CJC-1295 + IpamorelinWhat the studies show
Two peptides for two receptors on the same pituitary cell. The idea comes from a 1990 study in men; the pair itself has never been tested together.
5 min read · Mixed evidence · Updated November 2026
In short
- Name
- CJC-1295 (no DAC) + ipamorelin (sold by Progression Labs as CJC-1295 + Ipamorelin)
- Evidence
- Mixed evidence
- Bottom line
- Two mechanisms, each with a small human literature of its own, and one 1990 single-dose study showing GHRP-plus-GHRH synergy with different molecules; there is no published study of CJC-1295 and ipamorelin given together.
Before you read this
This guide explains what published studies found. That is all it is.
It is not medical advice and it is not instructions for using anything. Where a dose appears, we are reporting what a named study gave the people or animals in it — a fact about the study, not an instruction to you.
The compounds here are not approved by the FDA for use in people and are sold for laboratory research only. A study tells you what happened to the subjects in it; it does not tell you what would happen to you. Talk to a doctor first.
What it is
This is two peptides, not one. Modified GRF 1-29, known under the CJC-1295 name but without the albumin-binding DAC tail, is a stabilised copy of the first 29 amino acids of growth hormone releasing hormone (GHRH). Ipamorelin is a five-amino-acid mimic of ghrelin 1. The two act on different receptors on the same growth-hormone-making cells in the pituitary, and the reason anyone pairs them is a finding from 1990: in healthy men, a ghrelin-type peptide and GHRH given together released more growth hormone than the sum of what each released alone 2. That finding was made with other molecules. The combination described here has no published study of its own, so this guide lays out the evidence for each half and then says where the gap is.
The studies below call this molecule CJC-1295 (no DAC) + ipamorelin. Progression Labs sells it as CJC-1295 + Ipamorelin; the guide uses the store's name and the papers use theirs.
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Two receptors, one cell
GHRH is the hypothalamus's own signal to the pituitary. It binds the GHRH receptor on somatotroph cells, raises cyclic AMP inside them, and drives both the making and the release of growth hormone. The ghrelin receptor is a separate protein on the same cells, cloned in 1996 by a Merck group using GHRP-6 as the bait, and found in the hypothalamus as well as the pituitary 3. Its natural ligand, ghrelin, was identified in the stomach three years later 4. Activating it releases growth hormone through a different internal pathway, built on calcium rather than cyclic AMP, and in the hypothalamus it also nudges the system toward releasing more GHRH and less of the brake hormone, somatostatin 34.
That is the logic of pairing: one peptide pushes the cell directly, the other pushes it through a second door and loosens the brake, and the two signals do not simply add.
What the synergy study found
Bowers and colleagues reported it in the Journal of Clinical Endocrinology & Metabolism in 1990. Healthy men received GHRP-6 by vein, GHRH by vein, or both; the growth hormone peak after the pair was larger than the two single responses added together, which is the definition of synergy rather than a mere sum 2. This is a single-dose, intravenous study with GHRP-6 and native GHRH. It was not done with ipamorelin, not done with modified GRF 1-29, and not done under the skin or over repeated days.
What each half has shown alone
Ipamorelin was introduced in 1998 as a GHRP that released growth hormone in rat pituitary cells and in pigs with potency like GHRP-6 but, unlike GHRP-6 and GHRP-2, without raising ACTH or cortisol in the pigs 1. Its human record is a volunteer pharmacokinetic study and one 114-patient placebo-controlled surgical trial that missed its endpoint; there is no human study of it for body composition.
The GHRH half has human data only in its long-acting form. CJC-1295 with DAC, in healthy adults, raised mean growth hormone 2- to 10-fold and IGF-1 1.5- to 3-fold after a single injection, with a half-life of 5.8 to 8.1 days 5, and the pituitary kept its normal pulses while it did so 6. The no-DAC version used in this pair shares the receptor and the base sequence but lasts minutes rather than days, and has no human study at all.
What is not known
No published study, in people or in animals, has given modified GRF 1-29 and ipamorelin together. Whether the 1990 synergy holds for these two molecules, by this route, with repeated use, is an inference, and the size of any combined effect in a person has never been measured. Neither peptide is an approved drug anywhere, and there is no safety record for the pair.
What these studies are, and aren't
Mixed evidence. Two mechanisms, each with a small human literature of its own, and one 1990 single-dose study showing GHRP-plus-GHRH synergy with different molecules; there is no published study of CJC-1295 and ipamorelin given together.
Sources
- 1Raun K et al. Ipamorelin, the first selective growth hormone secretagogue. European Journal of Endocrinology, 1998.
- 2Bowers CY et al. Growth hormone (GH)-releasing peptide stimulates GH release in normal men and acts synergistically with GH-releasing hormone. Journal of Clinical Endocrinology & Metabolism, 1990.
- 3Howard AD et al. A receptor in pituitary and hypothalamus that functions in growth hormone release. Science, 1996.
- 4Kojima M et al. Ghrelin is a growth-hormone-releasing acylated peptide from stomach. Nature, 1999.
- 5Teichman SL et al. Prolonged stimulation of growth hormone (GH) and insulin-like growth factor I secretion by CJC-1295, a long-acting analog of GH-releasing hormone, in healthy adults. Journal of Clinical Endocrinology & Metabolism, 2006.
- 6Ionescu M, Frohman LA. Pulsatile secretion of growth hormone (GH) persists during continuous stimulation by CJC-1295, a long-acting GH-releasing hormone analog. Journal of Clinical Endocrinology & Metabolism, 2006.
More in Growth hormone axis
- CJC-1295 (no DAC): What the Studies ShowSermorelin with four amino acids swapped to survive the blood longer, and without the albumin-binding tail that gave the DAC version its week-long half-life.
- CJC-1295 with DAC: What the Studies ShowA GHRH analogue that bonds to albumin in the blood: one injection raised growth hormone for about a week in healthy adults, with the normal pulses intact.
- GHRP-2: What the Studies ShowThe potent GHRP approved in Japan as a one-dose test for growth hormone deficiency, and shown to make healthy men eat about a third more at a single meal.
- GHRP-6: What the Studies ShowThe 1984 hexapeptide that came before its own receptor and before ghrelin — and the reason the hunger it causes is the receptor doing its job.
- Hexarelin: What the Studies ShowGHRP-6 with one methyl group added, active by mouth and nose as well as by injection, and the GHRP whose growth hormone response was shown to fade by 16 weeks.