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GHRP-6

Growth HormoneResearch-Grade

Last reviewed: September 20, 2026 · Updated

Quick Facts

What it is
A lab-made peptide that signals the pituitary to release the body's own growth hormone — the original growth-hormone-releasing peptide, known for its signature intense hunger (via the ghrelin/NPY/AgRP appetite circuit) and a notable rise in cortisol and prolactin.
How it's taken
Subcutaneous injection or intranasal spray, on an empty stomach
Half-life
~15–30 minutes (plasma)
Typical research dose
100–300 mcg, one to three times daily, in 8–12 week cycles
Research status
Not FDA-approved — research use only.
On this page
  1. 1.Where to source GHRP-6
  2. 2.What is GHRP-6?
  3. 3.How does GHRP-6 work?
  4. 4.What is GHRP-6 used for?
  5. 5.How long does GHRP-6 take to work?
  6. 6.How is GHRP-6 dosed?
  7. 7.How is GHRP-6 administered?
  8. 8.What does GHRP-6 stack well with?
  9. 9.What are the side effects of GHRP-6?
  10. 10.Does GHRP-6 interact with other drugs?
  11. 11.How should GHRP-6 be stored?
  12. 12.What are the limitations of GHRP-6 research?
  13. 13.GHRP-6 FAQ
  14. 14.References
  15. 15.Published Studies
  16. 16.Prices and lab checks

Where to source GHRP-6

GHRP-6 is sold only as a research-grade peptide. The vendors highlighted below have been vetted for transparent third-party testing, traceable batch documentation, and verified discount codes.

Vital Core Research20% off

Vanguard Laboratory · per-lot certificates on each product listing

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Oasis Labs15% off

Bioviridian-tested · verifiable COAs

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Fusion Peptide15% off
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Peptides.gg15% off

Per-batch COAs

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What is GHRP-6?

GHRP-6 (Growth Hormone Releasing Peptide-6; developmental code SKF-110679; sequence His-D-Trp-Ala-Trp-D-Phe-Lys-NH2) is the original growth-hormone-releasing peptide, described by Bowers and colleagues in 1984 — the discovery that launched the entire GH-secretagogue field. It activates the ghrelin receptor (GHSR-1a) to release a pulse of growth hormone, and because it strongly engages the same appetite circuitry as ghrelin, it produces the most pronounced hunger of the common GHRPs. It is the least selective of the group, also raising cortisol and prolactin — which is why GHRP-2 and Ipamorelin are often preferred for cleaner, long-term GH stimulation. Most research pairs it with a GHRH analog such as CJC-1295. New to peptide research? Start with the basics

Reported benefits:

  • Pulsatile GH release via the ghrelin receptor (the founding GHRP)
  • Strong appetite stimulation — useful in appetite-loss and cachexia research
  • Raises IGF-1 downstream of GH; supports lean mass (extrapolated)
  • Synergizes with GHRH analogs (CJC-1295/sermorelin) for a larger GH pulse
  • Preclinical cytoprotective signals shared with the GHRP class
  • Caveat: least selective — notable cortisol/prolactin rise and hunger

Common research dose: No human trial has established a subcutaneous bolus dose; reported research-community practice is 100–300 mcg, 1–3 times daily, on an empty stomach. Timing is often built around the strong appetite spike. A human trial found a dose-related GH response by IV and intranasal routes, and community sources report that beyond ~1 mcg/kg, extra dose adds cortisol, not GH.

Where to buy: Prof. Peptide maintains a vetted list of peptide vendors with verified discount codes. See Verified Discount Codes for current options.

How does GHRP-6 work?

GHRP-6 is the original synthetic growth-hormone-releasing peptide. It activates the ghrelin/GH-secretagogue receptor (GHSR-1a) on pituitary somatotrophs and, importantly, on the appetite-driving neurons of the hypothalamus. This dual site of action is why GHRP-6 both releases a pulse of GH and produces strong hunger. It is the least selective of the common GHRPs — it also raises cortisol, prolactin, and ACTH.

