GHRP-2
Growth-hormone-releasing peptide · ghrelin-receptor (GHS-R1a) agonist · Japanese diagnostic agent
GHRP-2 is a six-amino-acid peptide, approved in Japan as a pituitary test, that fires your own growth hormone (GH). People run it for GH pulses, recovery and appetite on a bulk. In human study it released more GH than a maximal dose of growth-hormone-releasing hormone.
At a glance
- Dose
- 100–300 mcg per injection; 100 mcg to start
- How often
- 1–3 times a day, starting once daily
- How
- A small injection under the skin
- When
- Bedtime on an empty stomach; extra doses at least 3 hours apart
- Cycle
- 8–12 weeks on, then a 4–8 week break
The 30-second versionEverything on this page, fast
Strong GH pulse · Your own GH · Appetite for a bulk · Approved test in Japan
The growth-hormone-releasing peptide (GHRP) that Japan approved as a diagnostic. GHRP-2 works the ghrelin receptor to fire your own GH pulse. In human study it released more GH than a maximal GHRH dose, and it raised food intake about 35.9%, the appetite people use on a bulk.
The basics
- A synthetic six-amino-acid peptide that signals the pituitary to release growth hormone through the ghrelin receptor (GHS-R1a).
- Approved as a diagnostic test in Japan ('GHRP Kaken 100'), the GHRP with the most regulatory standing.
Why people use it
- A powerful GH trigger. In human study it released more GH than a maximal dose of GHRH, one of the strongest GHRPs per microgram.
- Your own GH, not injected. It fires the body's natural GH pulse through the ghrelin receptor, so feedback and rhythm stay intact.
- The GHRP with an approval. Japan approved it as a diagnostic ('GHRP Kaken 100'), more real-world standing than any other peptide in the family.
- Stacks with a GHRH analog. Pair it with the GHRH arm, most often CJC-1295, for a combined pulse bigger than either alone.
Stacks well with
- CJC-1295 is the classic pairing. GHRP-2 works the ghrelin arm and CJC-1295 the GHRH arm, a synergy shown in human pharmacology.
- BPC-157 + TB-500 as the recovery backdrop. GHRP-2 adds a systemic anabolic signal on top of the local repair those two drive.
Good to know
- Expect real hunger 30–60 minutes after a dose (about 35.9% more food intake in study). A drawback when cutting, useful fuel on a bulk.
- It raises cortisol, ACTH and prolactin along with GH, a class effect, so people keep cycles short and check those markers on longer runs.
What it does
The GH-releasing peptide with the most regulatory standing. Here's what draws people to it.
- A powerful growth-hormone triggerIn 8 healthy young men, GHRP-2 drew about triple the GH response of the same dose of GHRH.
- Raise your own GH, not inject itIn 17 older adults, a 30-day infusion under the skin kept GH pulses over 1.8-fold above saline and IGF-1 raised.
- The GHRP with an approvalIn the Japanese validation study, 77 healthy people averaged an 84.6 ng/mL GH peak, against 1.36 in 58 GH-deficient patients.
- Lifted IGF-1 within a dayIn critically ill adults in intensive care, a 21-hour GHRP-2 infusion raised GH 4–6-fold and IGF-1 61% within 24 hours.
- Appetite that fuels a bulkIn 7 lean men, a 270-minute infusion under the skin made every one eat more at a buffet, by 12–95%.
Sources:PMID 7586605PMID 15126555PMID 17609397PMID 9024260PMID 15699539
How it works
Fires your own GH pulse. GHRP-2 switches on GHS-R1a, the receptor for ghrelin, the body's hunger hormone. In direct human study it released more growth hormone (GH) than the maximal effect of GHRH (growth-hormone-releasing hormone).
Works a second doorway. GHRH analogs such as sermorelin and CJC-1295 use a different receptor. In humans, a ghrelin-receptor agonist plus GHRH releases more GH than either alone. Two secretagogues on the ghrelin receptor do not add the same way.
Raises other hormones too. Alongside GH it releases ACTH (the adrenal-driving hormone), cortisol and prolactin, a class effect of growth-hormone-releasing peptides (GHRPs).
Drives appetite. An infusion under the skin in healthy men raised food intake about 36% and lifted pre-meal hunger.
