Selective Growth Hormone Secretagogue
A synthetic pentapeptide GHRP that selectively stimulates GH release via GHS-R1a receptors without elevating cortisol, prolactin, or appetite — the cleanest GHRP in the research toolkit.
Research Disclaimer: This guide is for educational and research purposes only. Ipamorelin is not FDA-approved for human use. All information is based on published research and should not be construed as medical advice. Consult a qualified healthcare professional before considering any peptide protocol.
Ipamorelin is a synthetic pentapeptide that acts as a selective agonist at the growth hormone secretagogue receptor type 1a (GHS-R1a), the same receptor activated by the endogenous hormone ghrelin. When Ipamorelin binds GHS-R1a on somatotroph cells in the anterior pituitary, it triggers a calcium-dependent signaling cascade that stimulates GH secretion.
What distinguishes Ipamorelin from earlier GHRPs (GHRP-6, GHRP-2) is its selectivity. Earlier GHRPs activate GHS-R1a but also engage off-target receptors that elevate cortisol, prolactin, and ACTH. Ipamorelin's structure (Aib-His-D-2-Nal-D-Phe-Lys-NH₂) confers high selectivity for GHS-R1a with minimal off-target activity, producing a clean GH pulse without the hormonal side effects of older GHRPs.
GHRH analogues (Sermorelin, CJC-1295, Tesamorelin) act on GHRH receptors to prime the pituitary. GHRPs (Ipamorelin, GHRP-6) act on GHS-R1a receptors to trigger GH release. The two pathways are synergistic — combining a GHRH analogue with Ipamorelin produces 2–10× greater GH release than either alone. This is the mechanistic basis for the CJC-1295 + Ipamorelin combination protocol.
GH is predominantly secreted during slow-wave sleep (SWS). Ipamorelin's pre-sleep administration amplifies the natural nocturnal GH pulse, improving sleep quality and GH release simultaneously. Research subjects consistently report improved sleep depth within 1–2 weeks.
Evidence: Moderate (sleep lab studies, GH pulse data)GH axis activation via Ipamorelin promotes lipolysis and lean mass preservation. When stacked with CJC-1295, the synergistic GH release produces measurable improvements in body composition including reduced visceral fat and increased lean body mass over 8–12 weeks.
Evidence: Moderate (clinical studies, combination protocols)Elevated GH and downstream IGF-1 accelerate collagen synthesis, muscle protein synthesis, and tissue repair. Ipamorelin is studied in recovery protocols following musculoskeletal injury, with research subjects reporting faster recovery and reduced soreness.
Evidence: Early-stage (preclinical + observational)Age-related decline in GH secretion (somatopause) is well-documented. Ipamorelin is studied as a means to partially restore youthful GH pulsatility. Its selective profile — without cortisol or prolactin elevation — makes it particularly attractive for long-term anti-aging protocols.
Evidence: Early-stage (preclinical + observational)Understanding where Ipamorelin fits in the GH secretagogue landscape requires comparing it to both GHRH analogues (which it complements) and older GHRPs (which it largely supersedes in research protocols).
| Property | Ipamorelin | CJC-1295 | Sermorelin |
|---|---|---|---|
| Class | GHRP (ghrelin mimetic) | GHRH analogue | GHRH analogue |
| Receptor | GHS-R1a | GHRHR | GHRHR |
| Half-life | ~2 hours | ~30 min (no DAC) | ~10–20 min |
| GH release pattern | Pulsatile (selective) | Pulsatile | Pulsatile |
| Cortisol elevation | Minimal | None | None |
| Prolactin elevation | Minimal | None | None |
| Appetite stimulation | Mild | None | None |
| Synergy with GHRH | Yes — pairs with CJC-1295 | Pairs with Ipamorelin | Pairs with GHRP-2/6 |
| FDA status | Not approved | Not approved | Withdrawn 2008 |
Ipamorelin's greatest utility is as a stacking partner with GHRH analogues. The GHRH + GHRP combination exploits two complementary receptor pathways for synergistic GH release. The following protocols represent the most studied combinations in the research literature.