  1. GHSR-1a receptor activation [1][3]. GHRP-6 (His-D-Trp-Ala-Trp-D-Phe-Lys-NH2) binds the ghrelin receptor on somatotrophs and hypothalamic neurons. Ghrelin, identified in 1999, is the endogenous ligand for this receptor [3]; GHRP-6 is the synthetic peptide that revealed the receptor's existence 15 years earlier [1].
  2. Calcium/PLC signaling. Receptor activation couples to Gq/11 → phospholipase-C → IP3 → intracellular calcium rise in somatotrophs, triggering GH release — a pathway distinct from the Gs/cAMP route used by GHRH analogs, which is the basis of GHRP + GHRH synergy.
  3. Appetite via NPY/AgRP neurons. GHRP-6 activates orexigenic NPY/AgRP neurons in the hypothalamic arcuate nucleus — the same circuit ghrelin uses. This produces the strong, fast hunger (15–30 minutes) that distinguishes GHRP-6 from the more GH-selective GHRPs.
  4. GH release + somatostatin suppression [2]. GHRP-6 amplifies pulsatile GH secretion and blunts somatostatin tone; in humans it raises GH and, with repeated dosing, IGF-1 [2].
  5. Low selectivity. Beyond GH, GHRP-6 raises cortisol, prolactin, and ACTH more than GHRP-2 and far more than ipamorelin — the trade-off for being the most ghrelin-like of the group.

What is GHRP-6 used for?

GHRP-6's research legacy is foundational — it established the GH-secretagogue field (Bowers, 1984) and has human data on GH/IGF-1 elevation. Its distinctive appetite effect makes it a tool in cachexia and appetite-loss research. Body-composition and anti-aging uses are extrapolated from GH physiology, not controlled GHRP-6 trials. It is not FDA-approved.

  1. GH stimulation [1][2]. GHRP-6 reliably releases GH in cell, animal, and human studies — the original demonstration that a small synthetic peptide could specifically provoke GH.
  2. IGF-1 elevation [2]. Repeated dosing raises IGF-1 in humans, the anabolic signal behind body-composition and recovery research.
  3. Appetite / cachexia research. GHRP-6's strong ghrelin-like hunger effect makes it a research tool for conditions of appetite loss and wasting.
  4. Cardiac and cytoprotective signals. Like other GHRPs, GHRP-6 shows cytoprotective effects in preclinical models via GH-secretagogue-receptor and related pathways — an area more developed for hexarelin.
  5. Limited long-term human data [4]. As the class review notes, controlled long-term efficacy and safety trials of GHRP-6 are lacking; most non-research use is off-label.

How long does GHRP-6 take to work?

GHRP-6 acts fast on both GH and appetite, with physical changes building over weeks. The GH pulse and hunger appear within roughly 15–30 minutes; IGF-1 rises over days of consistent dosing, and body-composition effects over 8–12 weeks.

The GH pulse and the hunger both appear within about 15–30 minutes of a subcutaneous dose — the appetite effect is more noticeable with GHRP-6 than with any other common GHRP. IGF-1 rises within days of consistent dosing, and body-composition changes build over 8–12 weeks. The plasma half-life is commonly reported as short (roughly 15–30 minutes), so each dose is described as a discrete pulse; bedtime dosing and an empty stomach are reported to matter more than sustained blood levels, though no published pharmacokinetic study or label has been identified establishing this figure for GHRP-6. The appetite response often diminishes somewhat over weeks of use.

How is GHRP-6 dosed?

No human trial has established a repeated subcutaneous, once-to-thrice-daily research dose for GHRP-6. The figures below are split into what the cited literature administered and, separately, community-reported practice.

Prof. Peptide reports what trials established and what research communities practice, labelled separately. Neither is a recommendation.

Need to calculate a dose?

Use the Prof. Peptide dosage calculator for accurate reconstitution and dosing math.

