Semaglutide
Approved prescription medicine
- Liquid
- 0.050 mL
- Syringe fill
- 5.0 units
A plain English comparison of the three most talked about GLP-1 class peptides: how they work, what the clinical trials actually showed, how they are dosed, and how to pick one. Educational reference only, not medical advice.
| Semaglutide | Tirzepatide | Retatrutide | |
|---|---|---|---|
| Class | GLP-1 receptor agonist | Dual GLP-1 and GIP receptor agonist | Triple GLP-1, GIP, and glucagon receptor agonist |
| Mechanism | Slows gastric emptying, boosts insulin, curbs appetite via GLP-1 pathway. | GLP-1 appetite and insulin effects plus GIP, which improves insulin sensitivity and fat handling. | Adds glucagon agonism on top of GLP-1 and GIP, increasing energy expenditure and lipolysis. |
| Headline trial weight loss | About 15 percent average at 68 weeks (STEP 1, 2.4 mg weekly). | About 20 to 22 percent at 72 weeks (SURMOUNT-1, 15 mg weekly). | About 24 percent at 48 weeks (Phase 2, highest studied dose group). Investigational result. |
| Typical dose cadence | Once weekly, titrate 0.25 to 2.4 mg over 16 to 20 weeks. | Once weekly, titrate 2.5 to 15 mg over 20 weeks. | Once weekly in clinical trials with protocol-directed escalation. Not an approved dosing schedule. |
| Half life | About 7 days | About 5 days | About 6 days |
| Common side effects | Nausea, constipation, fatigue, reflux; usually worst during titration. | Nausea, diarrhea, decreased appetite; often milder than semaglutide at matched loss. | Nausea, elevated heart rate, transient blood sugar swings from glucagon activity. |
| Best fit | First GLP-1 users who want the most published data and steady appetite control. | Users who plateaued on semaglutide or want stronger effect with fewer GI issues. | Clinical research into a triple agonist; it is not currently an approved treatment option. |
Code ANYPEPTIDES15 for 15% off
Use one vial concentration to compare how different weekly doses translate to liquid volume and units on a 100-unit / 1 mL insulin syringe. This is math only, not a dosing recommendation.
Approved prescription medicine
Approved prescription medicine
Investigational, not approved
Branded semaglutide and tirzepatide products are commonly supplied as fixed-dose pens rather than reconstituted vials. Retatrutide remains investigational. Follow the labeled product and a licensed clinician's instructions.
Semaglutide mimics the gut hormone GLP-1. It slows how fast food leaves the stomach, blunts hunger signals in the brain, and helps the pancreas release insulin only when glucose is high. Effect on weight is driven mostly by lower calorie intake.
Tirzepatide hits GLP-1 and adds GIP receptor activity. GIP improves how fat cells store and release energy and appears to soften some GI side effects. In head to head data it produces roughly 5 to 7 percentage points more weight loss than semaglutide at matched cadence.
Retatrutide is a triple agonist: GLP-1, GIP, and glucagon. The glucagon arm raises energy expenditure and drives lipolysis, which is one reason the Phase 2 trial produced a strong weight-loss signal. It remains investigational, with heart-rate changes and long-term safety still under study.
These molecules have been studied as once-weekly injections with gradual escalation to limit side effects. Approved semaglutide and tirzepatide products must follow their specific labels. Retatrutide does not yet have an approved schedule.
Educational content only. Not medical advice. Consult a licensed clinician before starting any peptide protocol.