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GHRP-2

Growth HormoneResearch-Grade

Last reviewed: July 21, 2026

Quick Facts

What it is
A lab-made peptide that signals the pituitary to release the body's own growth hormone — a potent GH secretagogue that also stimulates appetite through the ghrelin receptor.
How it's taken
Subcutaneous injection in research; a single IV dose for the Japanese diagnostic (pralmorelin); oral administration also studied
Half-life
~30 minutes (plasma)
Typical research dose
100–300 mcg, one to three times daily on an empty stomach, in 8–12 week cycles
Research status
Not FDA-approved — but approved in Japan as pralmorelin, a GH-stimulation diagnostic. Research use only elsewhere; WADA-prohibited (S2).
On this page
  1. 1.What is GHRP-2?
  2. 2.How does GHRP-2 work?
  3. 3.What is GHRP-2 used for?
  4. 4.How long does GHRP-2 take to work?
  5. 5.How is GHRP-2 dosed?
  6. 6.How is GHRP-2 administered?
  7. 7.What does GHRP-2 stack well with?
  8. 8.What are the side effects of GHRP-2?
  9. 9.Does GHRP-2 interact with other drugs?
  10. 10.How should GHRP-2 be stored?
  11. 11.What are the limitations of GHRP-2 research?
  12. 12.Where to source GHRP-2
  13. 13.GHRP-2 FAQ
  14. 14.References
  15. 15.Published Studies

What is GHRP-2?

GHRP-2 (pralmorelin, also carried under the developmental codes KP-102 and GHRP-KP; D-Ala-D-2-Nal-Ala-Trp-D-Phe-Lys-NH2) is a synthetic hexapeptide growth-hormone secretagogue that activates the ghrelin receptor (GHSR-1a). It is more potent at releasing GH than the original GHRP-6 and more GH-selective, though not fully cortisol-sparing like Ipamorelin. Its GH-releasing action is reliable enough that it is used as an approved diagnostic test for GH deficiency in Japan. Most research combines it with a GHRH analog such as CJC-1295 for a larger, dual-pathway GH pulse. New to peptide research? Start with the basics →

Reported benefits:

  • Potent, reliable pulsatile GH release via the ghrelin receptor
  • Raises IGF-1 downstream of GH; supports lean mass and fat loss (extrapolated)
  • Appetite stimulation (ghrelin-like) — useful in cachexia research
  • Validated GH-provocative diagnostic (approved as pralmorelin in Japan)
  • Synergizes with GHRH analogs (CJC-1295/sermorelin) for a bigger GH pulse
  • Caveat: not cortisol-sparing — modest cortisol/prolactin rise

Common research dose: Most protocols use 100–300 mcg subcutaneously, 1–3 times daily, on an empty stomach — bedtime is the most common single-dose timing. Doses much above ~1 mcg/kg add cortisol, not GH.

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

How does GHRP-2 work?

GHRP-2 is a synthetic hexapeptide that activates the ghrelin/growth-hormone-secretagogue receptor (GHSR-1a) on pituitary somatotrophs and hypothalamic neurons — the same receptor the natural hormone ghrelin uses. Receptor activation drives a Gq/PLC calcium cascade that triggers a pulse of growth-hormone release, while also amplifying GHRH signaling and blunting somatostatin. Unlike ipamorelin, GHRP-2 is not fully GH-selective — it produces a modest rise in cortisol, prolactin, and ACTH.

  1. GHSR-1a receptor activation [1][2]. GHRP-2 binds the ghrelin receptor (GHSR-1a) on somatotrophs and in the hypothalamus. This is the receptor for which ghrelin is the endogenous ligand [2]; GHRP-2 is a synthetic ghrelin mimic optimized for GH release.
  2. Calcium/PLC signaling [1]. Receptor activation couples to Gq/11, driving phospholipase-C and IP3-mediated intracellular calcium rise in somatotrophs — a mechanism distinct from the Gs/cAMP pathway used by GHRH-class peptides, which is why GHRP-2 and CJC-1295 act synergistically.
  3. Pulsatile GH release + somatostatin suppression [4]. GHRP-2 amplifies the natural pulsatile GH pattern rather than producing a continuous flood, and it reduces the inhibitory tone of somatostatin — preserving the feedback loops that make secretagogues safer than direct GH.
  4. Appetite via the ghrelin pathway [3]. Because GHRP-2 activates the ghrelin receptor, it also stimulates appetite — human infusion increased food intake ~36% versus saline [3]. This is a smaller effect than GHRP-6 but a defining feature of the ghrelin-receptor agonists.
  5. Partial selectivity [4]. GHRP-2 raises cortisol, prolactin, and ACTH modestly alongside GH — more than ipamorelin, less than GHRP-6. This is the trade-off for its strong GH-releasing potency.

