GHRP-2 vs GHRP-6 vs Ipamorelin
GHRP-2 vs GHRP-6 vs Ipamorelin — cortisol, prolactin, appetite, GH amplitude, and why Ipamorelin became the default for clean GH pulses.
Updated May 7, 2026 · 5 min read
The GHRP class — ghrelin mimetics that trigger GH release through the GHS-R1a receptor — has three main injectable members: GHRP-2, GHRP-6, and Ipamorelin. They all work through the same receptor, but the off-target profile is what separates them. The choice of GHRP is mostly a choice about which side effects you're willing to live with.
Quick comparison
| Property | GHRP-2 | GHRP-6 | Ipamorelin |
|---|---|---|---|
| GH pulse amplitude | Highest | High | Moderate |
| Cortisol elevation | Notable | Notable | Minimal |
| Prolactin elevation | Moderate | Moderate | Minimal |
| Appetite stimulation | Moderate | Strong (defining feature) | Minimal |
| Selectivity | Low | Low | High |
| Half-life | About 15–30 min | About 15–30 min | About 2 hours |
| Typical dose | 100–300 mcg | 100–300 mcg | 100–300 mcg |
| Cadence | 2–3x daily | 2–3x daily | 1–3x daily |
GHRP-2
GHRP-2 produces the largest GH pulse of the three. If raw GH amplitude per injection were the only thing that mattered, GHRP-2 would win.
What it costs you:
- Cortisol elevation. GHRP-2 raises cortisol meaningfully. For users already managing high training stress, poor sleep, or chronic stress, this is a real downside.
- Prolactin elevation. Moderate. Long-running prolactin elevation can affect libido, mood, and (in men) breast tissue sensitivity.
- Appetite increase. Less than GHRP-6 but still present.
GHRP-2 fits users who want the strongest GH stimulus per shot and who aren't worried about cortisol or prolactin. It's a less common choice today than it was a decade ago, mostly because Ipamorelin offers most of the GH effect with none of the off-target hits.
GHRP-6
GHRP-6's defining feature is appetite. The compound was originally noted for its dramatic effect on hunger — users on GHRP-6 frequently report aggressive hunger 30–60 minutes after injection.
This makes GHRP-6 useful for:
- Hardgainers struggling to eat enough during a bulk
- Recovery from illness or surgery where appetite is suppressed
- Underweight users trying to add mass
It makes GHRP-6 a poor choice for:
- Cutting cycles (the appetite spike sabotages the deficit)
- General body composition users (eating more isn't the goal)
The cortisol and prolactin profile mirrors GHRP-2 — moderately elevated, not catastrophic, but real. For users specifically chasing the appetite effect, GHRP-6 is uniquely positioned. For anyone else, Ipamorelin is the better tool.
Ipamorelin
Ipamorelin is the selective GHRP. It triggers GH release through the ghrelin receptor without significantly raising cortisol or prolactin, and without producing the hunger spike of GHRP-6.
The trade-off is GH amplitude — Ipamorelin's pulse is smaller than GHRP-2's. In practice this gap is closed by stacking with CJC-1295 (no DAC), which activates the GHRH receptor in parallel and amplifies the pulse. The Ipa+CJC stack produces a GH pulse comparable to or larger than GHRP-2 alone, without the cortisol and prolactin hit.
This is why Ipamorelin became the default GHRP. The selectivity profile turns a moderate-amplitude pulse into a clean, sustainable GH signal you can run for months.
See the full dosing breakdown in Ipamorelin protocol.
Side effect profile head-to-head
| Effect | GHRP-2 | GHRP-6 | Ipamorelin |
|---|---|---|---|
| Cortisol elevation | Notable | Notable | Minimal |
| Prolactin elevation | Moderate | Moderate | Minimal |
| Appetite spike | Moderate | Strong | Minimal |
| Water retention | Moderate | Moderate | Mild |
| Numbness or tingling | Occasional | Occasional | Rare |
| Lethargy or grogginess | Occasional | Occasional | Rare |
| Mood effects | Possible (prolactin) | Possible (prolactin) | Minimal |
The pattern is consistent: GHRP-2 and GHRP-6 trade off-target effects for raw potency. Ipamorelin trades a smaller pulse for a clean profile.
When each fits
| Situation | Best choice |
|---|---|
| First-time GHRP user | Ipamorelin |
| Pairing with CJC-1295 | Ipamorelin |
| Hardgainer needing appetite | GHRP-6 |
| Maximum GH per shot, side effects acceptable | GHRP-2 |
| Long-running protocol (12+ weeks) | Ipamorelin |
| Cutting cycle | Ipamorelin |
| Bulking with poor appetite | GHRP-6 |
What "selectivity" actually means
The GHS-R1a receptor signals through multiple downstream pathways. Ipamorelin's structure activates the GH-release pathway strongly while engaging the cortisol and prolactin pathways weakly. GHRP-2 and GHRP-6 don't make the same distinction — they activate all the downstream signals at once.
This isn't just theoretical. Bloodwork comparisons in published peptide research consistently show meaningful cortisol and prolactin elevation after GHRP-2 or GHRP-6 injection, and minimal change after Ipamorelin at equivalent GH-stimulating doses. The selectivity is the whole reason Ipamorelin exists as a distinct compound rather than a GHRP-2 knockoff.
A practical framework
If you can't decide:
- Default to Ipamorelin + CJC-1295 (no DAC). This is the most-reported, best-tolerated GHRP protocol and works for nearly all use cases.
- Use GHRP-6 only if you specifically need appetite stimulation. Don't use it because someone said it's "stronger."
- Use GHRP-2 only if you've tried Ipamorelin and want a larger per-shot pulse. Accept the cortisol and prolactin trade.
- Don't run GHRP-2 or GHRP-6 long-term. The cortisol and prolactin drift over months is real.