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What the cited literature administered

Human trial (dose-response, IV and intranasal). Hayashi et al. (Endocrinol Jpn, 1991, PMID 1915110) tested GHRP-6 in 6 healthy men. A single intravenous bolus of 1 mcg/kg produced a mean peak GH of about 54.9 mcg/L. Intranasal dosing was dose-related: peaks of roughly 7.5, 14.1, and 39.6 mcg/L GH at 5, 15, and 30 mcg/kg respectively — doses far higher than the IV bolus because intranasal delivery is far less efficient. In a repeated-dosing arm, seven consecutive intranasal doses of 15 mcg/kg every 8 hours were well tolerated with no attenuation of the GH response, and IGF-1 rose from 94.5 to 125.8 mcg/L over the course of treatment. Plasma prolactin and cortisol rose slightly but significantly after the IV dose, consistent with GHRP-6's low receptor selectivity. No subcutaneous dose-response data were found in this trial or elsewhere in the cited literature.

Community-reported practice (unverified)

Reported research-community practice — attributed to where it circulates, not to the trial above, and not independently verified by Prof. Peptide — is 100–300 mcg subcutaneously per bolus injection, once to three times daily, on an empty stomach, for 8–12 week cycles. This diverges from the cited trial in both route (subcutaneous bolus versus the trial’s IV bolus or intranasal dosing) and dose basis (a flat mcg figure versus the trial’s weight-based mcg/kg dosing, which for a roughly 80 kg adult would put the trial’s 1 mcg/kg IV dose around 80 mcg — within the low end of the community range, but by a different route). No source was found deriving the community subcutaneous figure from the trial’s own numbers.

GHRP-6 is typically stacked with CJC-1295 for dual-pathway GH release; the pre-blended GH Stack uses the same principle with ipamorelin.

The Prof. Peptide dosage calculator converts between milligram figures and syringe units for a given reconstitution; it performs the arithmetic and does not set a schedule.

How is GHRP-6 administered?

GHRP-6 is given as a subcutaneous injection using a small insulin syringe, on an empty stomach so food-driven insulin does not blunt the GH response. A strong hunger spike is reported 15–30 minutes after dosing. For syringe mechanics and units-vs-mcg conversion, see the syringes and injection technique guide.

  1. Route. Subcutaneous injection. Common sites: abdomen, thigh, upper arm.
  2. Time of day. Bedtime or pre-meal, depending on whether the appetite spike is wanted or avoided, on an empty stomach in all cases.
  3. With or without food. An empty stomach is reported required (2+ hours after eating, ~30 min before next meal) — insulin blunts GH release.
  4. Site rotation. Reported practice rotates sites each injection, staying at least 1 inch from the previous site.
  5. Appetite spike. Pronounced hunger is reported 15–30 minutes after dosing — the strongest of the common GHRPs.
  6. Missed dose. Reported practice skips and resumes the next scheduled dose, without doubling up.
  7. Cycle structure. 8–12 weeks on, with time off.

Timing context. GHRP-6's short half-life makes each dose a discrete GH pulse. The two practical variables are an empty stomach (insulin blunts GH) and how you handle the hunger — GHRP-6's appetite effect is strong enough that timing is often built around it. Dose size has a ceiling; more than ~1 mcg/kg mostly adds cortisol and prolactin.

AspectReported
FrequencyContinuous ghrelin-receptor-agonist exposure is documented to desensitize the receptor (Camiña et al., 2004, Endocrinology) — the real mechanism cited as the reason to cycle. The specific interval reported here is community practice, not itself trial-derived: 1–3× daily, cycled rather than continuous
Best time of dayBedtime or pre-meal — built around the appetite spike
FoodEmpty stomach required — 2+ hours after eating, 30+ min before next meal
Injection site rotationRotating between the abdomen, thigh, and upper arm without reusing the same site for the next injection is standard subcutaneous-injection practice — documented in FDA-approved injectable labels generally (e.g., Wegovy's and Mounjaro's own instructions to rotate with each dose), not specific to GHRP-6.
Half-life~15–30 minutes (plasma)
Steady-statePer-pulse effect — each dose triggers a discrete GH pulse plus a hunger window

Reconstitution math. GHRP-6 research vials are typically 5 mg. Because doses are small (100–300 mcg), 2 mL or 3 mL reconstitution gives more precise unit draws. All units below are measured on a U-100 insulin syringe (100 units = 1 mL). The table assumes a 5 mg vial.

