Growth hormone
A six-amino-acid peptide that triggers growth hormone release — used clinically in Japan to test GH function, and studied for healing effects.
Start here
Pralmorelin (GHRP-2) is a lab-made peptide of six amino acids that prompts the body to release its own growth hormone. In Japan it is used clinically as a diagnostic test for growth hormone deficiency. Elsewhere it has only limited human trial evidence and is a research compound, not an approved medicine.
Pralmorelin (GHRP-2) is a synthetic peptide that acts like a key fitting into specific receptors in your pituitary (the master hormone gland at the base of the brain) gland. When injected, it unlocks the signal for your body to release growth hormone—one of the most powerful anabolic (muscle-building) and healing hormones your body produces. Think of it as a megaphone amplifying your pituitary's existing ability to release GH. It's not giving you GH directly; it's stimulating your own body to make and release more. 78 This is why response varies—your body has to be capable of responding to the signal.
Pralmorelin is used to boost the body's own growth hormone output in growth hormone deficiency and in the natural decline that comes with age. Because it prompts your own gland to release the hormone in its normal bursts, it preserves the natural rhythm of release — an advantage over injecting growth hormone directly.
GHRP-2 is a hexapeptide (a chain of 6 amino acids). It attaches to ghrelin (the hunger hormone) receptors (also called growth hormone secretagogue receptors, or GHS-R1a) on somatotrophs, the cells in the front part of the pituitary (the master hormone gland at the base of the brain) gland that make growth hormone. Attaching switches on signals inside the cell (mainly IP3/DAG and a rise in calcium) that excite the cell and make it release packets of growth hormone into the blood. 8 GHRP-2 also blocks somatostatin (a hormone that holds growth hormone back). So it boosts growth hormone two ways: it pushes release directly and it removes the brake. 78 Growth hormone (GH) levels peak 15-30 minutes after injection, and GH itself has a half-life (how long it stays active in your body) in the blood (the time for half of it to clear) of about 20 minutes. 13 GHRP-2's six-amino-acid structure (D-Ala-D-β-Nal-Ala-Trp-D-Phe-Lys-NH2) includes three D-amino acids (unnatural mirror-image forms). These protect it from being broken down by enzymes in the body, so it survives long enough to reach the pituitary. 12 Recent research suggests it may also calm inflammation by changing how macrophages (immune cleanup cells) behave. That could explain the healing seen in soft tissue injuries beyond simple GH-driven muscle building (anabolism). 3
Evidence check
Very few human studies
Only a handful of small human studies exist. Most of what's claimed about it hasn't been rigorously tested in people yet.
Every numbered marker on this page links to one of the 16 sources at the bottom.
Muscle & Performance Enhancement
GHRP-2 directly stimulates GH release, amplifying training response and accelerating lean mass development. Athletes and serious lifters report faster recovery, improved workout capacity, and visible lean mass gains over 4-6 week cycles.
Injury Recovery & Healing
Research suggests GHRP-2 reduces inflammation and supports tissue repair through anti-inflammatory mechanisms. Those recovering from sports injuries, surgical procedures, or chronic soft tissue issues report faster healing timelines.
Diagnostic Clinical Use
GHRP-2 is the gold-standard diagnostic peptide for assessing growth hormone deficiency. A single injection reliably stimulates GH release (or fails to in GH-deficient patients), enabling physicians to diagnose GH axis disorders with high accuracy.
The most-asked question
The research-reported range is 1 mcg/kg/hour, once daily. Studies used different doses for different situations — find yours:
Research on GH secretion and appetite
1 mcg/kg/hour (slow, steady drip) in research settings
Subcutaneous (under the skin) infusion dose used in controlled human GH-release/appetite studies; not an approved therapeutic regimen. 4
Diagnosis of growth hormone deficiency
100 mcg (0.1 mg) as a single quick dose (bolus), used in a test of how well the body releases growth hormone
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
The ceiling: 300 mcg per injection, up to 3 times daily (900 mcg/day maximum)
Reconstitution, in plain words
Peptides usually arrive as a freeze-dried powder in a small vial. “Reconstitution” just means adding sterile water back in so you can measure a dose. Here's how it works for Pralmorelin (GHRP-2):
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.
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.