How to dose it
Most people run GHRP-2 as a small injection under the skin (SC), at bedtime and on an empty stomach.
Dose tiersMost people run 100–300 mcg per injection, 1–3× daily on an empty stomach.
- Entry / sensitivity check:
- 100 mcg once daily at bedtime, to check tolerance before adding doses. The on-page calculator default.
- Standard:
- 100–200 mcg 1–2× daily. The most common range, at bedtime plus an optional fasted morning or pre-workout dose.
- High-frequency:
- 100–300 mcg up to 3× daily for active recovery or loading. Appetite, cortisol and prolactin climb with frequency, so people keep it short.
- Food window:
- Food waits at least 30–60 minutes after, since fat and carbs blunt the pulse. The stricter habit adds a 2-hour fast before.
How to injectIt goes into the fat under the skin. Rotate sites to avoid fatty lumps.
- Injection site:
- Belly (2–3 cm from the navel), love-handle area or outer thigh. Rotate sites across the day's doses.
- Measuring the dose:
- At 5 mg in 2 mL, 100 mcg takes 4 units, 200 mcg takes 8 units and 300 mcg takes 12 units on U-100 syringes. The calculator covers other vials.
- Time of day:
- Bedtime first, riding the largest GH pulse in early deep sleep. A fasted morning or pre-workout dose is the usual second, ≥ 3 hours apart.
- Appetite alert:
- Food intake rose ~35.9% in a controlled human study (Laferrère 2005). Hunger hits 30–60 minutes after, so make that meal protein-forward.
Cycle and breaksPeople run it in cycles.
- Standard cycle:
- 8–12 weeks of daily use, then a break. Some use a 5-on / 2-off weekly pattern inside a longer cycle to keep the response from fading.
- Washout:
- 4–8 week break between cycles. On longer runs, people check cortisol and prolactin during the break.
Mixing the vialThe default is a 5 mg vial with 2 mL of bacteriostatic water.
- Mixing:
- That makes 2,500 mcg per mL. On a U-100 syringe, 100 mcg takes 4 units, 150 mcg takes 6 units, 200 mcg takes 8 units, 300 mcg takes 12 units.
Best time to take it
Implied best time
Bedtime (empty stomach)
Most people inject GHRP-2 at bedtime on an empty stomach, with optional extra fasted doses in the morning or pre-workout.
- The body's largest natural GH pulse fires in early deep sleep. A bedtime dose stacks GHRP-2's pulse on top of it.
- A meal raises insulin and somatostatin, GH's off-switch, which blunt the pulse. People dose ~2 hours clear of eating and hold food 30–60 min after.
- Some pulse it 2–3× daily, all fasted, ≥3 hours apart, with bedtime as the anchor. Hunger hits 30–60 minutes after, so plan the meal.
Sources:PMID 15699539
What to stack it with
Partners work the GHRH arm or tissue repair. Ipamorelin, GHRP-6 and Hexarelin share GHRP-2's receptor, so adding them is redundant.
GHRP-2 + CJC-1295The classic pairing, for a bigger GH pulse.
- Why it works:
- CJC-1295 works the GHRH receptor. In humans, GHRH plus a ghrelin-receptor agonist releases more GH than the sum of each.
- The protocol:
- GHRP-2 100–200 mcg + CJC-1295 100–200 mcg SC, co-injected 1–2× daily, bedtime preferred. CJC-1295 with DAC (drug-affinity complex) lasts days, so some inject it 1–2× weekly and keep GHRP-2 daily.
- Outcome:
- For maximum GH output, body composition and recovery.
GHRP-2 + Sermorelin or TesamorelinOther GHRH partners, same synergy, different timing.
- Why it works:
- Sermorelin is short-acting, so both go in together. Tesamorelin, FDA-approved for HIV-associated lipodystrophy, is more forgiving.
- The protocol:
- GHRP-2 100–200 mcg SC + sermorelin 200–500 mcg SC, co-injected on one schedule. Or tesamorelin 1–2 mg SC daily (its studied dose) with standard-range GHRP-2.
- Outcome:
- Sermorelin is the cheaper, shorter-acting pick. Tesamorelin has the richest clinical data of any GHRH analog.
