Semaglutide

Semaglutide is a long-acting GLP-1 receptor agonist modified with a C18 fatty diacid for albumin binding, enabling once-weekly subcutaneous (Ozempic, Wegovy) and once-daily oral (Rybelsus) administration. It is approved across three indications — glycemic control in type 2 diabetes, chronic weight management, and cardiovascular risk reduction — and in August 2025 received accelerated FDA approval for metabolic dysfunction-associated steatohepatitis (MASH). The cardiovascular outcomes program (SUSTAIN-6, SELECT, SOUL) demonstrates MACE reduction in patients with and without diabetes.

Semaglutide is a long-acting GLP-1 receptor agonist (GLP-1 RA). The Aib substitution at position 2 confers resistance to dipeptidyl peptidase-4 (DPP-IV) cleavage. The C18 fatty diacid chain binds non-covalently to serum albumin, extending the plasma half-life to approximately 1 week (168 h), enabling once-weekly SC dosing. Oral semaglutide (Rybelsus) uses the absorption enhancer sodium N-(8-[2-hydroxybenzoyl] amino) caprylate (SNAC) to facilitate gastric absorption. Semaglutide increases glucose-dependent insulin secretion, suppresses glucagon secretion, delays gastric emptying, and promotes satiety through central GLP-1 receptor activation in the hypothalamus (Drucker, 2018; Marso et al., NEJM 2016).

Approved labeled regimen

The label summary below is product-, indication-, and jurisdiction-specific; consult the full current label and a licensed clinician/pharmacist.

The entries summarize the cited US FDA labels for the named products and their approved indications.

• Ozempic: Initiate 0.25 mg SC qwk × 4 wk, then 0.5 mg qwk; may increase to 1.0 mg qwk after ≥4 wk at 0.5 mg; 2.0 mg qwk approved (label update Jan 2022).

• Wegovy: Initiate 0.25 mg SC qwk, titrate every 4 wk (0.5, 1.0, 1.7) to 2.4 mg qwk maintenance.

• Rybelsus: 3 mg daily × 30 days, then 7 mg daily; may increase to 14 mg daily. Must be taken on an empty stomach with ≤120 mL water, after ≥30 min wait.

Studied regimens (not recommendations)

• OASIS 4 evaluated oral semaglutide 25 mg daily for T2D; showed additional HbA1c reduction vs 14 mg.

• Doses up to 4.5 mg SC qwk have been evaluated in early-phase obesity studies.

What is not established

• Efficacy and safety in combination with tirzepatide or other incretin dual/triple agonists have not been studied.

• Long-term weight maintenance beyond 4 years has not been reported.

• No data exist for use in MASH without NASH diagnosis.

Established label risks

• Boxed warning: Thyroid C-cell tumors. Rodent studies showed dose-dependent C-cell hyperplasia and tumors; human relevance is uncertain but monitoring required per label. Contraindicated in patients with personal/family history of medullary thyroid carcinoma or MEN 2.

• Gastrointestinal: Nausea (44% Wegovy), vomiting, diarrhea, constipation. Dose-dependent; most pronounced during titration.

• Pancreatitis: Rare (reported in clinical trials and postmarket); discontinue if suspected.

• Acute kidney injury: Reported in setting of severe GI volume depletion.

• Gallbladder disease: Increased incidence of cholelithiasis, especially with rapid weight loss.

• Diabetic retinopathy: SUSTAIN-6 showed increased retinopathy complications (HR 1.76, 0.99–3.14), attributed to rapid glycemic improvement.

• Hypoglycemia: Low risk unless combined with insulin or sulfonylureas.

Human-study signals

• SELECT reported serious adverse events in 33.4% of semaglutide vs 36.4% placebo; higher GI event rates.

• Injection-site reactions (mild, self-limited) in 1–2% of clinical trial participants.

Unknowns and product-quality risks

• Human thyroid C-cell tumor risk remains theoretically possible; long-term postmarket surveillance is ongoing.

• Human pregnancy data remain insufficient and animal studies suggest fetal risk. This is not a blanket labeled contraindication: the 2026 Wegovy label says to discontinue treatment used for weight or cardiovascular-risk reduction when pregnancy is recognized, while MASH use during pregnancy is reserved for circumstances in which potential benefit justifies fetal risk.