Three quick questions — your vial, your water, your dose — and it tells you the exact syringe mark. “Find dose amount” is preloaded with Pralmorelin (GHRP-2)'s recorded schedule.
Injection sites & technique
Injection under the skin (into the fatty layer between the skin and muscle)
Timing
Administer on an empty stomach (2+ hours after meals, 30+ minutes before eating) to maximize GH response. 57 Fasting state enhances peptide efficacy.
Food intake, especially carbohydrates and amino acids, blunts the GH response. Maintain a gap of at least 2 hours post-meal for optimal effect.
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.
The honest list
These show up most often. They usually fade as your body adjusts.
Mild to moderate warmth and redness in face/neck area occurring 5-15 minutes post-injection. 5 Resolves within 30-60 minutes. Results from vasodilation (widening blood vessels) triggered by rapid GH release.
What to do Completely benign. If severe, reduce dose slightly or slow injection speed. Stays hydrated and avoid hot beverages immediately post-injection.
Mild headache 1-2 hours post-injection, typically lasting 1-4 hours. 5 Usually mild and self-limited. More common with higher doses or on empty stomach.
What to do Take over-the-counter pain reliever (acetaminophen or ibuprofen) if bothersome. Stay hydrated. Usually resolves with continued use as body adjusts.
GHRP-2 stimulates hunger signals, 4 though less pronounced than GHRP-6. Typically mild appetite increase for 2-4 hours post-injection. Manageable with diet discipline.
What to do Eat protein-rich snacks post-injection if needed. Timing injections before meals can help. If appetite becomes disruptive, reduce dose or switch to less appetite-stimulating alternatives like Ipamorelin.
Brief episodes of dizziness (minutes to hours) related to rapid blood pressure or fluid shifts. 5 Usually mild and self-resolving. More common in dehydrated individuals.
What to do Ensure adequate hydration before and after injection. Sit or lie down if dizziness occurs. Avoid sudden position changes post-injection. Rare, disappears with repeated use.
Worth knowing about, but most people never see these.
Temporary tingling or mild numbness in hands/fingers (hours to days). Caused by rapid GH-induced fluid retention in tissue spaces, not true carpal tunnel. 1416 Resolves without intervention.
What to do Typically self-limiting. Reduce dose if symptoms persist. Ensure adequate sleep and joint support. Very rare; discontinue if severe and persistent.
Transient mild aches in joints or muscles (24-48 hours post-injection). Related to GH-induced fluid shifts and metabolic changes. 14 Not serious muscle damage.
What to do Use ice or heat as needed. Over-the-counter pain relievers help. Stretching and light activity usually improve symptoms. Completely reversible.
Variable sleep effects—some report deeper sleep, others report insomnia if injected too close to bedtime. Individual response varies considerably.
What to do Avoid injections within 4 hours of bedtime. If injecting at night, move to morning protocol. Usually stabilizes after first week of use.
Rare, but if any of these happen, stop and contact a medical professional.
Extremely rare with synthetic peptides. Would include rapid onset of difficulty breathing, throat swelling, severe rash, and shock within minutes of injection.
What to do SEEK IMMEDIATE MEDICAL ATTENTION (call 911). Have epinephrine auto-injector (EpiPen) available if history of peptide allergies. Stop use and inform physician.
Week by week
Is it right for you?
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.
Synergistic GH stimulus via dual mechanism (GHRH + GHRP). Often combined for enhanced results. Space injections 15-30 minutes apart.
Both GHRPs work through similar mechanism. Combining offers minimal additional benefit and increases side effects. Avoid stacking.
Both are GHRPs with overlapping function. GHRP-2 is more potent; stacking with GHRP-6 is redundant and increases appetite effects unnecessarily.
Synergistic effect on muscle protein synthesis. Safe to combine; enhances anabolic (muscle-building) response. Ensure both are used responsibly.
If you're serious about lean muscle gains and recovery, pralmorelin directly stimulates GH release—one of the body's most powerful anabolic (muscle-building) hormones. 79 Most athletes in research settings use 100-200 mcg for faster muscle repair and improved performance.
Recent animal studies show GHRP-2 reduces inflammation and speeds tendon-bone healing. 3 If you're dealing with sports injuries, rotator cuff issues, or fractures, this peptide's anti-inflammatory profile may accelerate recovery when combined with proper rehab.
