Educational reference only. Informational material drawn from peer-reviewed literature. Not medical advice and not a recommendation to use, dose, or modify any therapy. Decisions about hormone therapy should be made with a qualified healthcare provider.
Overview
Overview
Semaglutide is a synthetic GLP-1 (glucagon-like peptide-1) receptor agonist, a class of peptide drugs that mimic the action of the endogenous incretin hormone GLP-1. It is one of the most consequential pharmacological developments of the past decade, with one of the strongest evidence bases for efficacy and safety of any drug currently in widespread clinical use.
Semaglutide is marketed under three brand names by Novo Nordisk:
- Ozempic: Type 2 diabetes (with cardiovascular risk reduction); once-weekly subcutaneous injection
- Wegovy: Chronic weight management (with cardiovascular risk reduction in obesity); once-weekly subcutaneous injection
- Rybelsus: Type 2 diabetes; daily oral tablet
All three contain the same active molecule at different doses and formulations. Wegovy (2.4 mg) is the highest-dose formulation, approved specifically for chronic weight management.
Approval timeline:
- 2017: Ozempic approved for type 2 diabetes
- 2019: Rybelsus (oral) approved for type 2 diabetes
- 2020: Ozempic approved for cardiovascular risk reduction in T2D
- 2021: Wegovy approved for chronic weight management
- 2024: Wegovy approved for cardiovascular risk reduction in adults with obesity and established cardiovascular disease (based on SELECT trial)
- 2025: Wegovy oral formulation approved
Forms
Available forms & half-lives
| Form | Approximate half-life |
|---|---|
| Subcutaneous injection (Ozempic, Wegovy) | ~165 hours (~7 days) |
| Oral tablet (Rybelsus) | ~165 hours |
What it does
Main effects
- Substantial weight loss: STEP 1 demonstrated mean −14.9% body weight at 68 weeks on 2.4 mg weekly PMID: 33567185; sustained at 4 years in SELECT extension
- Glycemic control in type 2 diabetes: glucose-dependent insulin secretion + glucagon suppression; minimal hypoglycemia risk as monotherapy
- 20% MACE reduction in adults with overweight/obesity and established CVD without diabetes PMID: 37952131, SELECT trial; cardiovascular benefit appeared earlier than weight loss alone would predict
- Appetite suppression and reduced "food noise" via hypothalamic and brainstem GLP-1 receptors
- Delayed gastric emptying: contributes to satiety and postprandial glucose control
- Modest blood pressure reduction, improved lipid profile, reduced inflammation markers
- Active investigation across additional indications: HFpEF, CKD in T2D, MASH, addiction medicine, Alzheimer's disease
What to watch for
Common side effects
- Gastrointestinal effects (nausea ~44%, diarrhea ~30%, constipation ~24%, vomiting ~24%, abdominal pain ~20%): dose-dependent, typically improve over time, primary reason for discontinuation
- Lean mass loss: approximately 25–40% of weight lost is lean mass; resistance training and adequate protein intake are noted considerations
- Pancreatitis: rare but documented; FDA boxed warning context
- Gallbladder disease (cholelithiasis, cholecystitis): modestly increased risk with rapid weight loss
- Medullary thyroid carcinoma: boxed warning based on rodent studies; contraindicated with personal/family history of MTC or MEN 2
- Acute kidney injury: usually secondary to dehydration from GI effects
- Heart rate increase (modest, 1–4 bpm)
- Hypoglycemia in combination with insulin or sulfonylureas (low risk as monotherapy)
- Weight regain on discontinuation: STEP 4 demonstrated that weight loss is largely reversed when stopping; treatment is conceptualized as chronic
- Compounded semaglutide quality concerns: during shortages, compounded products have raised concerns about identity, concentration, purity, and salt-form variability
Key facts
Key facts worth knowing
- Semaglutide is a 94% structurally homologous analog of human GLP-1, modified to resist degradation by DPP-4 (the enzyme that rapidly clears endogenous GLP-1) and to bind albumin (extending half-life dramatically). The result is a peptide with a ~165-hour half-life (allowing once-weekly dosing) compared to native GLP-1's half-life of approximately 2 minutes.
- Clinical efficacy is substantial. In the STEP 1 trial, participants without diabetes on once-weekly 2.4 mg semaglutide lost an average of 14.9% of body weight at 68 weeks versus 2.4% on placebo. The SELECT trial (17,604 adults with established CVD and overweight or obesity, without diabetes) demonstrated 20% reduction in major adverse cardiovascular events (MACE): cardiovascular death, nonfatal MI, or nonfatal stroke. PMID: 33567185PMID: 37952131
- The SELECT cardiovascular benefit was striking and unprecedented. It was the first time a weight-loss medication had demonstrated cardiovascular risk reduction in patients without diabetes. The 20% MACE reduction occurred regardless of baseline BMI, age, sex, race, or renal function. There was also a 15% reduction in cardiovascular death and 19% reduction in all-cause mortality. PMID: 37952131
- Beyond weight and cardiovascular benefits, semaglutide has demonstrated benefits in heart failure with preserved ejection fraction (HFpEF), chronic kidney disease in T2D, metabolic dysfunction-associated steatohepatitis (MASH), and is being investigated for additional indications including addiction medicine, Alzheimer's disease, and various inflammatory conditions.
- The compound has a well-characterized side effect profile dominated by gastrointestinal effects (nausea, vomiting, diarrhea, constipation), with most adverse effects mild-to-moderate and dose-dependent. Severe adverse effects are uncommon at therapeutic doses.
- WADA status is currently NOT prohibited: GLP-1 receptor agonists are not on the WADA Prohibited List as of current update. This distinguishes semaglutide from anabolic-androgenic steroids and many other compounds in performance enhancement contexts.
Legal status
Legal status
FDA-approved prescription medication. Not a controlled substance.