BAC waterConcentration100 mcg dose200 mcg dose300 mcg dose500 mcg dose
1 mL5 mg/mL2 units4 units6 units10 units
2 mL2.5 mg/mL4 units8 units12 units20 units
3 mL1.67 mg/mL6 units12 units18 units30 units

Units vs mcg. At a 5 mg vial, each unit delivers 50 mcg at 1 mL reconstitution, 25 mcg at 2 mL, and 16.7 mcg at 3 mL. For a primer on reading insulin syringes, see our guide on syringes and injection technique.

What does GHRP-6 stack well with?

GHRP-6's canonical pairing is a GHRH analog (CJC-1295 or sermorelin) — different receptor, synergistic GH pulse. It does NOT stack usefully with other ghrelin-receptor agonists (GHRP-2, hexarelin, ipamorelin, MK-677) — redundant. Recovery peptides pair cleanly.

  1. CJC-1295 / sermorelin (GHRH analogs). CJC-1295 or Sermorelin activate the GHRH receptor for dual-pathway synergy. The GH Stack uses this principle.
  2. Recovery peptides. BPC-157 and TB-500 pair cleanly for tissue repair during a GH-driven block.
  3. Conflicts: other ghrelin-receptor agonists. GHRP-2, Hexarelin, Ipamorelin, and MK-677 hit the same receptor — combining is redundant.
  4. Resistance training. Exercise-induced GH release adds to the GHRP-6 pulse.

What are the side effects of GHRP-6?

GHRP-6's signature side effect is strong hunger. Because it is the least selective GHRP, it also raises cortisol, prolactin, and ACTH more than the others, and produces the usual GH-related water retention. Long-term controlled human safety data is limited.

Common (most users)

  1. Strong appetite spike. The defining effect — intense hunger 15–30 minutes after dosing.
  2. Injection-site reactions. Mild redness or irritation, usually brief.
  3. Mild water retention / tingling. GH-related; often eases with lower doses.

Less common (moderate)

  1. Cortisol / prolactin rise. Larger than GHRP-2; can cause lethargy or, at higher doses, prolactin-related effects.
  2. Mild headache or flushing. Inconsistent across users.
  3. Reduced insulin sensitivity. Sustained GH elevation can modestly raise fasting glucose.

Serious (rare)

  1. Long-term human safety data is limited. Most controlled studies are short-duration.
  2. Theoretical tumor-growth risk. GH/IGF-1 elevation could accelerate a pre-existing malignancy, so active cancer is treated as a theoretical exclusion in research contexts.

Because it is the least selective GHRP, GHRP-6 is often reserved for its appetite effect or short research use, with GHRP-2 or ipamorelin preferred for cleaner long-term GH stimulation. IGF-1 and glucose are what reported protocols monitor with sustained use.

Does GHRP-6 interact with other drugs?

GHRP-6's interactions are mainly redundancy with other ghrelin-receptor agonists and blunting by insulin/steroids. No major pharmacokinetic drug-drug interactions are reported.

  1. Insulin and corticosteroids. Both blunt GH release; time dosing away from meals and steroid administration.
  2. Other ghrelin-receptor agonists (GHRP-2, hexarelin, ipamorelin, MK-677). Redundant via the same receptor; no additive GH benefit.
  3. Direct human growth hormone (HGH). Generally unnecessary to combine — GHRP-6 stimulates endogenous GH; exogenous HGH bypasses regulatory feedback.
  4. No significant drug-drug pharmacokinetic interactions reported in published research.

How should GHRP-6 be stored?

  1. Lyophilized (powder) form: Store at -20°C for long-term storage; refrigerate at 2–8°C for short-term.
  2. Reconstituted solution: 2–8°C, refrigerated, is standard practice once dissolved. Prof. Peptide has not identified a manufacturer label, published study, or lab document establishing how long reconstituted research-grade GHRP-6 remains stable — this page does not state a duration as fact.
  3. Reconstitution uses bacteriostatic water for injection (BAC water). Swirl gently — do not shake.
  4. The reconstituted solution is never frozen.
  5. GHRP-6 is stored protected from light, in the original carton.
  6. A solution that is cloudy, discolored, or contains particles is discarded.