GHRP-2 + BPC-157 + TB-500A recovery stack with a GH backdrop.
- Why it works:
- BPC-157 grows new vessels and TB-500 moves repair cells in. GHRP-2 adds a body-wide GH signal for collagen and protein build-up.
- The protocol:
- GHRP-2 100–200 mcg SC 1–2× daily. BPC-157 250–500 mcg SC once daily near the injury. TB-500 runs higher the first 2–4 weeks, then lower. Separate syringes or nearby sites.
- Outcome:
- For soft-tissue injury, surgery or heavy training. Extra hunger feeds repair.
Sources:PMID 11238504PMID 15699539
Support nutrients
These widen the pulse, offset side costs and feed growth.
Widen the GH pulseSomatostatin is GH's off-switch. These two blunt it.
- L-Arginine:
- 3–6 g on an empty stomach 30–60 min before the injection. Start at 3 g, since more upsets some stomachs.
- Alpha-GPC:
- 300–600 mg ~30 min before injection, pre-bed or pre-workout. It raises acetylcholine, which blunts somatostatin.
Offset the side costsGHRP-2 also raises glucose, cortisol, prolactin and appetite.
- Berberine 500 mg:
- With the protein meal ~30–60 min after injection. It offsets GH's glucose rise without blunting the pulse.
- Alpha-lipoic acid (ALA) 600 mg:
- With the same meal, for insulin sensitivity.
- Cortisol and prolactin:
- People run short cycles (8–12 weeks), skip it during poor sleep, overtraining or stress, and check both on longer runs. Ipamorelin is the cleaner option.
- Appetite management:
- Food intake rose ~35.9% in healthy men. People steer it into leucine-rich protein (1.6–2.0 g protein/kg/day total).
Feed the growth signalIGF-1 (insulin-like growth factor 1), GH's downstream messenger, drives protein synthesis. These supply the raw material.
- Dietary protein 1.6–2.0 g/kg/day:
- For muscle and connective tissue. One leucine-rich serving (25–40 g) lands 30–90 minutes after injection, when hunger peaks.
- ZMA (zinc + magnesium + B6) before bed:
- Zinc 25–30 mg + magnesium glycinate 300–400 mg + B6, 30 min before the bedtime injection. Low zinc tracks with lower IGF-1; magnesium supports deep sleep.
- Vitamin D 2,000–5,000 IU/day:
- Low levels go with blunted GH responses. People aim for a blood vitamin D level (25-OH-D) of ≥40 ng/mL.
Sources:PMID 15699539PMID 9285939
Dose calculator
Reconstitution calculator
Calculated for a 1 mL U-100 insulin syringe (100 units/mL).
Units per dose
4 units
Draw this many units on a U-100 syringe
Each unit holds 25 mcg
- Volume per dose
- 0.04 mL
- Doses per vial
- 50
- Concentration
- 2.5 mg/mL
One vial lasts
- Daily
- 50 days
- Every other day
- 100 days
- 5×/week
- 70 days
Research use only. Not for human consumption. Outputs are reference values based on research literature. Verify all measurements independently.
Side effects and what to watch
What people notice. Hunger. In a controlled human infusion study, food intake rose about 36% and pre-meal hunger climbed.
Hormones beyond GH. It raises ACTH, cortisol and prolactin along with GH, a class effect of GHRPs. In human study the ACTH and cortisol rise was comparable to CRH, the brain's stress-axis trigger. The prolactin rise was smaller than from TRH, a thyroid-signaling hormone.
How people handle it. Short cycles, and a check of cortisol and prolactin on longer runs.
Competing? It is banned in tested sport at all times.
Sources:PMID 9285939PMID 15699539
Common questions
How is GHRP-2 dosed?
Most people run 100–300 mcg per injection, 1–3× daily, as a small injection under the skin. Many start at 100 mcg once daily at bedtime, on an empty stomach.
Do I need to cycle GHRP-2?
Most people do. A typical run is 8–12 weeks of daily use, then a 4–8 week break.
How is GHRP-2 different from GHRP-6, hexarelin and ipamorelin?
All four work the ghrelin receptor, so pairing them is redundant. GHRP-2 is commonly described as a stronger GH releaser per microgram than GHRP-6 and holds the Japanese approval. Ipamorelin is the cleaner pick on cortisol and prolactin.
