GHRH vs GHRP: Two Sides of the GH Coin
Sermorelin is a GHRH (growth hormone releasing hormone) analog — it amplifies the size of GH pulses by stimulating the GHRH receptor on the pituitary. Ipamorelin is a GHRP (growth hormone releasing peptide) — it initiates GH pulse release by activating the ghrelin receptor (GHS-R1a).
Together they are synergistic (CJC-1295 + Ipamorelin is the gold standard stack). But as standalone options, they serve different therapeutic goals.
Sermorelin: The FDA-Approved GHRH Analog
Sermorelin (Geref) was FDA-approved in 1997 for diagnosing and treating GH deficiency in children, though it was later discontinued commercially. It remains available through compounding pharmacies.
Mechanism: Sermorelin binds the GHRH receptor, telling the pituitary to release a larger-than-normal GH pulse. It preserves the body's natural feedback mechanisms — the pituitary still controls pulse timing.
Half-life: 10-20 minutes. Standard dose: 200-300mcg SubQ before bedtime. Because of its short half-life, timing is critical.
Ipamorelin: The Clean GHRP
Ipamorelin is a selective ghrelin mimetic that triggers GH pulse initiation. Its key advantage over other GHRPs (GHRP-2, GHRP-6, hexarelin): it does NOT elevate cortisol, prolactin, or significantly stimulate appetite.
This selectivity makes it the safest GHRP for long-term use. GHRP-6 causes intense hunger (useful for underweight patients, problematic for others). Hexarelin is more potent but elevates cortisol. GHRP-2 is intermediate.
Half-life: approximately 2 hours. Standard dose: 200-300mcg SubQ, 2-3 times daily on an empty stomach.
Which Should You Choose?
Choose Sermorelin if: You want a single-agent approach with FDA historical approval, you prefer once-daily dosing (before bed), and your pituitary has adequate ghrelin receptor function.
Choose Ipamorelin if: You want the cleanest hormonal profile (no cortisol/prolactin elevation), can commit to 2-3 daily injections, and prefer a more potent GH pulse initiation.
Best option: Stack them together (or use CJC-1295 no DAC + Ipamorelin for convenience — CJC-1295 is a modified GHRH analog like sermorelin but with slightly longer half-life). The combination produces 2-5x greater GH output than either alone.
Medical Disclaimer: This article is for educational purposes only. Consult a qualified healthcare provider before using any GH secretagogue.