What are the limitations of GHRP-6 research?

GHRP-6 is historically important and well characterized on GH release, but it is not FDA-approved for any use and is the least selective of the common GHRPs. Body-composition and anti-aging claims rest on GH physiology, not controlled GHRP-6 trials. It is WADA-prohibited in sport.

GHRP-6 is not FDA-approved for any therapeutic use. Its historical role — establishing the GH-secretagogue field — does not translate into approved indications, and its low selectivity (appetite, cortisol, prolactin) makes it less suited to long-term use than newer secretagogues.

Evidence for body-composition, recovery, and anti-aging use is extrapolated from GH/IGF-1 physiology and clinical observation rather than controlled long-term trials of GHRP-6 itself.

The World Anti-Doping Agency prohibits GHRP-6 in sport under Section S2 (peptide hormones/secretagogues). Research-grade material is sold for laboratory use only and is not approved for human consumption.

GHRP-6 FAQ

How is GHRP-6 different from GHRP-2 and Ipamorelin?

GHRP-6 is the original growth-hormone-releasing peptide and the least selective of the three. It produces the strongest appetite response (it most closely mimics ghrelin) and raises cortisol, prolactin, and ACTH along with GH. GHRP-2 is a more potent, somewhat cleaner GH releaser, and Ipamorelin is the most selective (GH-only). GHRP-6 is chosen when the intense hunger effect is wanted or as the classic reference compound.

Why does GHRP-6 make me so hungry?

That is its defining feature. GHRP-6 activates the ghrelin receptor and, through it, the appetite-driving NPY/AgRP neurons in the hypothalamus — the same circuitry the hunger hormone ghrelin uses. Intense hunger typically appears 15–30 minutes after a dose. It is the strongest appetite effect of the common GHRPs and is why GHRP-6 is studied in appetite-loss and cachexia research.

Does GHRP-6 raise cortisol?

Yes, more than GHRP-2 and much more than ipamorelin. GHRP-6 raises cortisol, prolactin, and ACTH alongside GH — a consequence of its low selectivity. This is the main reason many long-term protocols favor GHRP-2 or ipamorelin instead, reserving GHRP-6 for its appetite effect or short research use.

Should I stack GHRP-6 with CJC-1295?

Yes — the standard pairing. GHRP-6 hits the ghrelin receptor while CJC-1295 hits the GHRH receptor, producing a larger combined GH pulse than either alone. Stacking GHRP-6 with another ghrelin-receptor agonist (GHRP-2, hexarelin, ipamorelin, MK-677) is redundant.

How quickly does GHRP-6 work?

The GH pulse and the hunger both appear fast — within roughly 15–30 minutes of a subcutaneous dose. IGF-1 rises over days of consistent dosing, and body-composition effects build over weeks. The plasma half-life is short (roughly 15–30 minutes), so timing matters more than blood levels.

Where can I buy GHRP-6?

GHRP-6 is sold by specialty research-peptide vendors. Prof. Peptide maintains a list of vetted vendors with verified discount codes — see Verified Discount Codes .

References

  1. Bowers CY, Momany FA, Reynolds GA, Hong A. 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;114(5):1537-45. https://pubmed.ncbi.nlm.nih.gov/6714155/
  2. Hayashi S, Okimura Y, Yagi H, et al. Intranasal administration of His-D-Trp-Ala-Trp-D-Phe-LysNH2 (growth hormone releasing peptide) increased plasma growth hormone and insulin-like growth factor-I levels in normal men. Endocrinol Jpn. 1991;38(1):15-21. https://pubmed.ncbi.nlm.nih.gov/1915110/
  3. Kojima M, Hosoda H, Date Y, et al. Ghrelin is a growth-hormone-releasing acylated peptide from stomach. Nature. 1999;402(6762):656-60. https://pubmed.ncbi.nlm.nih.gov/10604470/
  4. Sigalos JT, Pastuszak AW. The Safety and Efficacy of Growth Hormone Secretagogues. Sex Med Rev. 2018;6(1):45-53. https://pubmed.ncbi.nlm.nih.gov/28400207/

Published Studies

Plain-English summaries of the peer-reviewed studies behind the claims above. Click any title to read the source paper.

