A ghrelin-receptor agonist that triggers a growth hormone pulse from the pituitary. Approved in Japan — but only as a single 100 μg intravenous dose for DIAGNOSING growth hormone deficiency, not as a treatment [6]. The one chronic human study, 8 months in 6 children, raised GH but left IGF-I unchanged [5].
Written by Michael Carroll — Owner, Director of Research · Reviewed by the Peptide Initiative Research Team · Editorial standards
Intravenous (approved diagnostic use)
Route
3 recommended
Sites
Single dose (approved diagnostic use)
Frequency
Preparation
Bacteriostatic water (BAC water)
Insulin syringe (29-31 gauge, 0.5-1mL)
Alcohol swabs
Sterile GHRP-2 vial (typically 5mg or 10mg)
Pro tip
Prepare all supplies on a clean surface before you begin. Having everything ready makes the process smoother and more sterile.
Mixing
Wash your hands thoroughly with soap and water. Gather all supplies on a clean, flat surface.
Remove the plastic cap from the peptide vial and wipe the rubber stopper with an alcohol swab. Let it air dry.
Draw the appropriate amount of bacteriostatic water into a sterile syringe.
Insert the needle into the vial at an angle, aiming at the inside wall of the vial. Slowly push the plunger to let the water trickle down the glass wall -- do NOT squirt directly onto the powder.
Once all water is added, gently swirl the vial in a slow circular motion. Never shake the vial, as this can damage the peptide bonds.
Continue swirling until the powder is completely dissolved and the solution is clear. If particles remain, let the vial sit for a few minutes and swirl again.
Label the vial with the date of reconstitution, the peptide name, and the concentration (e.g. 250mcg per 0.1mL).
Example calculation
5mg vial + 2.5mL BAC water = 2mg/mL (2000mcg/mL). For 200mcg dose, draw 0.1mL (10 units on insulin syringe).
Dose calculation
At 2000mcg/mL concentration: 0.05mL (5 units) = 100mcg, 0.1mL (10 units) = 200mcg, 0.15mL (15 units) = 300mcg
Pro tip
Always add the bacteriostatic water slowly, letting it run down the side of the vial. Never shake the vial -- swirl gently to avoid damaging the peptide.
Location
Site 01
Abdomen
Pinch the skin 2 inches from navel. Avoid the area directly around the belly button. Rotate between left and right sides.
Site 02
Outer Thigh
Middle third of the outer thigh. Keep at least 4 inches above the knee and below the hip. Alternate legs each injection.
Site 03
Upper Arm
Back or outer area of the upper arm. This site may require assistance from another person for proper technique.
Rotate between 3 sites to prevent tissue buildup and ensure consistent absorption.
Pro tip
Rotate your injection sites with each dose to prevent lipohypertrophy (buildup of fatty tissue). Keep a simple log of where you last injected.
Step by step
Clean injection site with alcohol swab and let dry completely
Pinch a fold of skin between thumb and forefinger
Insert needle at 45-90 degree angle into the pinched skin
Inject slowly and steadily
Remove needle and apply light pressure—do not rub the site
Pro tip
This peptide uses subcutaneous injection into fatty tissue. Inject at a 45-90 degree angle into pinched skin. Aspirate before injecting to ensure you haven't hit a blood vessel.
Timing
Optimal timing
Best time
Morning upon waking, post-workout, and before bed (on empty stomach)
With food?
Must be taken on an empty stomach—wait at least 30-60 minutes before eating. Food significantly blunts the GH release response.
Stacking notes
For maximum effect, combine with a GHRH peptide like CJC-1295 or Sermorelin at the same time. The synergy between GHRP and GHRH can amplify GH release by 5-10x compared to either alone.
