If you've been researching growth hormone peptides for more than about twenty minutes, you've probably encountered the Ipamorelin + CJC-1295 stack. It's the most prescribed GH peptide protocol at hormone optimisation clinics, the most discussed GH stack in research communities, and the starting point most practitioners reach for when patients want GH support without the regulatory and physiological complexity of exogenous HGH.
Most of the guides you'll find online are either dosing calculators with no mechanistic context, or clinic advertorials that skip the evidence quality discussion entirely. This guide covers the mechanism properly, explains the DAC vs no-DAC distinction that most sources handle poorly, and gives an honest assessment of what the evidence actually supports, including where the gaps are.
Why these two compounds specifically
Growth hormone release from the pituitary gland is regulated by two opposing hormonal signals. GHRH (growth hormone releasing hormone) stimulates GH release. Somatostatin inhibits it. The natural result is pulsatile GH secretion, episodic bursts, primarily overnight, that decline significantly with age.
Ipamorelin and CJC-1295 activate two completely separate receptor systems that both converge on stimulating GH release, but through distinct pathways.
The result of combining them is a GH pulse that is meaningfully larger than either compound produces alone, often described as synergistic rather than merely additive. The 1991 Bowers et al. research demonstrated this dual-receptor effect, and it's the foundational pharmacology that justifies the combination over using either compound individually.
The selectivity of ipamorelin is also worth emphasising. Earlier GHRPs (GHRP-2, GHRP-6) produced GH release but also raised cortisol and prolactin in a dose-dependent fashion. Ipamorelin was specifically developed to achieve the GH stimulation without the cortisol and prolactin effects, a meaningful improvement in the selectivity profile that makes it more practical for longer-term use.
The DAC distinction, the most important thing to get right
The single most consequential detail in this stack, and the one most frequently handled incorrectly, is the distinction between CJC-1295 with DAC and CJC-1295 without DAC. These are not interchangeable compounds and their protocols are completely different.
CJC-1295 without DAC (also sold as Modified GRF 1-29 or Mod GRF 1-29) has a half-life of approximately 30 minutes. It produces a discrete GH pulse when injected, consistent with the body's natural pulsatile GH secretion pattern. Its short half-life matches ipamorelin's approximately 2-hour half-life well, making them suitable for co-injection.
CJC-1295 with DAC has a half-life of 6 to 8 days. The Drug Affinity Complex binds the peptide to albumin in the blood, dramatically extending its circulation time. A single weekly injection produces a sustained, non-pulsatile elevation in GH and IGF-1 over the following week. This is a fundamentally different pharmacokinetic profile, continuous GH elevation rather than discrete pulses.
CJC-1295 with DAC requires 1–2mg once weekly. CJC-1295 without DAC requires 100–200 mcg two to three times daily. Applying a daily-dose protocol to the DAC version can cause sustained supra-physiological GH elevation. Always confirm which version you have before dosing. If your supplier's label is ambiguous, contact them for clarification, the two products are not equivalent.
For the Ipamorelin stack, CJC-1295 without DAC is the appropriate choice. The DAC version's extended half-life produces a different and less physiologically appropriate GH pattern for most goals, and pairs poorly with ipamorelin's short-acting pulse mechanism.
The evidence base, honest assessment
The ipamorelin + CJC-1295 combination, as a specific stack, does not have its own clinical trial data. What exists is pharmacology research on each compound individually, plus mechanistic studies on GHRH + GHRP co-administration. The clinical outcomes data, body composition, recovery, sleep quality, anti-aging effects, comes primarily from extrapolation from related compounds, particularly tesamorelin.
Tesamorelin is the only FDA-approved compound in the GHRH analogue class, approved for HIV-associated lipodystrophy. Its clinical trial data shows approximately 18% reduction in visceral adipose tissue, improvements in lean body mass, and, notably, a randomised controlled trial demonstrating significant cognitive benefits in adults with mild cognitive impairment. These outcomes come from the same mechanism the Ipamorelin + CJC-1295 stack is designed to activate.
Ipamorelin has controlled trial data confirming selective GH release without cortisol or prolactin elevation. CJC-1295 has clinical data showing sustained GH and IGF-1 elevation. The combination as a stack has no dedicated randomised controlled trials. Efficacy for body composition, recovery, and anti-aging outcomes is extrapolated from tesamorelin's trials and from GHRH + GHRP co-administration research. This is a reasonable scientific inference, the mechanisms align, but it is extrapolation, not direct evidence.