• Branded products only (Ozempic, Wegovy, Rybelsus); no FDA-approved generic. Compounded semaglutide (including semaglutide sodium) is not FDA-approved and carries risks of impurity, potency variation, and contamination. FDA has issued warnings about compounded semaglutide.

• Delays gastric emptying, potentially reducing rate of absorption of oral medications (especially narrow-therapeutic-index drugs).

• Insulin and sulfonylureas increase hypoglycemia risk; dose adjustment of these agents may be needed.

• Renal impairment: No dose adjustment for mild/moderate; limited data with eGFR below 30 mL/min; caution with severe GI symptoms leading to volume depletion.

• Hepatic impairment: No dose adjustment; limited data in severe hepatic impairment.

• Pregnancy: product and indication matter. Wegovy used for weight or cardiovascular-risk reduction should be discontinued when pregnancy is recognized; for MASH, the label permits use only when potential benefit justifies fetal risk. Other semaglutide labels likewise warn of fetal risk; none should be summarized as a universal formal contraindication.

• FDA boxed warning for thyroid C-cell tumors applies to all semaglutide brands.

• Compounded semaglutide: FDA has repeatedly warned about compounding of "semaglutide sodium" and semaglutide produced without Novo Nordisk authorization. Counterfeit products have been identified.

• WADA: semaglutide is not prohibited, but its markers are included in the 2026 Monitoring Program in- and out-of-competition. Monitoring is not prohibition.

• EU: EMA investigated GLP-1 RA suicide/self-harm signal (2023); found no causal link but recommends continued monitoring.

• Long-term safety >5 years of semaglutide for weight management

• Comparative effectiveness vs tirzepatide in head-to-head obesity trials beyond SURPASS

• Role in primary CV prevention (SELECT was secondary prevention)

• Confirmatory phase 3 data for MASH approval

• Use in adolescents under 12 for obesity (STEP TEENS was 12–18)

• Effects on non-alcoholic steatohepatitis (NASH) with fibrosis stage 3/4

• Databases and registries: PubMed, FDA Drugs@FDA, ClinicalTrials.gov, EMA EPAR, DailyMed, WADA Prohibited List

• Search terms: "semaglutide", "Ozempic", "Rybelsus", "Wegovy", "SUSTAIN", "SELECT", "STEP trial", "OASIS", "SOUL"

• Last searched: 2026-08-06

• Inclusion emphasis: Primary RCT publications, FDA labels, FDA approval announcements, CVOTs

1. Marso SP et al. Semaglutide and cardiovascular outcomes in patients with type 2 diabetes (SUSTAIN-6). N Engl J Med. 2016;375(19):1834-1844. PMID: 27633186. https://doi.org/10.1056/NEJMoa1607141

2. Wilding JPH et al. Once-weekly semaglutide in adults with overweight or obesity (STEP 1). N Engl J Med. 2021;384(11):989-1002. PMID: 34154581. https://doi.org/10.1056/NEJMoa2032183

3. Lincoff AM et al. Semaglutide and cardiovascular outcomes in obesity without diabetes (SELECT). N Engl J Med. 2023;389(24):2221-2232. PMID: 37952131. https://doi.org/10.1056/NEJMoa2307563

4. FDA. Ozempic (semaglutide) injection label. NDA 209637. DailyMed. Accessed 2026-08-06. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=adec4fd2-6858-4c99-91d4-531f5f2a2d79

5. FDA. Wegovy (semaglutide) current label. NDA 215256. Revised 2026. https://www.accessdata.fda.gov/drugsatfda_docs/label/2026/215256s025lbl.pdf

6. FDA. Rybelsus (semaglutide) tablets label. NDA 213051. DailyMed. Accessed 2026-08-06. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=27f15fac-7d98-4114-a2ec-92494a91da98

7. Drucker DJ. Mechanisms of action and therapeutic application of GLP-1 and GIP receptor agonists. Cell Metab. 2018;27(4):740-756. PMID: 29617641. https://doi.org/10.1016/j.cmet.2018.03.001

8. FDA. FDA approves Wegovy (semaglutide) for MASH. August 2025. https://www.fda.gov/drugs/news-events-human-drugs/fda-approves-treatment-serious-liver-disease-known-mash

9. ClinicalTrials.gov. Efficacy and Safety of Semaglutide in Subjects With MASH. NCT04822181. https://clinicaltrials.gov/study/NCT04822181

10. WADA. 2026 Monitoring Program. https://www.wada-ama.org/en/resources/monitoring-program