GHRP-2

Step	Weeks	Dose	Purpose
Week 1	—	100 mcg	Assess cortisol/hunger response
Weeks 2–12	—	200–300 mcg	Maximum GH protocol

Beginner Protocol

Intermediate Protocol

Advanced Protocol

Reconstitution and handling notes

Stacking Notes

Additional Dosage Notes

Foundational Bowers Research

The entire GHRP class emerged from the laboratory of Cyril Y. Bowers at Tulane University. [Bowers et al., 1991] demonstrated that GHRP-6 and early analogs synergize dramatically with GHRH to produce GH release far exceeding either compound alone. This synergy principle became the foundational pharmacology of every subsequent GHS compound including GHRP-2, ipamorelin, hexarelin, MK-677, and endogenous ghrelin itself.

[Ghigo et al., 1994] established GHRP-2's dose-response in adult humans, documenting robust GH release at doses as low as 0.3 mcg/kg IV and plateau effects at 1-2 mcg/kg. Oral, intranasal, and subcutaneous routes were subsequently characterized, with SC administration emerging as the preferred route for research and off-label use.

Adult GHD Diagnostic Approval - Japan

Japan approved pralmorelin (GHRP-2, marketed as GHRP Kaken 100) as a diagnostic agent for adult growth hormone deficiency around 2006, offering an alternative to the insulin-tolerance test (ITT). [Chihara et al., 2007] ([PMID:17609397]) validated the registered test protocol:

• Single fixed 100 mcg IV bolus of GHRP-2 produces a reliable, reproducible GH response - a serum GH peak occurred within 60 minutes in every subject
• Discriminatory power was strong: peak GH was markedly lower in GHD patients than in healthy subjects, with a 15 mcg/L cut-off corresponding to the 3 mcg/L threshold of the ITT
• Safety profile was significantly better than ITT - no hypoglycemia risk, no seizure risk, minimal GI upset
• Convenience - a single IV bolus replaced the multi-hour ITT procedure

The approval established GHRP-2 as a legitimate, regulated medical product in at least one major healthcare system, and the diagnostic data also validated the fundamental GH-release pharmacology in humans.

Pediatric Growth Studies - Mericq, Pihoker

[Pihoker et al., 1997] ([PMID:9390009]) treated 15 children with short stature - roughly half with GH deficiency and half with idiopathic short stature - using intranasal GHRP-2, with a main follow-up of about 6 months (a subset continued to 18-24 months). Height velocity rose from roughly 3.7 to 6.1 cm/year at 6 months. [Mericq et al., 1998] ([PMID:9661608]) gave graded subcutaneous GHRP-2 to six prepubertal GH-deficient children across about 8 months and saw a dose-related rise in overnight GH secretion and growth velocity, though the per-injection effect was brief and IGF-1 did not consistently increase. A follow-up 12-month oral GHRP-2 study in GH-deficient children ([Mericq et al., 2003] - [PMID:14513874]) found only a transient appetite increase and no significant chronic change in BMI. Taken together, these small pediatric studies showed real but modest growth-velocity gains over roughly 8-12 months and helped motivate the search for longer-acting secretagogues.

The broader GHRP-2 literature also documented cortisol and prolactin cross-effects, which later motivated the development of more selective GHS compounds like ipamorelin. Those cross-pathway elevations were considered clinically acceptable but not ideal for chronic therapy.

Adult Body Composition Research

Limited formal adult body composition trial data exists for GHRP-2 alone, because the research pathway pivoted toward more selective compounds (ipamorelin) and longer-acting analogs (MK-677) in the 2000s. Adult-focused data comes largely from:

• Single-dose pharmacokinetic and GH-response studies ([Ghigo 1994])
• Short-duration combination trials of GHRP-2 + GHRH ([Bowers 1991])
• Observational data from peptide therapy clinics (not peer-reviewed)

The absence of a clean adult body-composition trial with GHRP-2 monotherapy is a real gap in the evidence base. Practitioners who use GHRP-2 rely on the mechanistic overlap with ghrelin/GHS-R1a pharmacology and the substantial body of supportive data from related compounds.

