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The Peptide Effect
Comparison

GHRP-2 vs GHRP-6

GHRP-2 and GHRP-6 are both hexapeptide growth hormone releasing peptides that stimulate GH secretion through the ghrelin receptor (GHS-R1a), but they differ in potency, selectivity, and side effect profiles. GHRP-2 is considered the more potent GH releaser with less appetite stimulation, making it preferred for lean body composition goals. GHRP-6 triggers a stronger ghrelin-like hunger response, which can be beneficial during bulking phases but problematic for those trying to control caloric intake. Both peptides also moderately elevate cortisol and prolactin — a key disadvantage compared to the newer, more selective ipamorelin.

Side-by-side comparison diagram of GHRP-2 and GHRP-6 mechanisms of action
Conceptual comparison — not to scale

Head-to-Head Comparison

CriteriaGHRP-2GHRP-6
Primary mechanismGhrelin receptor (GHS-R1a) agonist with high GH release potencyGhrelin receptor (GHS-R1a) agonist with strong ghrelin-mimetic activity
GH release potencySlightly more potent GH release per mcg compared to GHRP-6Strong GH release but slightly less potent than GHRP-2 on a per-mcg basis
Appetite stimulationModerate — noticeable but manageable increase in hungerStrong — intense hunger within 15–20 minutes of injection, lasting 30–60 minutes
Cortisol elevationModerate increase — higher than ipamorelin but generally tolerableModerate increase — similar to GHRP-2, dose-dependent
Prolactin elevationMild to moderate increase at standard dosesMild to moderate increase — comparable to GHRP-2
Typical dosage100–300 mcg subcutaneous, 2–3× daily100–300 mcg subcutaneous, 2–3× daily
Half-life~30 minutes (GH peak at 15–30 min post-injection)~20–30 minutes (GH peak at 15–30 min post-injection)
Effect on gastric motilityMinimal effect on gut motilityIncreases gastric motility and stomach contractions (true ghrelin mimicry)
Ideal use caseCutting or recomposition — strong GH release without overwhelming hungerBulking — strong GH release plus appetite stimulation supports caloric surplus
Synergy with GHRH analogsExcellent — standard stack with CJC-1295 or sermorelin for synergistic GH pulseExcellent — strong synergy with CJC-1295 or sermorelin
Research depthExtensive — one of the most studied GHRPs with broad clinical trial dataExtensive — one of the earliest GHRPs discovered, well-characterized pharmacology
Approximate monthly cost$30–$70 (research grade); $150–$300 (clinic)$25–$60 (research grade); $150–$300 (clinic)

When to Choose Each

Choose GHRP-2

Cutting and recomposition phases, users who want potent GH release without intense hunger, those stacking with GHRH analogs for maximum GH output

Choose GHRP-6

Bulking phases where increased appetite is desired, hard-gainers who struggle with caloric intake, users who want strong GH release and do not mind the hunger spike

Verdict

GHRP-2 is the better all-around choice for most users due to its slightly higher GH release potency and more manageable appetite stimulation. It is particularly well-suited for cutting, recomposition, or anyone who does not want dramatic hunger spikes. GHRP-6 is specifically useful during bulking phases where the intense appetite stimulation is a feature rather than a bug — it can help users who struggle to eat enough reach their caloric targets. Both peptides are inferior to ipamorelin in terms of selectivity (cortisol/prolactin impact), so users who prioritize clean GH release with no hormonal side effects should consider ipamorelin instead.

References

  1. Comparison of growth hormone releasing peptide-2 (GHRP-2) and growth hormone releasing peptide-6 (GHRP-6) on GH secretion in humans (1997) — PubMed
  2. Growth hormone-releasing peptides — mechanism and clinical applications (2002) — PubMed
  3. GHRP-2 stimulates GH secretion through hypothalamic and pituitary mechanisms (1999) — PubMed
  4. The growth hormone secretagogue receptor — a decade of discovery (2005) — PubMed
  5. Appetite-stimulating effects of growth hormone releasing peptide-6 and its analogs (2004) — PubMed

Frequently Asked Questions

Why not just use ipamorelin instead of GHRP-2 or GHRP-6?
Ipamorelin is more selective and does not raise cortisol or prolactin, making it a cleaner option. However, GHRP-2 may produce a slightly stronger GH pulse per dose, and GHRP-6 provides useful appetite stimulation for bulking. Some users also find GHRP-2 and GHRP-6 more cost-effective. If side effect minimization is the priority, ipamorelin is the better choice.
How intense is the hunger from GHRP-6?
GHRP-6 can cause very intense hunger within 15–20 minutes of injection, often described as ravenous. This hunger spike typically lasts 30–60 minutes. It is one of the most reliable appetite stimulants in the peptide world. GHRP-2 also increases appetite but to a significantly lesser degree — most users describe it as a mild increase rather than an overwhelming urge to eat.
Should I worry about cortisol and prolactin elevation from these peptides?
At standard doses (100–300 mcg), the cortisol and prolactin elevation from GHRP-2 and GHRP-6 is generally mild and transient. However, at higher doses or with chronic use, these elevations can become clinically relevant. Monitor blood work every 2–3 months. If cortisol or prolactin becomes a concern, switching to ipamorelin or adding low-dose vitamin B6 (P-5-P form) for prolactin management is advisable.
How long should I cycle GHRP-2 or GHRP-6?
Common protocols reported in the peptide community run 8 to 12 weeks on followed by a 4-week break, though some practitioners prescribe longer continuous use with regular blood work monitoring. Unlike hexarelin, neither GHRP-2 nor GHRP-6 shows significant receptor desensitization at standard doses, so the cycling rationale is primarily to manage cortisol and prolactin accumulation rather than efficacy loss. Consult a healthcare provider to determine the most appropriate protocol duration and monitoring schedule for your situation.
Are GHRP-2 and GHRP-6 legal to purchase?
The regulatory status of GHRP-2 and GHRP-6 varies by jurisdiction. In the United States, they are available as research chemicals and are not FDA-approved for human use. Some compounding pharmacies offer them under physician supervision. In Australia, they are classified as Schedule 4 prescription-only substances. WADA prohibits both peptides for competitive athletes. It is important to check your local regulations and consult a healthcare provider before considering use.

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