Weight lossApproved
Tirzepatide
A dual GIP and GLP-1 receptor agonist developed for diabetes and weight management.
Approved as Mounjaro for type 2 diabetes and Zepbound for chronic weight management.
- Routes
- Injection
- Composition
- 39 aa
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Weight LossLegal
Semaglutide
The most studied GLP-1 medicine for weight and metabolic health
Injection, Oral · Prescription
Educational content. This page describes Semaglutide for informational purposes only and is not medical advice, diagnosis, or treatment. Consult a licensed provider before starting, stopping, or modifying any therapy.
Researched and maintained by the PepHookup team. Regulatory status last verified April 30, 2026.
- Primary Use
- A GLP-1 receptor agonist that slows gastric emptying and reduces appetite signaling.
- Administration
- injection, oral
- Typical Cycle
- Ongoing
- Legal Status
- Legal
Key Benefits
Cardiovascular Risk Reduction
The 17,604-person SELECT trial showed a 20% lower rate of cardiovascular death, heart attack, or stroke in adults with established heart disease and obesity but no diabetes (hazard ratio 0.80).[8]
What is Semaglutide?
Semaglutide is a glucagon-like peptide-1 (GLP-1) receptor agonist, a 31-amino-acid peptide engineered from the human GLP-1 hormone. It carries two amino acid substitutions (Aib at position 8 and Arg at position 34) and a fatty diacid chain attached at lysine 26. That chain binds tightly to blood albumin, which protects the molecule from rapid breakdown and stretches its half-life to roughly one week, enabling once-weekly injection.
It reached the market first as Ozempic (2017) for type 2 diabetes, then as oral Rybelsus (2019) for diabetes, and as Wegovy (2021) for chronic weight management. A higher-dose Wegovy formulation (7.2 mg) was approved in 2025. Wegovy's obesity approval rested on the STEP phase 3 program, which enrolled thousands of participants, and semaglutide has since become the most extensively studied GLP-1 medicine in clinical use.
How Does It Work?
Semaglutide imitates GLP-1, an incretin hormone the gut releases after eating. By binding GLP-1 receptors in the pancreas, it boosts insulin release only when blood glucose is elevated and dampens glucagon, so it lowers blood sugar with a low intrinsic risk of hypoglycemia.
Its weight effects are driven largely by the brain. Semaglutide reaches GLP-1 receptors in the hypothalamus and area postrema, regions that govern hunger and fullness, reducing food intake. It also slows gastric emptying, so meals leave the stomach more slowly and satiety lasts longer.
Beyond glucose and appetite, semaglutide reduces systemic inflammation and improves cardiometabolic markers. In the STEP-HFpEF trial it cut C-reactive protein by about 44% and improved heart failure symptoms and walking distance, and in SELECT it lowered cardiovascular events in people with heart disease.
Quick Facts
The most studied GLP-1 medicine for weight and metabolic health
- Primary Use
- A GLP-1 receptor agonist that slows gastric emptying and reduces appetite signaling.
- Administration
- injection, oral
- Typical Cycle
- Ongoing
- Categories
- weight loss
- Legal Status
- Available for compounding
Mechanism of Action
Semaglutide is an albumin-bound, long-acting GLP-1 receptor agonist. It enhances glucose-dependent insulin secretion and suppresses glucagon in the pancreas, acts on hypothalamic and brainstem appetite centers to reduce food intake, slows gastric emptying to prolong satiety, and lowers inflammation, together producing weight loss and broad cardiometabolic benefit.
Clinical Evidence
STEP 1: Obesity Without Diabetes
Randomized, double-blind, placebo-controlled, phase 31,961 adults with obesity or overweight, no diabetes
Mean weight loss of 14.9% with semaglutide 2.4 mg versus 2.4% with placebo at 68 weeks. 86.4% lost at least 5% and 50.5% lost at least 15%.
Wilding JPH, Batterham RL, Calanna S, et al. · N Engl J Med, 384(11):989-1002 (2021) · PubMed
STEP 2: Type 2 Diabetes
Randomized, double-blind, double-dummy, placebo-controlled, phase 31,210 adults with overweight or obesity and type 2 diabetes
Mean weight loss of 9.6% with semaglutide 2.4 mg versus 3.4% with placebo at 68 weeks, alongside improved glycemic control.
