# Ipamorelin: The Selective Growth Hormone Secretagogue, and the Stacks It's Studied In > Ipamorelin is a selective growth hormone secretagogue most often studied alongside GHRH analogs such as CJC-1295. A cited, plain-English digest of the monotherapy data and the combination rationale. A peer-reviewed digest of what the peptide does on its own, why researchers pair it with GHRH analogs like CJC-1295, and where the human evidence actually stops. Every number is cited. ## Start here Ipamorelin is a small lab-made peptide — a chain of just five amino acids — that tells the pituitary gland to release a pulse of growth hormone (GH), the body's own signal for growth and repair. What makes it stand out is precision: it nudges GH up without raising the stress hormone cortisol or the milk hormone prolactin, the off-target effects that dogged older peptides in its family [1]. People in research-use communities reach for it hoping for deeper sleep, faster recovery, and a slow shift toward a leaner body. The honest catch: almost all of the solid data is in rats, pigs, and a handful of short human studies. The one real clinical trial in people — for slow bowel recovery after surgery — did not work [3]. You will rarely see ipamorelin discussed by itself; it is usually paired with a longer-acting partner called CJC-1295, because the two hit the GH switch through different doors. This site sorts the single-peptide findings from the combination claims, and lays out what people report — including the downsides — on [the effects page](/effects). ## What the ipamorelin literature actually shows Ipamorelin (sequence Aib-His-D-2-Nal-D-Phe-Lys-NH2) was characterized in 1998 as the first highly GH-selective growth hormone secretagogue. In rat pituitary cells, anaesthetised rats, and conscious swine, it released GH as potently as the older peptide GHRP-6 (swine ED50 2.3 nmol/kg versus 3.9 nmol/kg for GHRP-6) — yet it did not raise ACTH or cortisol above baseline even at doses more than 200-fold above its GH threshold [1]. That selectivity is the whole reason the molecule is interesting: it is a clean GH lever. The human record is thin and, where it exists, sobering. A 1999 pharmacokinetic study in healthy men gave single intravenous infusions and measured a terminal half-life of roughly 2 hours, with the GH response arriving as one discrete pulse about 40 minutes after dosing [2]. The only published Phase 2 trial — 114 adults given ipamorelin after bowel surgery to speed gut recovery — missed its primary endpoint outright (time to first tolerated meal 25.3 hours versus 32.6 hours on placebo, p=0.15) [3]. That is the defining human result: efficacy was tested, and it was not shown. ## Why it is almost never studied alone Ipamorelin works on one receptor — GHS-R1a, the ghrelin or "hunger-hormone" receptor — which is a different door into GH release than the one used by growth-hormone-releasing hormone (GHRH). That is the mechanistic basis for the most common research pairing: a short, pulsing peptide like ipamorelin alongside a long-acting GHRH analog such as CJC-1295. The two pathways are complementary, so combining them is meant to produce a larger, more sustained GH signal than either alone [1]. The evidence for the partner is real but separate. A single subcutaneous dose of CJC-1295 in healthy adults produced 2- to 10-fold GH increases for six-plus days and 1.5- to 3-fold sustained IGF-1 elevation, while preserving the body's natural pulsing rhythm [7][8]. That study was on CJC-1295, not ipamorelin — a distinction this site keeps strict throughout. The combination itself has never been tested in a controlled trial for any outcome; the [ipamorelin cjc-1295](/with-cjc-1295) rationale rests on two separate single-agent pharmacology stories stitched together. ## What it is — and what it is not Ipamorelin is a research peptide. It has never been approved as a drug by the FDA, the EMA, or any other regulator, anywhere [11]. Its only clinical program (postoperative ileus) reached Phase 2 and stopped after the trial failed [3]. In 2024 the FDA removed ipamorelin acetate from Category 2 of the interim Section 503A bulk-substances list and reviewed it at the October 29, 2024 Pharmacy Compounding Advisory Committee meeting, tightening compounding-pharmacy access [11]. It is also banned in sport at all times under the World Anti-Doping Agency's category S2, and is detectable in urine [16][17]. None of that is the same as "dangerous" or "useless" — it means the molecule lives almost entirely in the preclinical and gray-market world, and the marketing for anti-aging, fat loss, and muscle far outruns the controlled evidence. What follows is a digest of that evidence: the [Ipamorelin research](/research) in detail, the doses studied, and what people report. We summarize the published science; we do not sell anything and we give no medical advice. --- An editorial digest of the ipamorelin literature and the GHRH-analog stacks it is studied beside — single-peptide findings kept apart from combination claims, and nothing here dosed, compounded, prescribed, or sold.