GHRP-2: the basics
What is it?
A lab-made chain of six amino acids that makes the pituitary gland release growth hormone. It acts on the same receptor as ghrelin, the body's hunger hormone.
Research paper 1 ↗Research paper 2 ↗Research paper 3 ↗What do people claim it helps with?
Sellers promote it for muscle growth, fat loss, recovery and appetite. Those uses have not been shown in reliable treatment trials.
What has research actually shown?
Doctors in Japan use it as a one-off test: a healthy pituitary releases a lot of growth hormone after a dose, while a damaged one does not. Small treatment studies raised hormone levels but did not show clear health benefits.
Research paper 1 ↗Research paper 2 ↗Research paper 3 ↗Has this been demonstrated in people?
Human diagnostic studies, including a 135-person validation study, plus a few very small treatment studies. There are no large trials of long-term treatment.
Research paper 1 ↗Research paper 2 ↗Research paper 3 ↗What side effects, risks and unknowns should I understand?
FDA reports serious adverse events in people who received GHRP-2, including higher insulin needs, infection, pancreatitis and deaths of critically ill study subjects, though causes were not established.
FDA safety information 1 ↗FDA briefing 2 ↗Is it an approved medicine?
No FDA-approved medicine contains this peptide. In Japan it is approved only as a diagnostic test agent. FDA lists injectable and nasal compounded GHRP-2 as a substance that may present significant safety risks.
FDA safety information 1 ↗FDA briefing 2 ↗Approval here means U.S. FDA approval and applies to a particular product, formulation and use. This is a starting overview, not a complete side-effect list. Sources checked 10 October 2026; independent scientific review pending.
How is it used or studied?
In Japan it is given as a single injection by doctors during a hormone test. Products sold online are not the approved Japanese diagnostic product.
Different routes and formulations can have different effects. A study of one product does not validate every product with the same peptide name.
A common misunderstanding
Approval as a one-time diagnostic test in Japan is not approval to use it repeatedly as a body-building or anti-aging treatment.
What should I ask a clinician?
- What diagnosis or goal are we trying to address, and what established options are available?
- Was the expected benefit shown in people like me, using this exact product?
- How could my medicines, health conditions or pregnancy plans affect the risks?
- What monitoring is needed, and what would tell us the treatment is helping or should be stopped?
What do the research words mean?
- Peptide
- A short chain of amino acids, the building blocks of proteins.
- Preclinical
- Research in cells, tissues or animals before dependable treatment evidence in people.
- Controlled trial
- A study comparing a treatment with another treatment or a placebo to help separate its effects from other explanations.
- Biomarker
- A measurement, such as a hormone level. A change does not necessarily mean someone feels better or lives longer.
GHRP-2 Evidence & Clinical Profile
Human Study Limits
GHRP-2 has been investigated in clinical contexts. Patient outcomes must be evaluated against study size, design, and control cohorts.
Laboratory & In Vivo Assays
Cellular and animal disease models examine receptor binding affinities and signaling cascades, which require human confirmation.
What is GHRP-2?
Pralmorelin (Growth Hormone-Releasing Peptide-2) is GHRP-2, also called pralmorelin, is a synthetic six-amino-acid peptide that triggers growth hormone release through the ghrelin receptor (GHS-R1a). In Japan it is used as a diagnostic agent to test for GH deficiency. It is not FDA-approved, and FDA lists injectable and nasal compounded GHRP-2 as a possible significant safety risk. Aliases include: Pralmorelin, KP-102, GHRP Kaken, D-Ala-D-2Nal-Ala-Trp-D-Phe-Lys-NH2.
- Sequence (one-letter)
- (D-A)-(D-2Nal)-A-W-(D-F)-K-NH2
- Molecular formula
- C45H55N9O6
- Molecular weight
- 818.0 g/mol
- CAS Number
- 158861-67-7
- UNII Code
- E6S6E1F19M
- PubChem CID
- 6918245
Identifiers checked against PubChem and FDA's Global Substance Registration System on 13 October 2026. FDA substance record ↗ · PubChem record ↗ See all names and codes in the peptide name index.
Clinical Trials & Human Cohorts
Human research can examine tolerability, symptoms or patient outcomes. The design and comparator determine what each result can establish.
A simple diagnostic test using GH-releasing peptide-2 in adult GH deficiency [1]
What was reported
Peak GH after GHRP-2 was far lower in GH-deficient patients than in healthy people, and repeat tests gave similar results.
What limits the conclusion
A diagnostic study by the KP-102 Study Group in Japan; it says nothing about treatment benefits.
Clinical usefulness of the GHRP-2 test for hypothalamic-pituitary disorder [4]
What was reported
The ACTH response during the GHRP-2 test helped flag pituitary-related adrenal insufficiency that often occurred alongside GH deficiency.
What limits the conclusion
Small single-center study with a cut-off chosen from the same data; it needs confirmation elsewhere.
Effects of eight months treatment with graded doses of a GH-releasing peptide in GH-deficient children [2]
What was reported
GHRP-2 raised overnight GH release and was well tolerated, but IGF-I and IGFBP-3 did not rise.