Davies M, Færch L, Jeppesen OK, et al. · Lancet, 397(10278):971-984 (2021) · PubMed
SELECT: Cardiovascular Outcomes
Randomized, double-blind, placebo-controlled event-driven CV outcomes trial17,604 adults with prior cardiovascular disease and overweight/obesity, no diabetes
Major adverse cardiovascular events occurred in 6.5% on semaglutide versus 8.0% on placebo (hazard ratio 0.80) over a mean 39.8 months.
Lincoff AM, Brown-Frandsen K, Colhoun HM, et al. · N Engl J Med, 389(24):2221-2232 (2023) · PubMed
FLOW: Diabetic Kidney Disease
Randomized, double-blind, placebo-controlled outcomes trial3,533 adults with type 2 diabetes and chronic kidney disease
24% lower risk of major kidney disease events (hazard ratio 0.76) and a 20% lower risk of death from any cause; the trial was stopped early for efficacy.
Perkovic V, Tuttle KR, Rossing P, et al. · N Engl J Med, 391(2):109-121 (2024) · PubMed
ESSENCE: Liver Disease (MASH)
Randomized, double-blind, placebo-controlled, phase 3 (week-72 interim)800 adults with biopsy-confirmed MASH and fibrosis stage 2-3
Steatohepatitis resolved without fibrosis worsening in 62.9% on semaglutide versus 34.3% on placebo; fibrosis improved in 36.8% versus 22.4%.
Sanyal AJ, Newsome PN, Kliers I, et al. · N Engl J Med, 392(21):2089-2099 (2025) · PubMed
Dosing & Administration
start low, go slow
Subcutaneous Injection (Wegovy, weight management)
- Dosage
- 0.25 mg titrated to 2.4 mg
- Frequency
- Once weekly
- Cycle
- Ongoing
Subcutaneous Injection (Ozempic, type 2 diabetes)
- Dosage
- 0.25 mg titrated to 1.0–2.0 mg
- Frequency
- Once weekly
- Cycle
- Ongoing
Oral (Rybelsus, type 2 diabetes)
- Dosage
- 3 mg titrated to 7–14 mg
- Frequency
- Once daily
- Cycle
- Ongoing
Subcutaneous Injection (Wegovy, weight management): Standard 16-week escalation: 0.25, 0.5, 1.0, 1.7, then 2.4 mg, each step held for 4 weeks. A 7.2 mg high-dose formulation was approved in 2025.
Subcutaneous Injection (Ozempic, type 2 diabetes): Approved for glycemic control in type 2 diabetes, not weight management. The 0.25 mg starting dose is for titration only and is not therapeutic.
Oral (Rybelsus, type 2 diabetes): Take on an empty stomach with no more than 4 oz of water, at least 30 minutes before food, drink, or other medication. Approved for diabetes, not weight loss.
Dosing, formulation, and titration speed are determined by a licensed provider based on indication, tolerance, and treatment goals. The gradual escalation schedule exists to limit gastrointestinal side effects and should not be rushed.
If a weekly dose is missed, it can be taken within 5 days. If more than 5 days have passed, skip it and resume the regular schedule.
Injections are rotated among the abdomen, thigh, and upper arm. Wegovy (weight management) and Ozempic (diabetes) are not interchangeable at matching milligram amounts because their approved dose ranges differ.
Side Effects & Safety
Common
- Nausea: The most frequent effect, usually mild to moderate, transient, and reduced by slow dose escalation and smaller meals.
- Diarrhea: Typically mild and self-limiting, most common during dose increases.
- Vomiting: More likely during titration and with very large or high-fat meals.
- Constipation: Often managed with hydration, fiber, and physical activity.
Uncommon
- Gallbladder problems (gallstones): Rapid weight loss raises gallstone risk; report persistent upper-right abdominal pain.
- Injection site reactions: Mild redness, itching, or tenderness that usually resolves on its own.
Rare
- Acute pancreatitis: Discontinue and seek care for severe, persistent abdominal pain; resume only after pancreatitis is excluded.
Safety Profile
Semaglutide has one of the largest safety datasets of any peptide medicine, with tens of thousands of participants across the STEP, SELECT, FLOW, and SUSTAIN programs. Adverse events are predominantly gastrointestinal and tend to ease as the body adjusts to each dose.