What is GHRP-2 used for?

GHRP-2's evidence base is the strongest of the classic GHRPs on the GH axis: it is a validated GH-stimulation diagnostic (approved as pralmorelin in Japan), with human data on GH/IGF-1 elevation and appetite. Body-composition and anti-aging uses are extrapolated from GH physiology and clinical practice rather than controlled trials. It is not FDA-approved.

  1. Growth-hormone stimulation / diagnostics [4]. GHRP-2 reliably provokes a GH pulse; a single 100 mcg IV dose is used as a provocative test for GH deficiency, and it is approved for this diagnostic use in Japan (pralmorelin).
  2. IGF-1 elevation [4]. Repeated GHRP-2 dosing raises IGF-1 downstream of GH — the mechanism behind its research use for body composition and recovery.
  3. Appetite and body weight [3][5]. Human and pediatric studies document increased food intake and body weight with GHRP-2, reflecting its ghrelin-receptor activity — relevant to research on cachexia and appetite loss.
  4. Body composition (extrapolated). Lean-mass and fat-loss effects are inferred from GH/IGF-1 physiology and clinical observation, not from controlled GHRP-2 trials.
  5. Limited long-term human data [6]. As the class review notes, controlled long-term safety and efficacy trials of GHRP-2 are lacking; most non-diagnostic use is off-label or research-grade.

How long does GHRP-2 take to work?

GHRP-2 produces an immediate GH pulse but cumulative physical effects that build over weeks. The GH peak occurs within roughly 15–60 minutes of a dose; downstream IGF-1 elevation appears within days of consistent dosing, and body-composition changes over 8–12 weeks.

The GH response is fast — a measurable pulse within about 15–60 minutes of a subcutaneous dose, which is why GHRP-2 works as a provocative diagnostic. IGF-1 rises within days of consistent dosing. Subjective and body-composition changes (recovery, lean mass, fat loss) build over 8–12 weeks. Because the plasma half-life is short (roughly 30 minutes), each dose is a discrete pulse — timing (bedtime, empty stomach) matters more than sustained blood levels. Expect a transient appetite increase after dosing.

How is GHRP-2 dosed?

GHRP-2 is given by subcutaneous injection. Research protocols commonly use 100–300 mcg per dose, once to three times daily, on an empty stomach — bedtime is the most common single-dose timing. It is frequently combined with CJC-1295 for dual-pathway GH release.

  1. Standard dose. 100–300 mcg subcutaneously per injection, on an empty stomach.
  2. Bedtime dosing. A single dose 30–60 minutes before sleep aligns with the natural overnight GH peak and lets you sleep through the appetite spike.
  3. Multiple daily dosing. 100–200 mcg 2–3× daily (e.g. morning, mid-day, bedtime) for sustained effect.
  4. Saturation caveat. Doses much above ~1 mcg/kg give little extra GH but more cortisol/prolactin — higher is not better with GHRP-2.
  5. Cycle length. 8–12 weeks on, with time off; often run alongside a GHRH analog.

GHRP-2 is most often stacked with CJC-1295 (ghrelin receptor + GHRH receptor = synergistic GH release). The pre-blended GH Stack uses the same principle with ipamorelin.

Need to calculate your dose? Convert mg to syringe units and plan reconstitution with the dosage calculator →.

How is GHRP-2 administered?

GHRP-2 is given as a subcutaneous injection using a small insulin syringe, on an empty stomach — food-driven insulin blunts the GH response. Bedtime dosing aligns with the natural overnight GH peak. 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 is most common; a pre-workout dose is sometimes added. Empty stomach in all cases.
  3. With or without food. Empty stomach required (2+ hours after eating, no food for ~30 min after) — insulin blunts GH release.
  4. Site rotation. Rotate sites each injection; stay at least 1 inch from the previous site.
  5. Appetite spike. Expect increased hunger for 30–60 minutes after dosing (ghrelin-receptor activation).
  6. Missed dose. Skip and resume the next scheduled dose; do not double up.
  7. Cycle structure. 8–12 weeks on, with time off.

Timing context. GHRP-2's short (~30-minute) half-life means each dose is a discrete GH pulse. Stacking the dose onto the natural overnight GH surge (bedtime) and keeping the stomach empty are the two variables that most affect the response. Dose size has a ceiling — beyond roughly 1 mcg/kg, additional GHRP-2 mostly adds cortisol and prolactin, not GH.