Safety Across the Literature

Across pediatric, adult, and diagnostic-testing datasets, GHRP-2 has an acceptable safety profile for short-term and intermittent use. Recurring observations include:

• Mild transient cortisol elevation (+15-25% above baseline)
• Modest prolactin elevation (usually clinically trivial)
• Appetite stimulation (dose-dependent)
• Injection site reactions (mild, self-limiting)
• Rare flushing or transient hypotension following rapid IV bolus

No consistent serious adverse event signal has emerged. The cortisol and prolactin effects are the main mechanistic differentiators from cleaner GHS compounds and the primary rationale for choosing ipamorelin over GHRP-2 for long-term daily protocols.

Common (dose-dependent)

• Increased appetite / hunger — GHRP-2 is a ghrelin-receptor agonist, and ghrelin is the body's primary hunger signal. Expect measurable appetite stimulation starting ~30 minutes post-injection and peaking at 1-2 hours. Beneficial in caloric surplus phases; problematic in deficit phases.
• Transient cortisol elevation — +15-25% above baseline in the 60-90 min post-injection window. Usually clinically trivial in healthy users but relevant in users with HPA axis dysregulation, adrenal insufficiency, or stress-driven cortisol issues.
• Modest prolactin elevation — usually not clinically meaningful but relevant in users with baseline prolactin concerns or prolactin-sensitive pathologies.
• Injection site reactions — mild erythema or transient itching at SC site; site rotation minimizes.
• Flushing — warm, pink flush in face/neck post-injection, fading within 15-30 minutes.

Less Common

• Mild fluid retention — particularly in first 2-3 weeks of daily use; usually self-limiting.
• Vivid dreams — secondary to improved slow-wave sleep when dosed at bedtime.
• Transient insulin sensitivity reduction — GH-axis stimulation modestly reduces insulin sensitivity; monitor HbA1c and fasting glucose in extended use.
• Headache — mild, typically responsive to hydration.
• Nausea — uncommon at SC doses; more common with high IV boluses.

Rare

• Significant hypotension — primarily with IV administration; SC route rarely produces meaningful BP effects.
• Hypersensitivity reactions — rare local or systemic allergic response.
• Paresthesia or scalp tingling — transient, benign.
• Dysgeusia — metallic or unusual taste immediately post-injection.

Cumulative with Long-term Use

• Insulin resistance — sustained daily dosing over months can modestly reduce insulin sensitivity. Monitor HbA1c and fasting insulin quarterly.
• Receptor desensitization — unlike GHRH analogs which retain pituitary responsiveness well, chronic high-dose GHS can produce measurable GHS-R1a tachyphylaxis. Cycling protocols (5 on / 2 off, or 8 weeks on / 2 weeks off) help maintain responsiveness.
• HPA axis adaptation — persistent low-grade cortisol elevation over months could theoretically contribute to HPA dysregulation in susceptible users. Periodic ACTH/cortisol monitoring in chronic protocols is sensible.

Theoretical Long-term Concerns

As with all GH-axis interventions, the IGF-1 elevation produced by GHRP-2 raises a theoretical concern around chronic supraphysiologic mitogenic signaling and cancer risk. No causal link has been demonstrated in trials, but mechanistic plausibility supports conservative dosing, periodic IGF-1 monitoring, and avoidance in users with active malignancy or strong family history of hormonally-responsive cancers.

Signs You Are Overdosing

• Persistent joint discomfort or peripheral edema
• Carpal tunnel-like symptoms
• Persistent elevated fasting glucose
• Unexpected weight gain beyond what caloric intake accounts for
• Sleep apnea worsening

Any of these warrant dose reduction or discontinuation.