Two compounds frequently sold together as a "GH stack". They are mechanistically distinct — and most clinical literature treats them as complementary rather than competing.
Modified GRF (1-29) · CJC-1295 DAC
NNC 26-0161
Both stimulate GH release — but via independent mechanisms that combine synergistically.
CJC-1295 is a GHRH analogue: it binds GHRH receptors on pituitary somatotrophs and amplifies the body's natural GHRH-driven GH pulse. Ipamorelin is a ghrelin-receptor agonist: it generates a separate GH pulse through a different pathway. Combining the two produces summation — higher GH amplitude than either compound alone.
This is the basis of the standard "Ipa + Mod GRF" stack. Most clinical and grey-market literature pairs them rather than positions them in opposition.
Two GH pathways, summed.
| CJC-1295 | Ipamorelin | |
|---|---|---|
| Receptor target | GHRH receptor (somatotrophs) | Ghrelin receptor (GHS-R1a) |
| Pulse style | Amplifies endogenous GH pulse | Generates independent GH pulse |
| Cortisol effect | None expected | None — selective by design |
| Prolactin effect | None expected | None — selective by design |
| Combined use | Synergistic with ghrelin agonists | Synergistic with GHRH analogues |
Both produce GH/IGF-1 elevation; combined use produces larger amplitude than either alone.
CJC-1295 with DAC produces sustained 1.5–3x baseline IGF-1 elevation over 7–14 days following a single dose, in phase-1 data. Modified GRF (1-29) produces shorter, sharper pulses.
Ipamorelin produces dose-dependent GH peaks of 30–55 ng/mL within 30 minutes of subcutaneous administration. The selective profile means no concomitant cortisol or prolactin elevation — a meaningful advantage over earlier GHRPs.
Combined use stacks the two pathways. Most GH-axis literature treats the combination as the practical use-case; standalone use of either compound is less common in published protocols.
Both are well-tolerated acutely; supply quality is the dominant practical concern for both.
| Effect | CJC-1295 | Ipamorelin |
|---|---|---|
| Injection-site reaction | 20–30% | 15–25% |
| Flushing / warmth | 10–15% | 5–10% |
| Mild hunger (acute) | Minimal | ~5% |
| Cortisol elevation | Not expected | Not observed |
| Prolactin elevation | Not expected | Not observed |
| Long-term safety data | Limited | Limited |
Both unlicensed; both supply via research-chemical channels.
Neither compound has UK marketing authorisation. Both are sold via research-chemical channels with no regulatory quality assurance. Independent product testing across vendors has documented identity failures, contamination, and incorrect peptide content for both compounds.
Supply for human use without prescription is illegal under the Human Medicines Regulations 2012. There is no meaningful difference in legal status between the two.
Most published GH-axis literature treats CJC-1295 and Ipamorelin as complementary components rather than competing options. The two compounds work through independent receptor pathways and produce summated GH amplitude when used together — that's why "Ipa + Mod GRF" is the dominant practical protocol.
If forced to pick one, the answer depends on what you're prioritising. Ipamorelin alone has the cleaner side-effect profile and shorter dosing intervals. CJC-1295 with DAC offers weekly dosing and more sustained IGF-1 elevation. But the strongest position in the available literature is the stacked use — neither compound is positioned as a standalone primary therapy in published trial protocols.
You want sustained IGF-1 elevation with weekly dosing convenience, and the longer half-life of the DAC variant suits your protocol. Mod GRF (1-29) suits closer-to-physiological pulse mimicry.
You're prioritising the cleanest side-effect profile and want flexible per-pulse dosing. Standalone Ipa is occasionally used as an entry-level GHRP before adding a GHRH analogue.
This verdict reflects the published evidence as of 14 April 2026. We update comparison pages whenever new phase-3 data is published.