AspectRecommendation
Frequency1–3× daily during the cycle (most users dose once at bedtime)
Best time of dayBedtime preferred — aligns with the natural overnight GH peak
FoodEmpty stomach required — 2+ hours after eating, 30+ min before next meal
Injection site rotationRotate between abdomen, thigh, upper arm
Half-life~30 minutes (plasma)
Steady-statePer-pulse effect — each dose triggers a discrete GH pulse rather than a sustained level

Reconstitution math. GHRP-2 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-2 stack well with?

GHRP-2'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-6, hexarelin, ipamorelin, MK-677) — those are redundant. Recovery peptides pair cleanly.

  1. CJC-1295 / sermorelin (GHRH analogs). CJC-1295 or Sermorelin activate the GHRH receptor while GHRP-2 activates the ghrelin receptor — 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 anabolic block.
  3. Avoid: other ghrelin-receptor agonists. GHRP-6, Hexarelin, Ipamorelin, and MK-677 hit the same receptor — combining them is redundant.
  4. Resistance training. Exercise-induced GH release adds to the GHRP-2 pulse.

What are the side effects of GHRP-2?

GHRP-2 is generally well tolerated but is not cortisol-sparing. The most common effects are a transient appetite spike, mild injection-site reactions, and GH-related water retention or tingling. Its distinguishing caveat versus ipamorelin is a modest rise in cortisol and prolactin. Long-term controlled human safety data is limited.

Common (most users)

  1. Increased appetite. Transient (30–60 minutes) via ghrelin-receptor activation.
  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. Modest cortisol / prolactin rise. Smaller than GHRP-6 but present; can cause lethargy or, rarely, mild prolactin-related effects at higher doses.
  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 or diagnostic single-dose.
  2. Theoretical tumor-growth risk. GH/IGF-1 elevation could accelerate a pre-existing malignancy; contraindicated with active cancer.

GHRP-2 trades a little selectivity for stronger GH release than ipamorelin. Users who are sensitive to cortisol or prolactin effects, or who want the cleanest long-term profile, often prefer ipamorelin; those prioritizing GH potency choose GHRP-2. Monitor IGF-1 and glucose with sustained use.

Does GHRP-2 interact with other drugs?

GHRP-2's interactions are mostly about 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-6, hexarelin, ipamorelin, MK-677). Redundant via the same receptor; no additive GH benefit.
  3. Direct human growth hormone (HGH). Combining is generally unnecessary — GHRP-2 stimulates endogenous GH, and exogenous HGH bypasses the feedback that makes secretagogues safer.
  4. No significant drug-drug pharmacokinetic interactions reported in published research.

How should GHRP-2 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: Store at 2–8°C; use within 28–30 days.
  3. Reconstitute with bacteriostatic water for injection (BAC water). Swirl gently — do not shake.
  4. Never freeze reconstituted solution.
  5. Protect from light. Store in original carton.
  6. Discard if cloudy, discolored, or contains particles.

What are the limitations of GHRP-2 research?

GHRP-2 is well characterized on the GH axis but not FDA-approved for therapy; its only regulatory approval is as a diagnostic agent (pralmorelin) in Japan. Body-composition and anti-aging claims rest on GH physiology and clinical practice, not controlled GHRP-2 trials. It is WADA-prohibited in sport.

GHRP-2 is not FDA-approved for any therapeutic use. Its GH-releasing potency is well documented — enough to support an approved diagnostic role in Japan — but that does not translate to approved treatment indications elsewhere.

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-2 itself. It is not cortisol-sparing, a real difference from ipamorelin.

The World Anti-Doping Agency prohibits GHRP-2 in sport under Section S2 (peptide hormones/secretagogues). Research-grade material is sold for laboratory use only and is not approved for human consumption.

Where to source GHRP-2

GHRP-2 is sold only as a research-grade peptide outside its diagnostic approval. The vendors highlighted below have been vetted for transparent third-party testing, traceable batch documentation, and verified discount codes.

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See all 26 verified vendors →

GHRP-2 FAQ

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

All three activate the same ghrelin/GH-secretagogue receptor (GHSR-1a). The differences are potency and selectivity. GHRP-2 is a more potent GH releaser than GHRP-6 and produces less appetite stimulation, but it still raises cortisol, prolactin, and ACTH modestly. Ipamorelin is the most selective of the group — GH-only, with essentially no cortisol or prolactin effect. GHRP-2 sits in the middle: stronger GH release than ipamorelin, cleaner than GHRP-6.

Is GHRP-2 approved for anything?

GHRP-2 (pralmorelin) is approved in Japan as a diagnostic agent for growth hormone deficiency — a single IV dose provokes a GH pulse that is measured to assess pituitary function. It is not FDA-approved for any therapeutic use in the United States and is sold elsewhere only as a research-grade peptide.