Sample daily schedule
Fasted, in a clinical setting
100 mcg injection
Site: Slow intravenous injection
The approved schedule, and it is a single administration: dissolve the vial in 10 mL of saline immediately before use and inject slowly into a vein while the patient is fasting, then sample blood for growth hormone [6]. The morning / post-workout / bedtime three-a-day schedule previously published here came from no trial and no label.
Dosing tiers
Dose
100 mcg
Frequency
Single dose, once — this is a diagnostic test
Duration
One administration
The only dose of GHRP-2 approved by any regulator. Japan approves pralmorelin hydrochloride as GHRP Kaken 100 for diagnosing growth hormone deficiency: dissolve the vial in 10 mL of saline immediately before use and inject 100 μg slowly into a vein, fasted, for anyone 18 or over. Children aged 4 to under 18 get 2 μg/kg, capped at 100 μg above 50 kg. Blood is then sampled to see how much growth hormone the pituitary releases [6]. It is a one-off test. Nothing about this approval extends to repeated dosing or to injecting under the skin.
Dose
0.3 – 3 mcg/kg/day
Frequency
Once daily
Duration
2 months per dose level, 8 months in total
The only chronic subcutaneous dosing ever published, and it was in 6 growth-hormone-deficient children, not adults: 0.3, then 1.0, then 3.0 mcg/kg per day, each for 2 months [5]. Overnight GH rose with dose and growth velocity improved, but serum IGF-I and IGFBP-3 did not increase at any dose, and each injection's effect was brief. For a 75 kg adult these levels would be about 22 to 225 mcg a day — which is where the commonly quoted per-dose figures roughly land, though no trial has given them to an adult on that schedule.
Dose
100 – 300 mcg per dose
Frequency
1-3 times daily (community practice)
Duration
Undefined — no trial has run this schedule
Community-reported, not peer-reviewed and not on any label. This is the schedule most people asking about GHRP-2 mean, and it is worth being plain about what stands behind it: no human trial has dosed an adult subcutaneously one to three times daily at these amounts. The previous version of this page attributed the range to a study that does not contain it. What IS known at comparable exposures is that GHRP-2 raises food intake substantially — 33.5% above placebo at 1 mcg/kg/hour in 19 adults [7] — and that in the one chronic study IGF-I did not move [5].
Preservation
Before mixing
Store lyophilized (freeze-dried) powder refrigerated at 36-46°F (2-8°C) for several months. Can also be stored frozen at -4°F (-20°C) for longer-term storage up to 24 months. Keep in original packaging away from direct light.
After mixing
Refrigerate immediately at 36-46°F (2-8°C). Never freeze after reconstitution—this destroys the peptide. Store away from light. Discard after 28 days or if any degradation signs appear.
Shelf life after mixing
28 days
Signs of degradation
Discard the vial immediately if you notice any of these:
Cloudy or milky appearance (should be crystal clear)
Visible particles, floaters, or clumps in solution
Unusual color change from clear/colorless
Solution has been left at room temperature for extended periods
Important
When to stop
Signs of allergic reaction (rash, swelling, difficulty breathing)
Persistent carpal tunnel symptoms (numbness, tingling, weakness in hands)
Significant blood sugar elevation or difficulty managing diabetes
Pregnancy confirmed or suspected
Development of any new medical condition—consult your provider
Severe or persistent side effects not improving with dose reduction
Always consult with a healthcare provider before stopping or if you experience any concerning symptoms. This information is for educational purposes and should not replace professional medical advice.
Clean technique checklist
Wash hands thoroughly with soap and water before handling supplies
Swab vial tops and injection site with alcohol and let dry
Never touch the needle tip or allow it to contact non-sterile surfaces
Use a new syringe and needle for each injection
Dispose of used sharps in a proper sharps container
Store reconstituted peptides according to the storage instructions above
Published research
Norman C et al. · 2013
Testosterone and estradiol positively determine GH responses to GHRP-2 in older men, while BMI negatively affects pulsatile GH secretion during GHRP-2 infusion.
