not sell, endorse, or recommend specific products or vendors.
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