Does GHRP-2 raise cortisol?

Modestly, yes. Unlike ipamorelin (which is cortisol-sparing), GHRP-2 produces a small rise in cortisol, prolactin, and ACTH alongside GH. The effect is smaller than GHRP-6 but real — it is the main reason ipamorelin is often preferred for long-term use while GHRP-2 is favored where maximal GH release matters.

Will GHRP-2 make me hungry?

Yes, to a degree. GHRP-2 activates the ghrelin receptor, so appetite increases for a period after dosing — in a controlled study, healthy men ate about 36% more during a GHRP-2 infusion than with saline. The effect is real but generally less intense than GHRP-6. Bedtime dosing lets many users sleep through it.

Should I stack GHRP-2 with CJC-1295?

That is the standard pairing. GHRP-2 activates the ghrelin receptor while CJC-1295 activates the GHRH receptor; together they produce a larger GH pulse than either alone. Combining GHRP-2 with another ghrelin-receptor agonist (GHRP-6, hexarelin, ipamorelin, MK-677) is redundant.

How quickly does GHRP-2 work?

The GH pulse is immediate — peak GH typically occurs within about 15–60 minutes of a subcutaneous dose. Downstream effects (IGF-1 elevation, body-composition change) build over weeks of consistent dosing. The plasma half-life is short (roughly 30 minutes), so timing matters more than sustained blood levels.

Where can I buy GHRP-2?

GHRP-2 is sold by specialty research-peptide vendors. PP 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. 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/
  3. Laferrère B, Abraham C, Russell CD, Bowers CY, et al. Growth hormone releasing peptide-2 (GHRP-2), like ghrelin, increases food intake in healthy men. J Clin Endocrinol Metab. 2005;90(2):611-4. https://pubmed.ncbi.nlm.nih.gov/15699539/
  4. Chihara K, Kodama H, Kaji H, et al. A simple diagnostic test using GH-releasing peptide-2 in adult GH deficiency. Eur J Endocrinol. 2007;157(1):19-27. https://pubmed.ncbi.nlm.nih.gov/17609397/
  5. Mericq V, Cassorla F, Bowers CY, et al. Changes in appetite and body weight in response to long-term oral administration of the ghrelin agonist GHRP-2 in growth-hormone-deficient children. J Clin Endocrinol Metab. 2003;88(4):1476-81. https://pubmed.ncbi.nlm.nih.gov/14513874/
  6. 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.

J Clin Endocrinol Metab / PubMed · 2005Abstract open
Growth hormone releasing peptide-2 (GHRP-2), like ghrelin, increases food intake in healthy men →

Laferrère B, Abraham C, Russell CD, Bowers CY, et al.

A controlled human study showing that GHRP-2, like the natural hormone ghrelin, stimulates appetite: seven lean healthy men ate roughly 36% more during a GHRP-2 infusion than during saline. It is the clearest human demonstration that GHRP-2's ghrelin-receptor activity produces a real, measurable increase in food intake — not just GH release.

Eur J Endocrinol / PubMed · 2007Abstract open
A simple diagnostic test using GH-releasing peptide-2 in adult GH deficiency →

Chihara K, Kodama H, Kaji H, et al.

A validation of GHRP-2 as a provocative diagnostic test for adult growth-hormone deficiency: a single 100 mcg intravenous dose produces a reproducible GH peak within about an hour, with a defined cut-off distinguishing GH-deficient patients. This is the basis for GHRP-2's (pralmorelin's) approved diagnostic use in Japan and underlines how potent and reliable its GH-releasing action is.

J Clin Endocrinol Metab / PubMed · 2003Abstract open
Changes in appetite and body weight in response to long-term oral administration of the ghrelin agonist GHRP-2 in growth-hormone-deficient children →

Mericq V, Cassorla F, Bowers CY, et al.

A longer-term study in GH-deficient children showing that repeated GHRP-2 administration increases appetite and body weight over time — consistent with sustained ghrelin-receptor activity. It illustrates both the GH-axis effect and the appetite effect persisting with ongoing dosing rather than fading immediately.

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

Sigalos JT, Pastuszak AW

A clinical review of the growth-hormone-secretagogue class (GHRP-2, GHRP-6, ipamorelin, and others). It summarizes the shared ghrelin-receptor mechanism, contrasts the compounds' selectivity, and is candid about the limited long-term human safety data — a useful evidence-honest anchor for GHRP-2's real research standing versus its marketing.

Growth HormoneGHRPGHSR AgonistResearch-Grade

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For educational and research purposes only. Not medical advice. Not for human use.