A powerful hexapeptide that stimulates growth hormone release—used clinically in Japan for GH testing and studied for healing and anti-inflammatory effects.
Written by Michael Carroll — Owner, Director of Research · Reviewed by the Peptide Initiative Research Team · Editorial standards
Subcutaneous
Route
3 recommended
Sites
Once daily
Frequency
Preparation
Lyophilized GHRP-2 vial (typically 5-10 mg per vial)
Bacteriostatic water (0.9% benzyl alcohol saline solution)
Insulin syringe (29-31 gauge, 1 mL)
Alcohol swabs (70% isopropyl)
Sterile needle for drawing bacteriostatic water
Sterile needle for injection
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
If you receive a 5 mg vial and want 100 mcg (0.1 mg) per injection: Mix entire 5 mg vial with 50 mL bacteriostatic water. This creates a concentration of 0.1 mg/mL, so 1 mL (on the 100-mark of your insulin syringe) = 100 mcg.
Dose calculation
Formula: (Total mg in vial × 1000 mcg) ÷ mL of bacteriostatic water = mcg per mL. Example: (5 mg × 1000) ÷ 50 mL = 100 mcg/mL. To draw 100 mcg, pull to the 100-mark on a 1 mL (100 unit) insulin syringe.
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 in circular motion, allow to air dry (5-10 seconds)
Pinch a fold of skin and fat between thumb and forefinger to lift tissue away from muscle
Insert needle at 45-90 degree angle into the pinched fold (should be painless if done correctly)
Push plunger slowly and steadily to inject the full dose (takes 3-5 seconds)
Withdraw needle, release skin fold, and apply gentle pressure with fresh alcohol swab for 10 seconds
Pro tip
This peptide uses subcutaneous injection into fatty tissue (adipose layer between skin and muscle). 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
Administer on an empty stomach (2+ hours after meals, 30+ minutes before eating) to maximize GH response. [5][7] Fasting state enhances peptide efficacy.
With food?
Food intake, especially carbohydrates and amino acids, blunts the GH response. Maintain a gap of at least 2 hours post-meal for optimal effect.
Stacking notes
If combining with CJC-1295, space injections 15-30 minutes apart for synergistic effect. [10] Avoid injecting into the same body site within 48 hours.
Sample daily schedule
Morning (upon waking, fasted)
100-200 mcg injection
Site: Lower abdomen
Administer after 8+ hours of fasting for maximum GH response. Eat 30+ minutes after injection.
Pre-workout (if using twice daily)
100-200 mcg injection
Site: Outer thigh
Inject 30-60 minutes before resistance training on non-fasting days for enhanced muscle protein synthesis during workout.
Evening (optional third dose)
100-200 mcg injection
Site: Back of upper arm
Some advanced users inject before bed on fasted stomachs to capitalize on natural nighttime GH peaks. Not typical—reserve for intensive protocols.
Dosing tiers
Dose
1 mcg/kg/hour (continuous infusion) in research settings
Frequency
Continuous infusion
Duration
Study-defined (e.g. ~270 minutes in published trials)
Subcutaneous infusion dose used in controlled human GH-release/appetite studies; not an approved therapeutic regimen. [4]
Dose
100 mcg (0.1 mg) single bolus (diagnostic GH-stimulation test)
Frequency
Single administration
Duration
Single test; blood sampled at 0, 15, 30, 60 min
Japan-approved diagnostic dose (GHRP Kaken 100) for growth hormone deficiency; fixed 100 mcg IV bolus. A research GH-stimulation dose of 1 mcg/kg IV is also documented. [1]
Preservation
Before mixing
Keep lyophilized powder in freezer at -20°C or refrigerator at 4°C. Avoid repeated temperature fluctuations. Store in original vial protected from light and moisture.
After mixing
Refrigerate reconstituted solution at 2-8°C (36-46°F). Do NOT freeze reconstituted peptide. Use within 28 days of reconstitution. Keep vial capped and protected from light.
Shelf life after mixing
28 days
Signs of degradation
Discard the vial immediately if you notice any of these:
Solution becomes cloudy or discolored (indicates bacterial growth or oxidation)
Visible particles or crystals form in solution
Strong chemical odor emerges (suggests degradation)
Solution appears darker than initially prepared (oxidation from light or heat exposure)
Important
When to stop
Severe or persistent headaches that worsen despite dose reduction
Uncontrolled blood pressure elevation during dosing windows
Development of new joint pain or swelling that interferes with daily function
Signs of allergic reaction (rash, swelling, difficulty breathing)
Any signs of infection at injection site (increasing redness, warmth, drainage)
Planned surgery or acute hospitalization (discuss with medical team first)
This list is for educational purposes only and does not replace medical judgment. Always consult with a healthcare provider before starting, modifying, or stopping any peptide protocol. Pralmorelin is not FDA approved and should only be used under qualified medical supervision or within approved research settings.
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
Suzuki S, Ruike Y, Ishiwata K, et al. · 2022
This study investigated the properties and effects of Pralmorelin (GHRP-2), contributing to our understanding of its mechanism of action and potential therapeutic applications.
