Semaglutide is the active ingredient in Ozempic, Wegovy, and Rybelsus, and in the compounded semaglutide available through telehealth for $147–200/month. This comprehensive guide covers everything: mechanism, dosing, efficacy, side effects, access, and cost.
What Is Semaglutide?
Semaglutide is a GLP-1 receptor agonist, a synthetic molecule that mimics the glucagon-like peptide-1 hormone naturally produced in your gut after eating. It was developed by Novo Nordisk and first approved by the FDA in 2017 for type 2 diabetes (as Ozempic). The weight management formulation (Wegovy, at 2.4mg weekly) was approved in 2021.
What makes semaglutide remarkable compared to the natural GLP-1 hormone: the natural hormone has a half-life of about 2 minutes. Semaglutide's half-life is approximately one week, which is why once-weekly dosing is effective.
How Semaglutide Works
Appetite suppression: Semaglutide activates GLP-1 receptors in the hypothalamus (the brain's appetite control center) and the brainstem. This reduces hunger signals and decreases "food noise", the constant preoccupation with eating that characterizes many people with obesity. Many patients describe the effect as "food just stopped being interesting."
Slowed gastric emptying: Food stays in the stomach longer, prolonging fullness after meals. This also contributes to the nausea side effect, especially at higher doses.
Blood sugar regulation: Stimulates insulin release in a glucose-dependent manner (only when blood sugar is elevated), suppresses glucagon, and reduces post-meal blood sugar spikes. This makes it effective for type 2 diabetes without the hypoglycemia risk of some other diabetes medications.
Semaglutide Brand Names
| Brand | Indication | Doses | Administration |
|---|---|---|---|
| Ozempic | Type 2 diabetes | 0.5, 1, 2mg weekly | Subcutaneous injection |
| Wegovy | Weight management | Up to 2.4mg weekly | Subcutaneous injection |
| Rybelsus | Type 2 diabetes | 3, 7, 14mg daily | Oral tablet |
| Compounded | Any qualifying indication | Customized | Subcutaneous injection |
Clinical Evidence: How Well Does It Work?
The STEP clinical trial program is the landmark evidence base for semaglutide in weight management:
- STEP 1: 2.4mg semaglutide vs placebo, 14.9% average weight loss at 68 weeks. 86% of semaglutide group lost 5%+ body weight. 69% lost 10%+. 50% lost 15%+. 32% lost 20%+.
- STEP 4: Demonstrated weight regain after discontinuation, critical evidence that long-term use is needed to maintain results.
- SELECT trial: Semaglutide 2.4mg reduced major adverse cardiovascular events by 20% in high-risk cardiovascular patients with overweight/obesity but without diabetes. This led to FDA approval for cardiovascular risk reduction, a landmark indication.
Dosing Schedule
| Week | Dose |
|---|---|
| Weeks 1–4 | 0.25mg weekly |
| Weeks 5–8 | 0.5mg weekly |
| Weeks 9–12 | 1.0mg weekly |
| Weeks 13–16 | 1.7mg weekly |
| Week 17+ | 2.4mg weekly (maintenance) |
Side Effects
See the complete side effects guide for full detail. The most common:
- Nausea (40–50% of patients, especially during dose escalation)
- Constipation (~25–35%)
- Diarrhea (~20–30%)
- Vomiting (~15–25% at higher doses)
- Fatigue (especially early)
Who Should Not Take Semaglutide
- Personal or family history of medullary thyroid carcinoma
- Multiple endocrine neoplasia syndrome type 2
- Prior serious hypersensitivity to semaglutide
- Pregnancy (or planning pregnancy within 2 months)
Cost and Access
Brand-name Wegovy: $935–1,050/month without insurance. Compounded semaglutide through telehealth: $147–200/month. See the full cost guide for complete pricing breakdown and access options.