If your doctor suspects growth hormone deficiency, pralmorelin is the gold-standard diagnostic tool in Japan and many countries. A single injection stimulates GH release, allowing physicians to assess your pituitary (the master hormone gland at the base of the brain) function safely and accurately 156.
Pralmorelin is one of the most extensively studied GHRPs worldwide. If you're exploring peptide protocols and understand research-grade products, this is a powerful tool for understanding how your GH axis responds to stimulation.
Pralmorelin (GHRP-2) has been safely used in diagnostic settings in Japan for decades and is well-tolerated in most individuals when used at appropriate doses. 5611 The peptide is synthetic and chemically stable, with low immunogenicity risk. However, it is NOT FDA approved and should only be used under medical supervision or within research protocols. Long-term safety data in healthy humans is limited.
Most safety evidence comes from short-term diagnostic studies (single or few-dose protocols) and animal research. Long-term use in therapeutic dosing is not extensively studied in humans. Users should be aware they are using a research compound with limited long-term safety profiling.
Keeping it good
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.
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.
Not our opinion — the published record
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.
Suzuki S, Ruike Y, Ishiwata 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.
Onuki T, Hiroaki T, Sawano K, 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.
Li Y, Yao L, Zhang C, et al.
2005
Laferrere B, Abraham C, Russell CD, Bowers CY
2025
Approved in Japan for diagnosing growth hormone deficiency, as a single dose through a vein given while fasting: 2 mcg/kg for ages 4 to under 18 (100 mcg if body weight exceeds 50 kg), and 100 mcg from age 18. Growth hormone is then measured in the blood for up to 60 minutes. Listed side effects include a feeling of heat (16.0%) and, at 0.1-5%, dizziness, facial flushing and headache. Must not be used in pregnant women or women who may be pregnant. For women who are breastfeeding, doctors must weigh breastfeeding against the benefit of the test.
Kaken Pharmaceutical Co., Ltd.; Pharmaceuticals and Medical Devices Agency (PMDA)
2014
In Japan the GHRP-2 test is available and is recommended as a convenient and safe test (it triggers growth hormone release) for diagnosing growth hormone deficiency in adults, with a peak GH level cut-off of 9 microg/L marking severe deficiency.
Fukuda I, Hizuka N, Muraoka T, Ichihara A
1997
Review of the GHRP class (growth hormone-releasing peptides): GHRPs act on specific receptors in the pituitary and hypothalamus that are different from the GHRH receptor, work against somatostatin (a hormone that holds growth hormone back), and release GH together with GHRH in a way that adds up to more than either alone (synergistically). GHRP-6 was the first hexapeptide (6-amino-acid peptide) studied in humans, with GHRP-2 and hexarelin made later. The GH-releasing effect does not depend on sex, is weakened by glucose and free fatty acids, and partly wears off (desensitization), more during continuous infusion and less during intermittent dosing.
Ghigo E, Arvat E, Muccioli G, Camanni F
2002
Ghrelin and the synthetic GH secretagogues (drugs that trigger GH release) act through a G-protein-coupled receptor (a cell-surface receptor that passes signals inward). It stimulates phospholipase C (an enzyme), producing inositol 1,4,5-trisphosphate and diacylglycerol (two signaling molecules), which raise calcium inside the cell and release GH. GHRH acts through a separate receptor via adenylyl cyclase/cAMP (another signaling route), and the two work together (synergistically) in the living body. Secretagogues stimulate the body's own GH release, in contrast to recombinant human GH (lab-made GH), which supplies the hormone directly.
Root AW, Root MJ
1993
GHRP-6, GHRP-1 and GHRP-2 are synthetic peptides 6-7 amino acids long. In humans the three were found to be increasingly more effective at releasing GH in that order, and all release GH more effectively than GHRH 1-44 NH2 (the body's own GH-releasing hormone). Giving GHRP and GHRH together releases GH synergistically (more than either alone).
Bowers CY
If this isn't the right fit
Your questions
No—they're completely different. GHRP-2 is a peptide that STIMULATES your body to release its own growth hormone. HGH is synthetic growth hormone itself (recombinant DNA-derived). 8 GHRP-2 works by signaling your pituitary (the master hormone gland at the base of the brain), while HGH directly replaces the hormone. Think of GHRP-2 as a performance coach telling your body to produce more GH; HGH is like directly giving your body the hormone it needs.
