Search behaviour treats this as a versus question. The pharmacology does not. Ipamorelin and CJC-1295 bind two different receptors on the same pituitary cell, and that separation is the whole reason they are sold together as a blend. Framing them as rivals gets the biology backwards: they are different halves of one axis. This page is educational and makes no recommendation about using either compound.
The short answer
Ipamorelin is a synthetic pentapeptide that activates the ghrelin receptor (GHS-R1a) and produces a single growth hormone pulse lasting hours. CJC-1295 is a modified fragment of growth hormone–releasing hormone that acts at the GHRH receptor; in its albumin-binding "DAC" form it stays in circulation for the better part of a week. Both work by persuading the pituitary to release the body's own growth hormone rather than supplying growth hormone from outside, so both are capped by whatever that gland can still secrete.
The comparison people usually want — which produces better results — has no answer, because neither compound has been tested against a body-composition, recovery, or sleep endpoint in humans, and the two have never been compared head to head. What can be compared is pharmacology, development history, and regulatory record, and there the differences are sharp.
Head-to-head
| Dimension | Ipamorelin | CJC-1295 |
|---|---|---|
| Receptor target | Growth hormone secretagogue receptor GHS-R1a — the ghrelin receptor. | The GHRH receptor on anterior-pituitary somatotrophs. |
| Molecule and mechanism | Synthetic pentapeptide (Aib-His-D-2-Nal-D-Phe-Lys-NH2). Mimics ghrelin's action on the pituitary to trigger a discrete pulse of the body's own growth hormone. | Tetra-substituted analog of human GRF(1-29) — the shortest fully active fragment of GHRH. Substitutions resist enzymatic breakdown; the DAC version adds a maleimide group that binds covalently to Cys34 of circulating albumin. |
| Half-life | Terminal half-life about 2 hours in humans, GH peaking near 40 minutes, IV route (Gobburu 1999). | With DAC: 5.8–8.1 days (Teichman 2006). Without DAC: never measured in a published human study. |
| Selectivity / hormone spillover | No ACTH or cortisol release beyond what GHRH itself produced, even above 200× the ED50 for GH; no change in FSH, LH, prolactin or TSH — in rats and swine (Raun 1998). | Narrow by construction — a GHRH analog acts where GHRH acts. No published multi-hormone panel comparable to ipamorelin's exists. |
| Clinical development history | Novo Nordisk origin; Helsinn Therapeutics ran a phase 2 trial in postoperative ileus that missed its primary endpoint (Beck 2014). A 320-patient follow-up (NCT01280344) completed in 2014 and posted nothing. | ConjuChem characterized the DAC form in healthy adults, then withdrew it from clinical trials in 2006 after the death of a subject in a phase 2 study (FDA briefing, December 2024). No phase 3, no publication of that trial. |
| Regulatory status | No approved indication anywhere. FDA's Pharmacy Compounding Advisory Committee voted 0 yes / 12 no / 1 abstain against the 503A bulks list on 29 October 2024, free base and acetate alike (minutes). | No approved indication anywhere. Same committee, 4 December 2024: 0 yes / 13 no for CJC-1295 free base and for all three DAC forms; 1 yes / 12 no for CJC-1295 acetate (minutes). |
| Anti-doping | Prohibited at all times under WADA section S2, among growth hormone secretagogues (Prohibited List). | Prohibited at all times under WADA section S2, among GHRH analogues. Relabelling a vial "modified GRF (1-29)" changes nothing. |
Two receptors, one output
Both peptides end at the same place: the somatotroph cells of the anterior pituitary, releasing growth hormone. They arrive by different doors. Ipamorelin was characterized as an agonist at the growth hormone secretagogue receptor, GHS-R1a — the receptor ghrelin uses (Raun et al., Eur J Endocrinol 1998). CJC-1295 was identified as a long-lasting GRF analog that activates the GRF (GHRH) receptor on the rat anterior pituitary (Jetté et al., Endocrinology 2005).
That shared dependency on a working pituitary is the constraint both share. It is also why neither is useful in complete growth hormone deficiency, and why comparisons with recombinant growth hormone — which bypasses the gland entirely — do not transfer.
"CJC-1295" names two very different molecules
The single biggest source of confusion in this comparison is that the name on the vial does not identify the drug. FDA evaluated five chemically distinct CJC-1295-related bulk substances — free base, acetate, DAC free base, DAC acetate, DAC trifluoroacetate — and concluded that even in the published human studies it is unclear which substance was used (FDA briefing document, PCAC December 2024).
The forms are not close. In the DAC version, a maleimide group reacts with the free thiol on Cys34 of serum albumin after injection, so the peptide circulates attached to albumin; in rats it remained in plasma beyond 72 hours and produced roughly a four-fold larger GH area under the curve than native hGRF(1-29) (Jetté 2005). In healthy adults aged 21–61, a single subcutaneous dose raised mean plasma GH 2- to 10-fold for six days or more and IGF-1 1.5- to 3-fold for 9–11 days, with a half-life of 5.8–8.1 days; with repeated dosing IGF-1 stayed above baseline as long as 28 days (Teichman et al., J Clin Endocrinol Metab 2006).
