Growth Hormone
CAS
170851-70-4
Molecular Weight
711
Da
A selective synthetic peptide that stimulates growth hormone release from the pituitary gland, with minimal effect on cortisol or prolactin in early studies. Popular in longevity and performance circles. Its one completed efficacy trial, in post-surgical gut recovery, missed its primary endpoint, and it has never been tested in humans for body composition, recovery, or aging. Often paired with CJC-1295, a combination that has not been studied in a controlled trial.
Injectable
Intranasal Suitable
Yes
Research Compound
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Community signal is generally positive but methodologically murky. Ipamorelin is almost universally discussed in combination with CJC-1295 rather than as a standalone compound, making isolated attribution nearly impossible. The CJC/Ipa stack is one of the most commonly referenced peptide combinations in biohacking forums. Sleep quality, recovery, and mild body composition changes are the most frequently cited benefits. Side effect reports are notably rare compared to other GH secretagogues, which the community attributes to its GH-specific mechanism without cortisol or prolactin elevation. Dosing timing debates, pre-bed vs pre-workout, are a recurring community discussion.
Ipamorelin is a synthetic pentapeptide (a chain of five amino acids) and a selective growth hormone secretagogue. It was developed by Novo Nordisk in the 1990s and described in 1998 as the first selective GH secretagogue: in early studies it raised growth hormone without the cortisol and prolactin increases seen with older compounds like GHRP-6. Its only completed randomized efficacy trial, a Phase 2 study of 117 patients recovering from bowel surgery, did not show a statistically significant benefit over placebo (Beck et al., 2014), and clinical development did not continue.
Ipamorelin mimics ghrelin, binding the ghrelin receptor (GHS-R1a) in the pituitary gland and triggering a pulse of growth hormone release. What distinguishes it from GHRP-2 or GHRP-6 is selectivity: in early animal and human pharmacology studies, it raised GH with little effect on cortisol or prolactin. It is often paired with a GHRH analog like CJC-1295 on the rationale that the two act on different receptors. That rationale is mechanistic and has not been tested as a combination in a controlled human trial.
Ipamorelin is marketed and used for raising growth hormone, lean muscle, sleep quality, fat metabolism, and anti-aging. None of these uses have been tested in published human trials. The only human efficacy research is a single Phase 2 trial in postoperative ileus, which did not meet its primary endpoint. Supporting evidence for the marketed uses comes from animal studies and the general biology of growth hormone.
While ipamorelin has a relatively favorable safety profile compared to other GH secretagogues, considerations include: potential suppression of natural GH axis with prolonged use, water retention, tingling or numbness at injection sites, and headaches particularly during initial use. Individuals with active malignancies should avoid GH-stimulating peptides as growth hormone can theoretically accelerate tumor growth. Not recommended during pregnancy or breastfeeding. Long-term effects in humans are not well established. No long-term human safety data exist. Large population studies link both low and high IGF-1 levels to higher mortality, and higher IGF-1 to greater disease risk in older adults, so raising the GH/IGF-1 axis in healthy people is not established as beneficial. Products sold online as “research use only” are unverified; ipamorelin products were named in FDA warning letters to online sellers in August 2026.
Injectable (subcutaneous). Typically sold as a lyophilized powder requiring reconstitution with bacteriostatic water. Some oral and nasal formulations exist but bioavailability data is limited and injectable remains the standard form used in research and clinical compounding contexts.
Not FDA approved for any use. FDA placed ipamorelin in Category 2 (substances that may present significant safety risks) in 2023. After the 503A nominations were withdrawn in 2024, the FDA’s Pharmacy Compounding Advisory Committee reviewed ipamorelin on October 29, 2024, evaluated for growth hormone deficiency and postoperative ileus, and voted 0-12 (1 abstention) against adding it to the 503A Bulks List. It is not on the Bulks List, was not among the peptides reviewed in July 2026, and is not on the February 2027 docket. Ipamorelin products were named in FDA’s August 2026 warning letters to online sellers. Prohibited in sport by WADA as a growth hormone secretagogue.
https://pubmed.ncbi.nlm.nih.gov/9849822/
https://pubmed.ncbi.nlm.nih.gov/10373343/
https://pubmed.ncbi.nlm.nih.gov/9467542/
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