Side-by-side comparison
| Property | CJC-1295 | Ipamorelin |
|---|---|---|
| Class | GHRH analogue | GHRP / selective ghrelin (GHSR-1a) agonist |
| What it does | Raises GH released per pulse (amplitude) | Initiates the GH pulse; suppresses somatostatin |
| Approximate half-life | ~6–8 days (with DAC) · ~30 min (no DAC) | ~2 hours |
| Typical dosing frequency | 1–2×/week (DAC) · 2–3×/day (no DAC) | 2–3×/day (often before bed) |
| Effect on cortisol / prolactin | Not a primary concern (GHRH pathway) | Selective — no meaningful cortisol/prolactin rise |
| IGF-1 effect window | Up to ~14 days per dose (DAC) | ~12–24 hours per pulse |
| Approval status | Not approved — research chemical | Not approved — research chemical |
| Data quality | Human PK study (with DAC) | Mostly animal PK |
See the source-level profiles for CJC-1295 with DAC, CJC-1295 without DAC (Mod GRF 1-29), and ipamorelin — or plot all three decay curves together with the free half-life calculator.
Mechanism: two levers, one axis
Growth hormone release is governed by a push-pull system. GHRH (a releasing hormone) tells the pituitary to secrete GH; somatostatin tells it to stop; and ghrelin amplifies the pulse. CJC-1295 and ipamorelin each grab a different lever.
CJC-1295 — the GHRH lever
CJC-1295 is a modified analogue of GHRH. It binds the GHRH receptor on pituitary somatotrophs and increases the size of each GH release. It does not, by itself, create new pulses — it makes the pulses your body already generates bigger and raises baseline IGF-1.
Ipamorelin — the ghrelin lever
Ipamorelin is a growth-hormone-releasing peptide that selectively activates the ghrelin receptor (GHSR-1a). That does two things: it initiates a GH pulse and it blunts somatostatin, the brake. Unlike older GHRPs (GHRP-6, GHRP-2, hexarelin), it is clean — it does not meaningfully raise cortisol, prolactin, or ACTH, and it does not trigger the intense hunger associated with GHRP-6.
Half-life and pharmacokinetics
This is where the two diverge most, and where the "vs" question gets interesting. There are effectively three different pharmacokinetic profiles here, because CJC-1295 exists in two forms.
- CJC-1295 with DAC: the Drug Affinity Complex binds the peptide covalently to albumin, stretching the half-life to ~6–8 days and allowing once- or twice-weekly dosing.
- CJC-1295 without DAC (Mod GRF 1-29): no albumin anchor, so it clears in ~30 minutes and is dosed 2–3× daily to mimic natural pulsatility.
- Ipamorelin: ~2-hour half-life; the GH pulse it triggers lasts roughly 3–4 hours, with downstream IGF-1 effects over ~12–24 hours.
You can see exactly why one is dosed weekly and the other multiple times a day by overlaying the curves in the half-life calculator, then planning the combination in the peptide stack planner.
Why they are stacked instead of chosen
Because CJC-1295 raises pulse amplitude and ipamorelin initiates the pulse, combining a GHRH analogue with a ghrelin agonist produces a larger, more synergistic GH response than either compound alone — the two mechanisms multiply rather than overlap. That synergy is the entire rationale behind the ubiquitous "CJC-1295 + ipamorelin" protocol. Framed correctly, the question is rarely "which one" — it is "which CJC-1295 form, at what timing, alongside ipamorelin."
Side effects and selectivity
Reported effects for both are generally mild in the limited data available — transient injection-site redness, flushing, occasional water retention or tingling, most common in the first week or two. Ipamorelin's defining feature is selectivity: it raises GH without the cortisol and prolactin elevation seen with non-selective GHRPs, which is the main reason it displaced GHRP-6 in modern protocols. The open question for CJC-1295 is chronic GHRH-receptor downregulation, for which long-term human safety data does not exist.
Timing and dosing logic
The pharmacokinetics dictate the schedule. Short-acting compounds (no-DAC CJC-1295, ipamorelin) are typically dosed before bed, at least two hours after eating, to align with the body's largest natural nocturnal GH pulse and avoid the GH-blunting effect of elevated insulin. DAC CJC-1295 is dosed on a fixed weekly day because its long half-life carries it across the interval. Doses should never be combined in one syringe without guidance, and any protocol belongs with a qualified clinician. For mixing and dose math, see the reconstitution calculator.
How they compare to sermorelin and tesamorelin
CJC-1295 sits in the same GHRH-analogue family as sermorelin and tesamorelin — sermorelin is shorter-acting, and tesamorelin is the one FDA-approved GHRH analogue (for HIV-associated lipodystrophy). Ipamorelin has no approved counterpart. The full half-life reference for all 44 tracked compounds lives in the compound database.
Frequently asked questions
What is the difference between CJC-1295 and ipamorelin?
CJC-1295 is a GHRH analogue that raises how much GH is released per pulse; ipamorelin is a selective ghrelin-receptor agonist that triggers the pulse. Different receptors, complementary effects.
Which has a longer half-life?
CJC-1295 with DAC (~6–8 days) is by far the longest. Ipamorelin is ~2 hours. CJC-1295 without DAC (~30 minutes) is actually shorter-acting than ipamorelin.
Which is better, CJC-1295 or ipamorelin?
Neither — they do different jobs and are almost always used together rather than chosen against each other.
Can you take CJC-1295 and ipamorelin together?
Yes; the combination is the standard protocol because the two mechanisms are synergistic. Neither is FDA-approved, so use should be clinician-directed.
Does ipamorelin raise cortisol or prolactin?
No — at typical doses it is selective for GH and does not meaningfully raise cortisol, prolactin, or ACTH, unlike older GHRPs.