What limits the conclusion
Six children and no control group. The authors concluded a longer-acting form would be needed for therapy.
Combined GHRP-2, TRH and GnRH in men with prolonged critical illness [3]
What was reported
Over 5 days, a GHRP-2 infusion restored GH secretion and IGF-I, but GHRP-2 alone did not reduce protein breakdown; the combination with TRH and GnRH did.
What limits the conclusion
Small, short study of hormone and metabolic markers, not survival or recovery.
How the compound may work
Mechanisms describe how GHRP-2 may affect biological processes. Laboratory findings and patient outcomes answer different questions.
GHS-R1a agonism
GHRP-2 belongs to the GH-releasing peptide family that acts on the GH secretagogue receptor (GHS-R1a), later identified as the ghrelin receptor. [5]
ACTH and cortisol release
Besides GH, GHRP-2 raises ACTH and cortisol in people. Japanese clinicians use this to screen adrenal function during the same test. [4]
Areas Being Studied
These research topics reflect active areas of scientific exploration, distinct from unverified commercial marketing claims.
GH deficiency testing
Provocative test for adult GH deficiency as an alternative to the insulin tolerance test. [1]
Pituitary-adrenal assessment
Using the ACTH and cortisol response to screen for secondary adrenal insufficiency. [4]
Critical illness
Reactivating suppressed hormone axes in prolonged critical illness; FDA notes serious adverse events in such patients. [3]
Compare the study designs.
| Study | Design / sample | Outcome type | Key limitation |
|---|---|---|---|
| Adult GHD diagnosis · 2007 [1] | Multicenter diagnostic validation study n = 135 |
Clinical endpoint evaluation | A diagnostic study by the KP-102 Study Group in Japan; it says nothing about treatment benefits. |
| Pituitary disorders · 2022 [4] | Single-center clinical study n = 36 |
Clinical endpoint evaluation | Small single-center study with a cut-off chosen from the same data; it needs confirmation elsewhere. |
| GHD children, 8 months · 1998 [2] | Uncontrolled dose-escalation study n = 6 |
Clinical endpoint evaluation | Six children and no control group. The authors concluded a longer-acting form would be needed for therapy. |
| Prolonged critical illness · 2002 [3] | Randomized placebo-controlled study n = 33 |
Clinical endpoint evaluation | Small, short study of hormone and metabolic markers, not survival or recovery. |
Regulatory Status & Clinical Safety
Regulatory Classification
Not FDA-approved. Pralmorelin is marketed in Japan as a diagnostic agent (KEGG lists approval in 2004). FDA: 503B category 2 for injectable and nasal routes since September 29, 2023; 503A category 3. WADA S2 prohibited substance.
Safety Realities & Impurities
Safety depends on the molecule, formulation, route and evidence. A laboratory purity measurement alone cannot establish safety for human use.
Clinical Trials Registry Records
Official registry records from ClinicalTrials.gov. Study registration does not imply government endorsement or guaranteed efficacy.
WADA & Anti-Doping Regulations
WADA Section S2: Prohibited Substance
The World Anti-Doping Agency (WADA) classifies GHRP-2 under Section S2 of the Prohibited List. Prohibited at all times (in- and out-of-competition). Last verified: October 2026.
Research Timeline
-
1996
Receptor identified
The GH secretagogue receptor that GHRP-2 activates is cloned. [5]
-
2004
Japanese approval
Pralmorelin (GHRP Kaken) is approved in Japan as a diagnostic agent for pituitary GH secretion. [8]
-
2007
Diagnostic validation
The KP-102 Study Group publishes its 135-person validation of the GHRP-2 test. [1]
-
2023
FDA safety category
FDA places injectable and nasal GHRP-2 in 503B category 2, citing immunogenicity, impurities and reported serious adverse events. [6]
-
2025
Other routes under review
FDA's 503B list keeps GHRP-2 for non-injectable, non-nasal routes in category 1 (under evaluation). [7]
-
2026
Banned in sport
WADA's 2026 Prohibited List names GHRP-2 (pralmorelin) in class S2. [9]
What Researchers Still Don't Know
Long-term safety profiles
Multi-year observational data in broader heterogeneous cohorts remains uncharacterized.
Optimal dose-response thresholds
Comparative trials optimizing minimal effective exposure versus adverse event rates.
Formulation bioavailability
Differences between oral, subcutaneous, and modified peptide delivery vehicles.
References
Primary sources verified against PubMed / NLM and regulatory databases.
-
Diagnostic validation study
A simple diagnostic test using GH-releasing peptide-2 in adult GH deficiency. ↗ (external website)
- Uncontrolled dose-escalation study
- Randomized study in critical illness
- Clinical diagnostic study
- Receptor cloning study
- FDA safety list
- FDA compounding list
-
Drug database (Japan)
KEGG DRUG D02040: Pralmorelin dihydrochloride (GHRP), Japanese diagnostic agent ↗ (external website)
-
Anti-doping rule
World Anti-Doping Code International Standard: Prohibited List 2026 ↗ (external website)