GHRP Peptides

Growth hormone releasing peptide

Mechanism

GHRPs (growth hormone releasing peptides) are a family of synthetic peptides that stimulate the pituitary gland to release growth hormone by activating the ghrelin receptor (GHS-R1a). The family includes GHRP-2, GHRP-6, hexarelin, and ipamorelin, each with slightly different receptor selectivity and side effect profiles. They are typically combined with GHRH analogs (like CJC-1295) for synergistic GH release.

The key distinction between GHRPs is their selectivity. Ipamorelin is the most selective, producing GH release with minimal effects on cortisol, prolactin, or appetite. GHRP-6 is the least selective, also stimulating appetite and raising cortisol and prolactin. GHRP-2 falls in between. Hexarelin produces the strongest GH release but also the most cortisol and prolactin elevation. Choosing the right GHRP depends on which side effects are acceptable for your goals.

This page collects every GHRP on PeptideWiki. Browse individual profiles for specific receptor profiles, dosing, and safety data.

Peptides (4)

MK-677 (Ibutamoren)

Growth Hormone / IGF-1 Axis

MK-677 (Ibutamoren) is an oral (non-injectable) compound that triggers growth hormone release by mimicking the hunger hormone ghrelin. Research focuses on increasing growth hormone and IGF-1 levels, improving sleep quality, body composition, and bone density.

GHRP-6

Growth Hormone / IGF-1 Axis

GHRP-6 (Growth Hormone Releasing Peptide-6) is a six-amino-acid peptide that triggers growth hormone release through the ghrelin (hunger hormone) receptor. It is known for strong growth hormone release but also significant appetite stimulation.

Hexarelin

Growth Hormone / IGF-1 Axis

Hexarelin is a synthetic six-amino-acid peptide and one of the most potent compounds that trigger growth hormone release. Beyond its growth hormone effects, research also shows heart-protective properties that work independently of growth hormone.

GHRP-2

Growth Hormone / IGF-1 Axis

GHRP-2 (Growth Hormone Releasing Peptide-2) is a synthetic six-amino-acid peptide that triggers growth hormone release. It is considered more potent than GHRP-6 with less appetite stimulation.

Frequently Asked Questions

Ipamorelin: most selective, clean GH release with minimal cortisol/prolactin/appetite effects. Best for those who want pure GH elevation without side effects. GHRP-2: moderate selectivity, stronger GH release than ipamorelin with slight cortisol and prolactin elevation, mild appetite increase. Good balance of potency and tolerability. GHRP-6: least selective, strong appetite stimulation (useful for bulking), notable cortisol and prolactin elevation. Best for those who want appetite increase alongside GH. Hexarelin: strongest single-dose GH release but the most cortisol and prolactin, and it develops desensitization (reduced response) with chronic use faster than others.

GHRPs and GHRH analogs (CJC-1295) stimulate GH release through different mechanisms: GHRPs activate the ghrelin receptor while CJC-1295 activates the GHRH receptor. Used together, they produce a synergistic effect, meaning the combined GH release is significantly greater than either alone. The analogy is that GHRH tells the pituitary how much GH to release per pulse, while GHRPs increase the number and frequency of pulses. The combination produces GH levels closer to those achieved with direct HGH injection but through the body's natural release mechanism.

Hexarelin shows the most rapid desensitization, with reduced GH response after 4-8 weeks of continuous use. GHRP-2 and GHRP-6 show slower desensitization over months. Ipamorelin appears to maintain its GH-releasing effect the longest with minimal desensitization. To manage this, users typically cycle GHRPs (5 days on, 2 days off, or 8 weeks on, 4 weeks off) or rotate between different GHRPs. Combining with CJC-1295 may also help maintain response because it works through a separate receptor.

GHRPs are most effective when taken on an empty stomach, typically 30-60 minutes before bed (to amplify the natural nighttime GH pulse) or first thing in the morning before eating. Food, especially carbohydrates and fats, blunts the GH response significantly. The pre-bed dose is most popular because it aligns with the body's natural GH release pattern and supports recovery during sleep. Some protocols add a second dose in the morning or pre-workout, always fasted.

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