GHRP-6
Growth Hormone Releasing Peptide-6 · SK&F 110679 · GHRP
The original GHRP: solid GH release and the strongest hunger response of the group.
Typical dose
100 mcg
2-3x daily
Range
100–300
mcg
Half-life
2.5 h
see Dosing
Evidence
Early human
Subcutaneous · Intramuscular · Intravenous
What it is
GHRP-6 is the hexapeptide Cyril Bowers' group described in 1984, the compound that opened the entire growth hormone secretagogue field and led, indirectly, to the discovery of ghrelin itself. Everything from GHRP-2 to MK-677 descends from it.
Its defining feature in practice is appetite. GHRP-6 produces hunger strong enough that people use it as an appetite drug rather than a GH drug. That is genuinely useful if you are struggling to eat through a bulk and close to disqualifying if you are dieting.
GH release is real but sits below GHRP-2 and hexarelin per microgram, and it is not selective: cortisol and prolactin rise at higher doses. A separate line of Cuban research has pursued GHRP-6 for cytoprotection after myocardial infarction and for wound healing, which has little bearing on how it is used in this community.
How it works
GHRP-6 is an agonist at GHS-R1a, the ghrelin receptor, on pituitary somatotrophs and in the hypothalamic arcuate nucleus. It releases GH two ways at once, acting directly on the pituitary and suppressing somatostatin. Human work shows the response leans heavily on your own GHRH: block endogenous GHRH and most of the GH response to GHRP-6 disappears.
The same arcuate receptors drive the NPY and AgRP neurons that generate hunger, which is where the appetite effect comes from. That is intrinsic to the mechanism rather than a high-dose artefact, so unlike GHRP-2's milder bump it does not go away by simply dosing lower.
Dosing
About 100 mcg, roughly 1 mcg/kg, captures most of the GH response. Higher doses mainly buy more hunger, cortisol and prolactin.
Reconstitution calculator
Pre-loaded with GHRP-6’s vial size, water volume and typical dose. Change anything.
Typical: 100 mcg · range 100–300
Draw to
4 u
0.04 mL · 100 mcg
Concentration
2.5 mg/mL
25 mcg per unit
Doses per vial
50
Vial lasts
2 weeks 3 days
Draw to 4 units on the barrel.
Once mixed
Refrigerate at 2-8 C away from light and use within 3-4 weeks. Do not freeze the reconstituted vial.
Aim the bacteriostatic water at the vial wall and swirl until clear rather than shaking. A 5 mg vial in 2 mL gives 2,500 mcg/mL, making 100 mcg a fiddly 4 units; if you dose in 100 mcg steps, 5 mL gives 1,000 mcg/mL and a clean 10 units per dose.
Storage
Before mixing
Sealed and dry it keeps for months at 2-8 C and for years at -20 C, and survives short room-temperature transit.
After mixing
Refrigerate at 2-8 C away from light and use within 3-4 weeks. Do not freeze the reconstituted vial.
Reported benefits
- ▪Strong, reliable appetite stimulation, the most useful GHRP for forcing food down
- ▪Genuine GH release with marked synergy alongside a GHRH analogue
- ▪Cheapest and most widely available of the GHRPs
- ▪Improved sleep depth commonly reported from the pre-bed dose
- ▪The longest track record of the classic GHRPs, in continuous study since 1984
- ▪Animal and early human work on wound healing and cardiac cytoprotection
Side effects
- ▪Hunger that many people find unmanageable while dieting
- ▪Cortisol, ACTH and prolactin rise at doses above roughly 100 mcg
- ▪Water retention and puffy extremities
- ▪Head rush, flushing and sweating in the minutes after injecting
- ▪Tingling or numb fingers at higher doses
- ▪Reduced insulin sensitivity on long, high-dose use
- ▪Injection-site redness or a transient welt
Do not use if
- ▪Active or suspected cancer
- ▪Uncontrolled diabetes or significant insulin resistance
- ▪Existing hyperprolactinaemia
- ▪Untreated pituitary or hypothalamic disease
- ▪Pregnancy and breastfeeding
Evidence level — Early human
Small or early-phase human studies only.
Not approved for human use in any market, sold as a research chemical, and prohibited by WADA at all times.
Commonly run with
CJC-1295 no-DAC
Short-acting GHRH fragment that sharpens one GH pulse, almost always run with a GHRP.
100 mcg · 1-3x daily
CJC-1295 with DAC
Albumin-binding GHRH analogue that lifts GH and IGF-1 for days from one injection.
1000 mcg · 1-2x weekly
Sermorelin
The first 29 amino acids of human GHRH, once approved as Geref and now compounded.
300 mcg · once nightly, 5-7 nights per week
Tesamorelin
The only FDA-approved GHRH analogue, proven to shrink visceral abdominal fat.
2 mg · once daily
GHRP-6 FAQ
How bad is the hunger really?+
It comes on 10-20 minutes after the shot, peaks hard for roughly half an hour, then fades. Most people describe it as sharper than normal hunger rather than longer. It is the single reason GHRP-6 gets used in a bulk and avoided in a cut.
Does the hunger fade if I keep using it?+
Partially. Most users report the appetite effect blunts over the first two to three weeks while the GH effect holds up longer. Do not count on it disappearing entirely, and do not plan a diet around it fading.
Is GHRP-6 worse for you than ipamorelin?+
It is less selective, so cortisol and prolactin move more at the same relative GH output, and it hits appetite far harder. At 100 mcg per dose in a healthy person the endocrine effects are small. The gap widens as the dose goes up.
Why is its half-life listed as 2.5 hours when everyone says 20 minutes?+
Because those are two different things. A published PK study in healthy men found a fast 8-minute distribution phase and a 2.5-hour terminal elimination phase. The 20-minute figure people repeat describes how long the GH pulse lasts, which is what actually drives dosing frequency.
Can I run it with MK-677?+
There is no point. MK-677 is an orally active ghrelin-receptor agonist working on the same receptor, so stacking them mostly compounds the hunger, water retention and insulin resistance without buying much extra GH. Pair a GHRP with a GHRH analogue instead.
References
- 1.On the in vitro and in vivo activity of a new synthetic hexapeptide that acts on the pituitary to specifically release growth hormone — Endocrinology (1984) PMID 6714155
- 2.Growth hormone (GH)-releasing peptide-6 requires endogenous hypothalamic GH-releasing hormone for maximal GH stimulation — The Journal of Clinical Endocrinology and Metabolism (1998) PMID 9543138
- 3.Pharmacokinetic study of growth hormone-releasing peptide 6 (GHRP-6) in nine male healthy volunteers — European Journal of Pharmaceutical Sciences (2013) PMID 23099431
- 4.Growth-hormone-releasing peptide 6 (GHRP6) prevents oxidant cytotoxicity and reduces myocardial necrosis in a model of acute myocardial infarction — Clinical Science (2007) PMID 16989643
More gh secretagogues
CJC-1295 no-DAC
Short-acting GHRH fragment that sharpens one GH pulse, almost always run with a GHRP.
100 mcg · 1-3x daily
CJC-1295 with DAC
Albumin-binding GHRH analogue that lifts GH and IGF-1 for days from one injection.
1000 mcg · 1-2x weekly
GHRP-2
Potent, well-studied GHRP with a bigger pulse than ipamorelin and more cortisol.
100 mcg · 2-3x daily
Hexarelin
The most potent GHRP, and the fastest to stop working if you run it continuously.
100 mcg · 1-2x daily