What does GHRP-2 stack with?
A GHRH analog. CJC-1295 is the classic partner, both at 100–200 mcg co-injected at bedtime. They work separate receptors, so together they release more GH than either alone.
Does GHRP-2 raise cortisol?
Yes, along with ACTH and prolactin, a class effect of GH-releasing peptides. People keep cycles short and check those markers on longer runs.
What is GHRP-2's half-life?
About 33 minutes, after a single 1 µg/kg intravenous (IV) dose in a Phase I study in children.
Deep dive
Doses used in studies · Molecular identity · References
10From the researchDoses used in studies
These are the doses used in the published human studies, from the GH test, a half-life study in children and an appetite infusion in men.
| Dose | Route | Model | Outcome | Sources: |
|---|---|---|---|---|
| Not stated in this source (the 100 µg of "GHRP Kaken 100" needs a Japanese label) | Not stated in this source (the profile lists subcutaneous, buccal, oral and depot, never IV) | Human (GH-deficiency diagnosis) | As of this 2004 profile, AWAITING approval in Japan as a diagnostic agent for hypothalamo-pituitary function, with launch planned for 2004. The profile does not establish approval, and the 100 µg IV figure and the trade name need a Japanese label source | PMID 15230633 |
| 1 µg/kg | IV bolus | Human (10 prepubertal short-stature children) | Peak GH ~50.7 ng/mL; elimination half-life ~33 min (Phase I PK) | PMID 9543135 |
| 1 µg/kg/h × 270 min | SC infusion | Human (7 lean healthy men) | Food intake +35.9%; higher pre-meal hunger ratings | PMID 15699539 |
11ChemistryMolecular identity
- Molecular weight
- 818.0 g/mol (free base)
- Molecular formula
- C45H55N9O6
- Monoisotopic mass
- 817.43 Da (free base)
- CAS / UNII
- 158861-67-7 · E6S6E1F19M
- Sequence (6 AA)
- D-Ala-D-2-Nal-Ala-Trp-D-Phe-Lys-NH₂PubChem CID 6918245
- Structure / class
- Synthetic GHRP-class hexapeptide (GHS-R1a agonist)Research literature
- Molecular target
- GHS-R1a (ghrelin receptor) on pituitary somatotrophsResearch literature
- Regulatory status
- Diagnostic-approved in Japan (GHRP Kaken 100); not therapeutic anywhere · WADA S2.2.4PMID 15230633 / WADA
12Primary sourcesReferences
- PubChem CID 6918245PubChem, Pralmorelin / GHRP-2 free base (CID 6918245)
- PMID 15230633Pralmorelin (KP-102, GPA-748) Adis R&D profile 2004. Japanese diagnostic approval, discontinued US development (Drugs R D)
- PMID 9285939Arvat et al. 1997. GHRP-2 & hexarelin GH potency and ACTH/cortisol/prolactin co-release in humans (Peptides)
- PMID 11238504Arvat et al. 2001. Ghrelin/GHS-R agonism, GHRH synergy, distinct receptors (JCEM)
- PMID 9543135Pihoker et al. 1998. Phase I pharmacokinetics of GHRP-2 in children, ~33 min elimination half-life (JCEM)
- PMID 15699539Laferrère et al. 2005. GHRP-2 increases food intake (+35.9%) in healthy men (JCEM)
- WADA Prohibited List S2.2.4WADA Prohibited List, S2.2.4 GH-Releasing Peptides (GHRP-2/pralmorelin named)
- PMID 7586605Tiulpakov et al. 1995. GHRP-2 and GHRH alone and together in 8 healthy men (Clin Endocrinol)
- PMID 15126555Bowers et al. 2004. 30-day continuous GHRP-2 infusion sustains GH pulses and IGF-1 in older adults (JCEM)
- PMID 17609397Chihara et al. 2007. GHRP-2 test validated for adult GH deficiency in 77 healthy subjects and 58 patients (Eur J Endocrinol)
- PMID 9024260Van den Berghe et al. 1997. Continuous GHRP-2 and GHRH infusion in critical illness (JCEM)
Reviewed by Ki Researcher Team · Research use only · Not medical advice · Updated 2026-10-19