GHRP-2 vs IGF-1 LR3
A neutral, side-by-side comparison of two performance & growth hormone peptides — their mechanisms, dosing ranges, administration routes, side effects, and research evidence. For research and educational purposes only.
GHRP-2
GHRP-2 is a synthetic hexapeptide that acts as a ghrelin mimetic, stimulating the pituitary gland to secrete growth hormone (GH). It is one of the most potent GH secretagogues studied, producing stronger GH pulses than GHRP-6 with comparatively less appetite stimulation.
Full profileIGF-1 LR3
IGF-1 LR3 (Long Arg3 IGF-1) is a synthetic analogue of Insulin-like Growth Factor 1 with an amino acid substitution at position 3 and a 13-amino acid N-terminal extension. These modifications prevent binding to IGF-binding proteins (IGFBPs), dramatically extending its half-life from ~12 minutes (native IGF-1) to approximately 20–30 hours. IGF-1 LR3 is widely used in research for its ability to promote cellular growth, protein synthesis, hyperplasia, and nutrient uptake into muscle tissue.
Full profile| GHRP-2 | IGF-1 LR3 | |
|---|---|---|
| Category | Performance & Growth Hormone | Performance & Growth Hormone |
| Also known as | Growth Hormone Releasing Peptide-2, Pralmorelin, KP 102 | Insulin-like Growth Factor-1 Long R3, Long R3 IGF-1, Increlex (human equivalent) |
| Evidence | Preclinical only | Research-stage |
| Dosing range | 100mcg–300mcg mcg, 1–3 times daily, on an empty stomach | 20mcg–100mcg mcg, Once daily post-workout, on training days only (common protocol) |
| Administration | Subcutaneous injection, Intramuscular injection | Subcutaneous injection, Intramuscular injection (into the trained muscle — site-specific protocols) |
| Key side effects | Increased hunger (less than GHRP-6), Elevated cortisol and prolactin at high doses, Water retention, Injection site irritation | Hypoglycemia (clinically significant — monitor blood sugar carefully), Jaw and organ growth with chronic high-dose use (theoretical at research doses), Fatigue and headaches, Joint pain |
| Cited sources | 3 references | 3 references |
Key differences
- Evidence level differs: GHRP-2 is preclinical only, while IGF-1 LR3 is research-stage.
- Administration: GHRP-2 — Subcutaneous injection, Intramuscular injection; IGF-1 LR3 — Subcutaneous injection, Intramuscular injection (into the trained muscle — site-specific protocols).
- Frequency: GHRP-2 is typically 1–3 times daily, on an empty stomach; IGF-1 LR3 is Once daily post-workout, on training days only (common protocol).
How each works
GHRP-2
GHRP-2 has been extensively studied in both animal and human subjects. Clinical trials have demonstrated significant GH elevation in healthy adults, with a peak GH pulse occurring 15–30 minutes post-injection. Studies show it increases IGF-1 levels with chronic use and may have mild cardioprotective properties. Unlike GHRP-6, it has a lower propensity to stimulate cortisol and prolactin at standard doses.
IGF-1 LR3
In vitro and animal research establishes IGF-1 LR3 as a potent anabolic and growth-promoting agent. It activates the IGF-1 receptor (IGF-1R) and downstream PI3K/Akt and MAPK/Erk pathways, promoting skeletal muscle hypertrophy and satellite cell activation. Its extended half-life makes it far more active systemically than native IGF-1. Research also documents its role in connective tissue repair, nerve regeneration, and fat oxidation. Human research is limited — most data comes from cancer cell biology and athletic performance settings.
This comparison aggregates public research and structured profile data for informational purposes only. It is not medical advice and does not recommend either compound for human use. Consult a qualified healthcare provider before considering any peptide.