Onuki T, Hiroaki T, Sawano K, et al. · 2024
This study investigated the properties and effects of Pralmorelin (GHRP-2), contributing to our understanding of its mechanism of action and potential therapeutic applications.
Li Y, Yao L, Zhang C, et al. · 2025
This study investigated the properties and effects of Pralmorelin (GHRP-2), contributing to our understanding of its mechanism of action and potential therapeutic applications.
Laferrere B, Abraham C, Russell CD, Bowers CY · 2005
Kaken Pharmaceutical Co., Ltd.; Pharmaceuticals and Medical Devices Agency (PMDA) · 2025
Approved in Japan for the diagnosis of growth hormone deficiency as a single intravenous dose given in the fasting state — 2 mcg/kg for ages 4 to under 18 (100 mcg if body weight exceeds 50 kg), 100 mcg from age 18 — with serum GH sampled to 60 minutes. Listed adverse reactions include heat sensation (16.0%) and, at 0.1-5%, dizziness, facial flushing and headache. Contraindicated in pregnant women or women who may be pregnant; breastfeeding to be weighed against diagnostic benefit.
Fukuda I, Hizuka N, Muraoka T, Ichihara A · 2014
In Japan the GHRP-2 test is available and is recommended as a convenient and safe GH-stimulating test for diagnosing adult growth hormone deficiency, with a peak GH cut-off of 9 microg/L for severe deficiency.
Ghigo E, Arvat E, Muccioli G, Camanni F · 1997
Review of the GHRP class: GHRPs act via specific pituitary and hypothalamic receptors distinct from GHRH, counteract somatostatinergic activity, and release GH synergistically with GHRH. GHRP-6 was the first hexapeptide studied in humans, with GHRP-2 and hexarelin synthesised later. The GH-releasing effect does not depend on sex, is blunted by glucose and free fatty acids, and undergoes partial desensitization — more during continuous infusion, less during intermittent administration.
Root AW, Root MJ · 2002
Ghrelin and the synthetic GH secretagogues act through a G-protein-coupled receptor that stimulates phospholipase C, producing inositol 1,4,5-trisphosphate and diacylglycerol, raising cytosolic calcium and releasing GH; GHRH acts through a separate receptor via adenylyl cyclase/cAMP, and the two act synergistically in vivo. Secretagogues stimulate endogenous GH secretion, in contrast to recombinant human GH which supplies the hormone directly.
Bowers CY · 1993
GHRP-6, GHRP-1 and GHRP-2 are 6-7 amino-acid synthetic peptides; in humans the three were found to be increasingly more effective at releasing GH in that order, and all release GH more efficaciously than GHRH 1-44 NH2. Combined GHRP and GHRH administration releases GH synergistically.
Pihoker C, Middleton R, Reynolds GA, Bowers CY, Badger TM · 1995
GHRP-2 acts directly on pituitary somatotrophs to stimulate GH release. In 12 children given GHRH and GHRP-2 simultaneously the GH response was synergistic, matching observations previously reported in adults.
Pihoker C, Badger TM, Reynolds GA, Bowers CY · 1997
Fifteen short-stature children received intranasal GHRP-2 two to three times daily for 6 months, six of them for 18-24 months; administration was well tolerated and height velocity rose from 3.7 to 6.1 cm/year at 6 months.
Furuta S, Shimada O, Doi N, et al. · 2004
KP-102 / GHRP-2 / pralmorelin (CAS 158861-67-7) is the hexapeptide D-alanyl-3-(2-naphthyl)-D-alanyl-L-alanyl-L-tryptophyl-D-phenylalanyl-L-lysinamide dihydrochloride, which promotes GH release at both hypothalamic and pituitary sites. Across animal models it showed no serious general pharmacological effects on the central nervous, autonomic, respiratory, cardiovascular, digestive, renal or blood systems at GH-releasing doses.
Anderson SM, Shah N, Evans WS, Patrie JT, Bowers CY, Veldhuis JD · 2001
After bolus intravenous GHRP-2 the deconvolved GH secretory burst peaked within 8-13 minutes, and mean endogenous GH half-life was 17-18 minutes.
Higham CE, Jostel A, Trainer PJ · 2007
Weight-based GH replacement regimens led to significant side effects related to excess GH — arthralgias, headaches and peripheral edema — alongside IGF-I levels above the upper limit of the reference range.
Yuen KCJ, Heaney AP, Popovic V · 2016
GH and IGF-I may enhance tumorigenesis, metastasis and cell proliferation; studies of GH therapy in GH-deficient adults and childhood cancer survivors have not convincingly demonstrated an increased cancer risk, and the authors recommend individualised consideration, initiation no sooner than 2 years after remission, and close oncological surveillance.
Cohn L, Feller AG, Draper MW, Rudman IW, Rudman D · 1993
In elderly men treated with human growth hormone, carpal tunnel syndrome occurred in 10 of 62 treated men and gynaecomastia in 4, against 21 untreated controls. Both were associated with mean plasma IGF-I rising above 1.0 units/ml during treatment.
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