Gastrointestinal events drive most discontinuations. In STEP 1, 4.5% of the semaglutide group stopped due to GI events versus 0.8% on placebo. In SELECT, 16.6% discontinued for any adverse event versus 8.2% on placebo, mostly GI in nature.
Rodent studies showed thyroid C-cell tumors, which underlies a boxed warning, though a causal link in humans has not been established. Because some weight loss is lean mass, providers often pair therapy with adequate protein intake and resistance exercise.
Contraindications
- Personal or family history of medullary thyroid carcinoma (MTC)
- Multiple Endocrine Neoplasia syndrome type 2 (MEN2)
- Pregnancy or planning pregnancy (discontinue at least 2 months prior)
- Prior serious hypersensitivity reaction to semaglutide or its components
- Caution with a history of pancreatitis, gastroparesis, or severe gastrointestinal disease
Compare with Similar Peptides
| Peptide | Primary Use | Administration | Cycle Length | Key Differentiator |
|---|---|---|---|---|
| Semaglutide | Weight Management & Metabolic Health | Injection (weekly), Oral (daily) | Ongoing | The most clinically validated GLP-1 medicine, with outcomes data spanning weight, heart, kidney, and liver disease |
| Tirzepatide | Weight Loss & Type 2 Diabetes | Injection (weekly) | Ongoing | Only dual GIP/GLP-1 agonist; the deepest weight loss of any approved obesity drug, up to about 21% of body weight |
| Tesamorelin | Visceral Fat & GHRH Signaling | Subcutaneous Injection | Ongoing daily | The only FDA-approved GHRH analog, with Phase III data in over 800 patients, documented liver-fat reduction, and physiologic pulsatile GH release |
| Ipamorelin | GH stimulation for body composition and recovery | Subcutaneous injection (1-3x daily) | Determined by provider | The most selective GH secretagogue in preclinical work: a clean GH pulse without the cortisol, prolactin, or appetite effects of older GHRPs |
| AOD-9604 | Fat Reduction (efficacy unproven in humans) | Injection (clinic practice); oral and IV in trials | Set by provider; no standard exists | Reproduces growth hormone's fat-burning domain without raising IGF-1 or impairing glucose, but failed to beat placebo for weight loss in human trials |
Regulatory Status
FDA-Approved
PrescriptionThis peptide is an FDA-approved drug available via standard prescription.
Regulatory Detail
Multiple FDA approvals: Ozempic (2017, diabetes), Rybelsus (2019, oral diabetes), Wegovy (2021, weight loss), Wegovy HD (2025, higher dose). On April 30, 2026 the FDA proposed removing semaglutide from the 503B bulks list and tightened documentation requirements for 503A compounding. Public comment runs through June 29, 2026.
FDA Action History
FDA proposed excluding semaglutide from the 503B bulks list and clarified 503A documentation standards
FDA approved Wegovy HD (semaglutide 7.2 mg) for weight loss and maintenance
FDA approved Wegovy (semaglutide 2.4 mg injection) for chronic weight management
FDA approved Rybelsus (oral semaglutide) for type 2 diabetes
FDA approved Ozempic (semaglutide injection) for type 2 diabetes
What do these terms mean?
- 503A compounding
- Licensed pharmacies that prepare custom prescriptions for individual patients based on a physician's order. 503A is the section of the federal law that governs them.
- 503B outsourcing
- FDA-registered facilities that compound in larger batches under stricter federal oversight (closer to a manufacturer than a pharmacy). Used mostly by hospitals and clinics.
- Bulk drug substance
- The active pharmaceutical ingredient a compounder starts with, before it's made into a finished medication.
- Category 1
- Interim bucket for bulk substances that have been nominated and don't appear to present significant safety risks. 503A pharmacies may compound them under FDA enforcement discretion while the agency continues its review. Not the same as FDA approval.
- Category 2
- Bulk substances the FDA has flagged for significant safety risks. 503A compounding carries FDA enforcement risk, so most pharmacies decline to prepare them and many physicians hesitate to prescribe them.
- PCAC
- Pharmacy Compounding Advisory Committee. The FDA advisory committee that reviews nominated bulk substances and recommends whether they belong in Category 1, Category 2, or on the final 503A Bulks List.
Last verified April 30, 2026. PepHookup tracks public FDA actions. This is not legal or medical advice.
Frequently Asked Questions
Research & References
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