Veldhuis JD et al. · 2009
GHRP-2 was more stimulatory than GHRH for GH release in women. Age and estrogen status together explained 60% of the variability in GHRP-2 effectiveness.
Veldhuis JD et al. · 2009
L-arginine combined with GHRP-2 provides a robust GH stimulus that remains effective even during short-term hormone deficiency, unaffected by visceral fat or IGF-1 levels.
Veldhuis JD et al. · 2009
Abdominal visceral fat is a dominant negative predictor of both GHRH and GHRP-2 effectiveness. Fasting IGF-I concentration positively correlates with secretagogue efficacy.
Mericq V, Cassorla F, Salazar T, Avila A, Iniguez G, Bowers CY, Merriam GR · 1998
The only chronic human study of GHRP-2, and it is small. Six prepubertal children with growth hormone deficiency received escalating subcutaneous doses of 0.3, then 1.0, then 3.0 mcg/kg per day, each for a 2-month period, followed by a fourth period combining 3 mcg/kg GHRP-2 with 3 mcg/kg GHRH. Overnight GH secretion rose dose-wise and growth velocity was higher during treatment than before or after. But serum IGF-I and IGFBP-3 DID NOT INCREASE, and the GH profiles showed the effect of each injection was brief with little influence on secretion later in the night. No side effects or toxicities were observed in those 6 children. The authors' own conclusion is that formulations with a longer duration of action would be needed for GHRP-2 to be useful as therapy.
Kaken Pharmaceutical Co., Ltd.; Pharmaceuticals and Medical Devices Agency (PMDA), Japan · 2025
The only regulatory approval this compound has anywhere, and it is for a diagnostic test rather than a treatment. The approved indication is the diagnosis of growth hormone deficiency (成長ホルモン分泌不全症の診断). The dose is a SINGLE slow intravenous injection given fasted, after dissolving the vial in 10 mL of saline: 100 μg for anyone aged 18 or over, and 2 μg per kg of body weight for ages 4 to under 18, capped at 100 μg for children over 50 kg. Adverse reactions listed on the label are abdominal rumbling, leukocytosis, a feeling of warmth, low blood pressure, nausea, gastric discomfort, abdominal distension, drowsiness and a runny nose. Nothing on this label covers repeated dosing, subcutaneous injection, or use for body composition.
Laferrère B, Hart AB, Bowers CY · 2006
The clearest measurement of what GHRP-2 does to appetite in people. Nineteen healthy weight-stable adults (10 lean, 9 obese) each received, double-blind and in random order, a subcutaneous infusion of GHRP-2 at 1 mcg/kg/hour, 0.1 mcg/kg/hour, or placebo over 270 minutes, then ate freely at a buffet lunch. Food intake rose 10.2 ± 3.9% at the low rate (p=0.011) and 33.5 ± 5.8% at the high rate (p<0.001) against placebo, dose-dependently. Obesity did not blunt the effect — obese participants responded as much as lean ones, in both food intake and GH. Appetite ratings before the meal were higher while fullness afterwards was the same, so the drive is to start eating rather than to stop later.
Van den Berghe G, Baxter RC, Weekers F, et al. · 2002
Thirty-three critically ill men were randomised to 5 days of placebo (n=7), GHRP-2 alone at 1 mcg/kg/hour (n=9), GHRP-2 plus TRH (n=9), or GHRP-2 plus TRH plus pulsatile GnRH (n=8). GHRP-2 alone reactivated GH secretion and normalised IGF-I, IGFBP-3 and the acid-labile subunit. It did not deliver the metabolic benefit: ureagenesis fell with the two combinations (p=0.01 and p=0.009) but NOT with GHRP-2 alone, and osteocalcin rose only with the triple combination. By day 5, serum lactate and white cell count were increased by GHRP-2 infused alone and with TRH, but not by the triple combination. Restoring one hormonal axis in isolation was not enough, and carried signals the fuller replacement did not.
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