GHRP-2 and GHRP-6 are similar (both hexapeptide GHRPs), but GHRP-2 is considered more potent at stimulating GH release and produces less appetite stimulation. GHRP-6 was developed first and is generally weaker; 79 it also tends to trigger stronger hunger signals. If you're choosing between them, GHRP-2 is typically preferred for GH stimulation, while GHRP-6 might be chosen if appetite boost is desired (rare scenario).
Yes, and the two work well together and are very common in research protocols. GHRP-2 acts on one type of receptor (GHS-R, the ghrelin (the hunger hormone) receptor), while CJC-1295 acts on a different one (GHRH-R, the receptor for the brain's own GH-releasing signal). Together they boost GH release more than either alone. 810 Space injections 15-30 minutes apart for best effect. This pairing is considered one of the most effective natural GH-stimulation stacks available.
Not on its own. GHRP-2 stimulates growth hormone, which is anabolic (muscle-building) but relatively mild compared to testosterone or synthetic steroids. GH primarily supports recovery, fat loss, and lean mass development—it amplifies the effects of proper training and nutrition but doesn't create dramatic overnight changes. Expect modest but visible improvements in lean mass over 4-8 weeks if you're training hard and eating right. It's a support tool, not a replacement for the hard work.
GHRP-2 is not FDA approved for any use in the U.S. It is approved in Japan as a diagnostic agent for GH deficiency testing. 56 In the U.S., GHRP-2 exists in a gray zone—it's not explicitly illegal to possess for personal research use, but it's not approved for human consumption, and clinical use would require physician oversight and institutional approval. Always verify local regulations before use and consult with a healthcare provider.
Most therapeutic research protocols run 4-8 weeks. Results typically plateau after 6 weeks as your body adapts to the stimulus. Standard practice is: 4-6 weeks on, then 2-4 weeks off to allow recovery and prevent desensitization. 7 Longer cycles (12+ weeks) don't produce proportionally greater results and increase risk of side effects. Think of it as periodized training—on-off cycling maintains responsiveness and safety.
There's no physical dependence or dangerous withdrawal from stopping GHRP-2. Your GH levels simply return to baseline. However, the improvements you've made (muscle, recovery, etc.) will gradually regress if you stop training and eating well. It's not dangerous to stop—you just won't get the ongoing benefits. Plan your off-cycle strategically to maintain progress through proper training and nutrition.
Yes. GHRP-2 is not gender-specific and works similarly in men and women. 7 Dosing is typically the same (100-300 mcg). Women may experience similar side effects and benefits. The main consideration is pregnancy—GHRP-2 should not be used during pregnancy or while breastfeeding due to lack of safety data. 5 Otherwise, women interested in recovery and lean mass development can use GHRP-2 as effectively as men.
This is a legitimate concern, since GH makes cells multiply. 15 However, there's no clinical evidence that GHRP-2 directly causes cancer in short-term human use. Most concerns are theoretical, based on the fact that GH promotes growth. People with a cancer history or genetic risk should avoid GHRP-2 without medical clearance. For healthy people using 4-8 week cycles, cancer risk is not established, but long-term safety data is simply lacking, so caution is warranted.
This is challenging since GHRP-2 isn't commercially available through legitimate pharmaceutical channels in most countries. 5 Red flags for counterfeit: extreme cheapness, no third-party testing certificates available, seller unable to provide batch documentation, or solution that appears cloudy or discolored. If possible, request or obtain third-party testing (HPLC or mass spectrometry) to verify peptide identity and purity. If in doubt, don't use it.
16 sources
Every numbered marker on this page points to one of these. Same sources, same numbering as the Pralmorelin (GHRP-2) research profile on Peptide Initiative.
Want the deep science?
Every claim on this page traces back to the research database behind Peptide Initiative — studies, citations, clinical trial data, and the technical detail we deliberately left out here.
Open the research profileThis guide is education, not medical advice. Pralmorelin (GHRP-2) is a research compound that is not FDA-approved for human use. Talk to a clinician before taking anything.
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