Head-to-head comparison
| Property | Ipamorelin | Sermorelin |
|---|---|---|
| Category | Muscle & Growth | Muscle & Growth |
| Legal Status | Reclassification Pending | Reclassification Pending |
| Primary Route | subcutaneous | subcutaneous |
| Half-life | ~2 hours | ~10-20 minutes |
| Mol. Weight | 711.85 Da | 3,357.88 Da |
| Side Effects | Headache, Flushing, Injection site pain | Injection site reactions, Facial flushing, Headache |
Key differences
- Receptor target: Ipamorelin is a selective ghrelin receptor (GHS-R) agonist; sermorelin is a GHRH analog that acts on the GHRH receptor.
- Selectivity: Ipamorelin is highly selective for GH release with minimal effects on cortisol, prolactin, or ACTH; sermorelin has a broader hormonal impact through the GHRH pathway.
- GH release pattern: Ipamorelin produces a strong, pulsatile GH spike; sermorelin produces a more physiological, gradual GH elevation.
- FDA history: Sermorelin was previously FDA-approved as Geref for GH deficiency diagnosis (later withdrawn for commercial reasons, not safety); ipamorelin has not been FDA-approved.
- Half-life: Ipamorelin has a half-life of approximately 2 hours; sermorelin has a shorter half-life of 10–20 minutes.
- Side effects: Ipamorelin is considered one of the mildest GH secretagogues with few reported side effects; sermorelin may cause facial flushing, headache, and injection site reactions.
- Stacking: Ipamorelin is often combined with CJC-1295 (a GHRH analog) for synergistic GH release; sermorelin is typically used alone or with GHRP-2/GHRP-6.
The verdict
Neither ipamorelin nor sermorelin is categorically better. Ipamorelin is generally considered cleaner in terms of selectivity, producing strong GH pulses without significant effects on other hormones. Sermorelin has the advantage of prior FDA approval history and a more physiological GH release pattern. The choice depends on the specific research goals and tolerance for off-target hormonal effects.
Frequently asked questions
Ipamorelin is a ghrelin receptor agonist that triggers strong, selective GH pulses, while sermorelin is a GHRH analog that stimulates a more gradual, physiological pattern of GH release. Ipamorelin has minimal impact on cortisol and prolactin; sermorelin acts through a broader hormonal pathway.
Some protocols combine a ghrelin-pathway peptide with a GHRH-pathway peptide for synergistic GH release. However, ipamorelin is more commonly paired with CJC-1295 (another GHRH analog) rather than sermorelin specifically.
Ipamorelin is widely regarded as one of the mildest growth hormone secretagogues, with minimal impact on cortisol, prolactin, and appetite. Sermorelin may cause facial flushing, headache, and injection site reactions in some users.
Sermorelin was previously FDA-approved as Geref for diagnosing growth hormone deficiency. It was withdrawn from the market for commercial reasons, not safety concerns. Ipamorelin has never received FDA approval.
Ipamorelin tends to produce a stronger acute GH spike per dose, while sermorelin produces a more gradual elevation that more closely mimics natural GH secretion patterns. Peak GH levels depend on dosage, timing, and individual response.