Dosing protocols
The pre-bed timing for the primary dose is not arbitrary. The body's largest natural GH pulse occurs in the first hours of slow-wave sleep. Ipamorelin + CJC-1295 taken before bed amplifies this pulse, working with the body's existing circadian GH rhythm rather than imposing an unnatural secretion pattern. Empty stomach administration matters because insulin elevation suppresses GH release, eating before injecting blunts the GH pulse.
The 5-days-on / 2-days-off schedule and the 8-week cycle breaks are designed to maintain pituitary sensitivity. Continuous uninterrupted stimulation risks downregulation of the receptors, reducing effectiveness over time. Cycle breaks allow receptor sensitivity to recover.
CJC-1295 with DAC, when it makes sense
The DAC version isn't inherently inferior, it's appropriate for different goals. If the primary objective is sustained IGF-1 elevation rather than discrete pulsatile GH release, once-weekly CJC-1295 with DAC (1–2mg) produces a more consistent hormonal environment. Some protocols use the DAC version for its convenience, one injection per week rather than daily, accepting the different pharmacokinetic profile as a reasonable trade-off.
When using CJC-1295 with DAC, it is typically not co-administered with ipamorelin in the same injection. Instead, the DAC version is injected once weekly and ipamorelin is used separately for its additional GH pulse effects. This is a more advanced protocol and the interaction between sustained GHRH agonism and pulsatile GHRP stimulation is less well characterised.
| Factor | CJC-1295 no DAC | CJC-1295 with DAC |
|---|---|---|
| Half-life | ~30 minutes | 6–8 days |
| GH pattern | Pulsatile, mimics natural rhythm | Sustained, non-pulsatile |
| Dose | 100–200 mcg, 2–3x daily | 1–2mg once weekly |
| Stack with ipamorelin | Co-inject, half-lives match | Separate administration |
| Injection frequency | Daily | Once weekly |
| Best for | Pulsatile GH, recovery, sleep, anti-aging | Sustained IGF-1 elevation |
What to realistically expect
Onset of noticeable effects varies by individual and by outcome measured. The most consistently reported early effect, within the first one to two weeks, is improved sleep quality. Specifically, deeper sleep with more vivid dreams, and improved subjective recovery from training. This is consistent with the known role of GH in slow-wave sleep architecture.
Body composition changes take longer and are more modest than the community discussion sometimes suggests. Over an 8–12 week cycle, lean mass changes on the order of 1–2kg and modest visceral fat reduction are consistent with what the mechanism would predict and what extrapolated tesamorelin data shows. These are real but not dramatic outcomes. The compounds do not produce the body composition changes associated with exogenous HGH at supraphysiological doses, they work through the body's own regulatory system rather than overriding it, which is both their safety advantage and their limitation.
Skin quality, hair thickness, and recovery speed are the other commonly reported outcomes. These are harder to quantify and the placebo contribution is difficult to isolate, but they align mechanistically with GH's known effects on protein synthesis and cellular repair.
Safety considerations and who should not use this stack
The GH secretagogue stack is generally considered to have a more favourable safety profile than exogenous HGH because it operates through the body's own feedback mechanisms. If GH levels rise too high, somatostatin increases to suppress further release, a regulatory brake that doesn't exist with exogenous HGH administration.
That said, meaningful contraindications exist. Anyone with active or prior cancer should not use compounds that elevate GH and IGF-1, growth hormone has documented mitogenic effects and in theory could support tumour growth. People with diabetes or insulin resistance need to exercise particular caution: GH is counter-regulatory to insulin and can worsen glycaemic control. Untreated pituitary tumours, serious cardiovascular disease, and pregnancy are additional contraindications.
Athletes subject to WADA testing should note that both ipamorelin and CJC-1295 are on the prohibited list. Detection windows vary and can extend beyond the active half-life of the compounds.
If the goals are visceral fat reduction and body composition improvement specifically, Tesamorelin is the FDA-approved GHRH analogue with the strongest human clinical dataset in this class, including an RCT showing cognitive benefits. It works through the same mechanism as CJC-1295. For people who can access it through a physician, it represents a supervised, quality-verified, evidence-backed route to the same biological target.