Ipamorelin has one of the most favorable safety profiles among GH secretagogues, primarily because of its receptor selectivity. The absence of significant cortisol, prolactin, or ACTH elevation distinguishes it from GHRP-6 and GHRP-2.
| Effect | Frequency | Severity | Notes |
|---|---|---|---|
| Water retention | Common | Mild | Typically resolves after 2–4 weeks as the body adapts to elevated GH. |
| Injection site reactions | Common | Mild | Redness, swelling, or pain at the injection site. Rotate injection sites to minimize. |
| Flushing / warmth | Common | Mild | Transient facial flushing or warmth, typically within 30 minutes of injection. Resolves spontaneously. |
| Headache | Uncommon | Mild | Reported in a subset of subjects. Possibly GH-mediated fluid shifts. Usually resolves within the first few weeks. |
| Mild appetite stimulation | Uncommon | Mild | Less pronounced than GHRP-6. Ipamorelin has partial ghrelin mimetic activity but significantly less appetite stimulation than older GHRPs. |
| Carpal tunnel symptoms | Rare | Moderate | Associated with high doses and/or prolonged use. GH-mediated fluid retention in the carpal tunnel. Dose reduction typically resolves symptoms. |
| Cortisol elevation | Minimal | Low | Ipamorelin's key advantage over GHRP-6: cortisol elevation is minimal and not considered clinically significant at standard doses. |
| Pituitary desensitization | Rare (with cycling) | Moderate | Continuous use beyond 12 weeks without breaks may reduce receptor sensitivity. Standard cycling protocols (8–12 weeks on, 4 weeks off) prevent this. |
| Protocol | Dose | Frequency | Cycle |
|---|---|---|---|
| Conservative (solo) | 100 mcg | 1× daily (pre-sleep) | 8–12 weeks |
| Standard (solo) | 200 mcg | 2× daily | 8–12 weeks |
| Stacked with CJC-1295 | 100 mcg | 2–3× daily | 3–6 months |
| Sleep optimization | 200–300 mcg | 1× daily (pre-sleep) | 8–12 weeks |
For the full Ipamorelin dosage guide including reconstitution instructions and concentration calculator, see the Ipamorelin Dosage Guide.
Ipamorelin is a selective growth hormone secretagogue receptor (GHSR) agonist — a synthetic pentapeptide that mimics the action of ghrelin on the pituitary gland. Unlike GHRH analogues (Sermorelin, CJC-1295, Tesamorelin), Ipamorelin acts through a completely different receptor pathway (GHS-R1a) to stimulate GH release. Its key advantage is selectivity: it produces a clean GH pulse without significantly elevating cortisol, prolactin, or ACTH, which distinguishes it from older GHRPs like GHRP-6.
Ipamorelin is a GHRP (growth hormone-releasing peptide), not a GHRH analogue. It belongs to the ghrelin mimetic class and acts on GHS-R1a receptors. GHRH analogues (Sermorelin, CJC-1295, Tesamorelin) act on GHRH receptors. The two classes work through complementary pathways, which is why stacking Ipamorelin with a GHRH analogue like CJC-1295 produces synergistic GH release.
The most widely used Ipamorelin dose is 100–300 mcg per injection, administered 2–3 times daily. A conservative starting protocol is 100 mcg once daily before sleep. When stacked with CJC-1295, doses of 100 mcg each, injected simultaneously 2–3 times daily, are standard. Ipamorelin is typically administered via subcutaneous injection.
Ipamorelin is considered a second-generation GHRP with a significantly cleaner profile than GHRP-6. GHRP-6 stimulates GH release but also substantially elevates cortisol, prolactin, and ACTH, and causes significant appetite stimulation via ghrelin pathways. Ipamorelin produces selective GH release with minimal effect on cortisol, prolactin, or appetite, making it the preferred GHRP for most research protocols.
Yes — Ipamorelin + CJC-1295 is the most studied GH secretagogue combination. CJC-1295 (GHRH receptor) and Ipamorelin (GHS-R1a receptor) work through complementary pathways, producing synergistic GH pulses 2–10× greater than either peptide alone. They are typically injected simultaneously at the same injection site. The combination is considered the gold standard for GH optimization research.
Ipamorelin is generally well-tolerated. Common side effects include mild water retention (first 2–4 weeks), injection site reactions, and occasional headache or flushing. Unlike GHRP-6, Ipamorelin does not significantly increase cortisol, prolactin, or appetite. Rare side effects include carpal tunnel symptoms at high doses and mild hypersensitivity reactions. Pituitary desensitization is possible with continuous use beyond 12 weeks without cycling.
Improved sleep quality and deeper slow-wave sleep are typically reported within 1–2 weeks. Increased energy and improved recovery are noticed within 2–4 weeks. Body composition changes (increased lean mass, reduced body fat) require 8–12 weeks of consistent use. Measurable IGF-1 elevation is typically seen within 4–6 weeks. When stacked with CJC-1295, results are generally more pronounced and occur faster.
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Shop Ipamorelin at Purgo LabsMedical Disclaimer: All content on this site is for educational and research purposes only. Research peptides are not FDA-approved for human use. Always consult a qualified healthcare professional before considering any peptide or supplement protocol. Nothing on this site constitutes medical advice, diagnosis, or treatment.