CJC-1295 without DAC — usually sold as "modified GRF (1-29)" — has no albumin anchor and no published human pharmacokinetic study at all. So "ipamorelin vs CJC-1295" is either a two-hour pulse against a week-long elevation, or a two-hour pulse against an unmeasured short-acting peptide, depending entirely on which vial is in hand.
What ipamorelin's "selectivity" actually claims
Ipamorelin's headline property is the narrowness of its hormonal footprint. In the original characterization it released GH from primary rat pituitary cells with potency close to GHRP-6 (EC50 1.3 ± 0.4 vs 2.2 ± 0.3 nmol/L, Emax 85% vs 100%), while producing no ACTH or cortisol response significantly different from GHRH stimulation — even at doses more than 200-fold above the ED50 for GH release — and no change in FSH, LH, prolactin or TSH (Raun 1998).
Read precisely, that is a claim about hormonal side effects in animals. It is not a claim that ipamorelin releases more GH, and not a claim of any clinical benefit. It also does not separate ipamorelin from CJC-1295, which as a GHRH analog is narrow by construction — it separates ipamorelin from GHRP-2 and GHRP-6, the secretagogues more prone to moving cortisol and prolactin.
Why they are sold together — and what the synergy data shows
The mechanistic rationale for pairing a GHRH analog with a ghrelin-receptor agonist is real, and it has human evidence behind it. In older adults, continuous subcutaneous infusion of GHRP-2 combined with GHRH drove GH secretion beyond GHRH alone over 24 hours, and over 30 days of continuous delivery the GHRP-2/GHRH combination stimulated GH more than either GHRP-2 (P = 0.021) or GHRH (P = 0.012) on its own (Bowers et al., J Clin Endocrinol Metab 2004).
That study is the load-bearing citation under every blend on the market, and it is worth noticing what it is not. It used GHRP-2, not ipamorelin. It used GHRH, not CJC-1295. It used continuous infusion, not intermittent injections. The combination of ipamorelin and CJC-1295 has never been tested in a controlled human trial, and no such trial is registered — a gap covered in more detail on the CJC-1295 + ipamorelin page. A further mismatch hides inside the "1:1 blend" framing: pairing the DAC form with daily ipamorelin combines a multi-day continuous GHRH signal with a short pulse, which is not what the infusion study modelled either.
How both programs ended
Most gray-market peptides never had a sponsor or a registered trial. These two did, and both programs stopped — for entirely different reasons.
- Ipamorelin failed on efficacy. In a randomized, placebo-controlled phase 2 study in bowel-resection patients (117 enrolled, 114 analyzed), median time from first dose to tolerating a standardized solid meal was 25.3 hours on ipamorelin versus 32.6 on placebo, p = 0.15, with no significant differences in the key or secondary efficacy analyses either (Beck et al., Int J Colorectal Dis 2014). The dose-finding study that followed enrolled 320 patients, completed in May 2014, and has posted no results and produced no publication (NCT01280344).
- CJC-1295 stopped after a death. FDA's review states that "ConjuChem Biotechnology withdrew CJC-1295 DAC from clinical trials in 2006 after the death of a subject involved in a phase 2 trial" (FDA, December 2024). The trial data were never published, so causality was never resolved and now cannot be.
A negative trial and an unresolved fatality are different kinds of problem, and neither is the kind of history that supports the claims attached to these peptides in wellness marketing.
Regulatory status and sport
Neither peptide has an approved indication anywhere. Both were nominated for FDA's 503A bulks list, which governs what compounding pharmacies may legally use, and both were rejected by the Pharmacy Compounding Advisory Committee in 2024. On 29 October the committee voted 0 in favour, 12 against, 1 abstaining on ipamorelin free base and identically on ipamorelin acetate, agreeing that the available data showed a lack of information supporting safety and efficacy (PCAC minutes). On 4 December the votes on CJC-1295 free base and on all three DAC forms were 0 to 13, with CJC-1295 acetate at 1 to 12 (PCAC minutes).
In sport the position is simpler still: both are prohibited at all times under section S2 of the WADA Prohibited List, ipamorelin among growth hormone secretagogues and CJC-1295 among GHRH analogues. Because the list also covers substances of similar structure or biological effect, alternative product names offer no protection.
What this comparison cannot settle
No trial has compared ipamorelin with CJC-1295 in humans, and no trial has tested either against the outcomes they are marketed for. What exists is one negative clinical trial, one pharmacokinetic study, one terminated program, a set of animal characterizations, and a synergy result belonging to two other molecules. Anyone weighing these compounds is weighing pharmacology against an absence of clinical evidence — not one product against another.
Where to go deeper
- Ipamorelin overview · benefits · side effects · dosing concepts · research
- CJC-1295 with DAC · side effects · research
- CJC-1295 without DAC (modified GRF 1-29) · dosing concepts
- CJC-1295 + Ipamorelin (the blend) · research
- CJC-1295 vs sermorelin — the same GHRH backbone, one of which once held an approval.
- What are the risks of peptides? · Why do some doctors not prescribe peptides? · What are the downsides to peptides?