Endocrinology / PubMed · 1984Abstract open
On the in vitro and in vivo activity of a new synthetic hexapeptide that acts on the pituitary to specifically release growth hormone →

Bowers CY, Momany FA, Reynolds GA, Hong A

The founding paper of the entire GHRP class — it introduced the hexapeptide His-D-Trp-Ala-Trp-D-Phe-Lys-NH2 (GHRP-6) and showed it releases GH specifically, without releasing LH, FSH, TSH, or prolactin in the assay, across multiple species. Every later GH secretagogue (GHRP-2, hexarelin, ipamorelin, MK-677) descends from this discovery, which is why GHRP-6 is treated as the reference compound of the class.

Endocrinol Jpn / PubMed · 1991Abstract open
Intranasal administration of GHRP (His-D-Trp-Ala-Trp-D-Phe-LysNH2) increased plasma GH and IGF-I levels in normal men →

Hayashi S, Okimura Y, Bowers CY, Chihara K, et al.

A human study showing that GHRP-6 stimulates GH secretion and raises IGF-1 in healthy men, with repeated dosing producing sustained IGF-1 elevation — an early demonstration that the GH pulse translates into a downstream anabolic signal in people, not just in cell and animal models.

Nature / PubMed · 1999Abstract open
Ghrelin is a growth-hormone-releasing acylated peptide from stomach →

Kojima M, Hosoda H, Date Y, et al.

The identification of ghrelin as the natural endogenous ligand of the growth-hormone-secretagogue receptor (GHSR-1a) — the receptor GHRP-6 had been activating for 15 years before its natural hormone was found. This paper explains why GHRP-6 both releases GH and drives hunger: it is a synthetic mimic of the body's own hunger-and-GH hormone.

Sex Med Rev / PubMed · 2018Open Access
The Safety and Efficacy of Growth Hormone Secretagogues →

Sigalos JT, Pastuszak AW

A clinical review of the GH-secretagogue class that places GHRP-6 in context: robust GH release but the least selective of the group, with appetite, cortisol, and prolactin effects. It is candid about the thin long-term human safety data across the class — a useful evidence-honest anchor for GHRP-6's real standing.

Prices and lab checks

Lowest price per mg

Lowest price per mg after Prof. Peptide's code, from the GHRP-6 price comparison.

  1. Fusion Peptide logo
    Fusion Peptide
    $2.01/mg
    10 mg · In stock · pulled October 24, 2026
  2. Real Peptides logo
    Real Peptides
    $2.40/mg
    10 mg · In stock · pulled October 24, 2026
  3. Alpha Peptides logo
    Alpha Peptides
    $2.58/mg
    5 mg · Out of stock · pulled October 24, 2026
  4. Solution Peptides logo
    Solution Peptides
    $2.66/mg
    5 mg · Out of stock · pulled October 24, 2026
  5. Healius Peptides logo
    Healius Peptides
    $2.70/mg
    10 mg · In stock · pulled October 24, 2026

Rows in the comparison's own order, up to five. Out-of-stock rows are included and each vial size is its own row; a vendor without a Prof. Peptide code shows its own price. Each date is that vendor's latest price pull.

Full comparison across 21 vendors

Median listed price per mg: $4.76 (July 26, 2026, 12 listings) → $3.95 (October 24, 2026, 30 listings); more vendors were added over the period.

Certificates checked at the lab

1 vendor with a GHRP-6 certificate Prof. Peptide matched at the issuing laboratory’s own lookup, listed alphabetically. A further 19 vendors carrying GHRP-6 in the price data name a testing laboratory, with no GHRP-6 certificate matched at the lab so far.

A match means the laboratory's own lookup returned the certificate as the vendor published it. It covers that certificate's lot, not the vendor's other lots or products.

Growth HormoneGHRPGHSR AgonistResearch-Grade

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