Head-to-head comparison
| Property | Ipamorelin | Tesamorelin |
|---|---|---|
| Category | Muscle & Growth | Muscle & Growth |
| Legal Status | Reclassification Pending | Prescription |
| Primary Route | subcutaneous | subcutaneous |
| Half-life | ~2 hours | ~26-38 minutes |
| Mol. Weight | 711.85 Da | 5,135.89 Da |
| Side Effects | Headache, Flushing, Injection site pain | Injection site reactions (pain, redness), Joint pain, Nausea |
Key differences
- Mechanism: Ipamorelin binds the ghrelin/GHS-R1a receptor to trigger pulsatile GH release; tesamorelin binds the GHRH receptor on pituitary somatotroph cells to stimulate GH synthesis and secretion.
- Legal status: Tesamorelin is FDA-approved as Egrifta for HIV-associated lipodystrophy and available by prescription; ipamorelin is under FDA reclassification review and was previously available as a research peptide.
- Evidence base: Tesamorelin has Phase III clinical trial data (LIPO-010, LIPO-011) demonstrating 15.2% trunk fat reduction; ipamorelin has Phase II data showing dose-dependent GH release with a favorable safety profile.
- Dosing: Ipamorelin is typically dosed at 200-300 mcg subcutaneously 2-3 times daily; tesamorelin is dosed at 1-2 mg subcutaneously once daily (FDA-approved dose is 2 mg).
- Side effects: Ipamorelin has minimal impact on cortisol, prolactin, or appetite; tesamorelin's common side effects include joint pain, nausea, and peripheral edema documented in Phase III trials.
- Half-life: Ipamorelin has a half-life of approximately 2 hours; tesamorelin has a much shorter half-life of approximately 26-38 minutes but is dosed once daily at higher amounts.
- Cost: Tesamorelin as a branded prescription drug (Egrifta) is significantly more expensive than ipamorelin from compounding pharmacies, reflecting its FDA-approved status.
The verdict
Tesamorelin has the strongest clinical evidence of the two, with FDA approval and Phase III data demonstrating visceral fat reduction and emerging cognitive benefits. Ipamorelin offers a milder GH-releasing profile with fewer hormonal side effects but lacks the level of clinical validation tesamorelin has achieved. The choice between them depends on whether FDA-approved status and robust clinical data outweigh the convenience and selectivity of ipamorelin's receptor profile.
Frequently asked questions
Because ipamorelin acts on the ghrelin receptor and tesamorelin acts on the GHRH receptor, they stimulate GH release through different pathways and are sometimes combined in clinical protocols. This is mechanistically similar to stacking ipamorelin with CJC-1295. No controlled trials have studied this specific combination.
Tesamorelin has direct Phase III clinical evidence showing significant visceral fat reduction (15.2% trunk fat decrease). Ipamorelin's effects on body composition are supported by Phase II data and anti-aging clinic experience but lack the same level of controlled trial evidence for fat loss specifically.
Both have favorable safety profiles. Tesamorelin's safety is better characterized through Phase III trials, with joint pain, nausea, and edema as common side effects. Ipamorelin is considered one of the mildest GHRPs because it does not raise cortisol or prolactin, but its safety data comes primarily from Phase II studies.
Tesamorelin was developed by Theratechnologies and underwent the full FDA approval process including Phase III trials for a specific indication (HIV-associated lipodystrophy). Ipamorelin did not complete the same regulatory pathway. FDA approval reflects the investment in clinical trials for a defined medical use, not necessarily superiority.
Both peptides increase IGF-1 levels through their stimulation of growth hormone release. Tesamorelin clinical trials demonstrated clinically meaningful, dose-dependent GH and IGF-1 increases. Ipamorelin Phase II data similarly showed dose-dependent GH release that would elevate IGF-1.