Hexarelin
Synthetic growth hormone secretagogue (hexapeptide)
- Class
- GH secretagogue
- Half-life
- ~70 min
- Route
- Subcutaneous (SubQ)
- Cadence
- Daily
- Evidence
- Mixed / early human
Overview
Hexarelin is a synthetic growth-hormone-releasing peptide that briefly looked like it might be a cleaner alternative to GHRP-6. Single subcutaneous injection triggers a sharp GH pulse — about 3-4× baseline in young adults, lasting 2-3 hours. The catch: it stops working after a few weeks. Tachyphylaxis (the medical term for tolerance) sets in faster and harder than with any other GH secretagogue — you're back to near-baseline GH output by week 2-4 even if you keep dosing daily.
It hit phase-2 trials for growth-hormone deficiency in the late 90s but was never approved anywhere. The desensitisation issue killed its commercial prospects, and most research stopped around 2005. What kept it in the literature was an unexpected finding: it also binds CD36, a scavenger receptor involved in heart protection. Some animal studies showed cardioprotective effects independent of GH — smaller infarct size after induced heart attacks in rats, better ejection fraction in failing hearts. Whether that translates to humans is unknown; no cardiac trials were ever completed.
The peptide you'd get from research vendors now is usually unregulated, variable purity, and comes with zero guarantee of actual hexarelin content. Given the fast tolerance and the lack of human outcome data, it's mostly a historical curiosity at this point — ipamorelin and CJC-1295 are cleaner, better-studied options for GH release without the desensitisation problem.
Safety considerations
A few of the safety signals worth knowing — the full list, with dosing context and what to monitor, is inside AIx Core.
- Not approved for human use by FDA, EMA, MHRA, or any other regulator. Research-market peptide purity is unverified.
- Tachyphylaxis (tolerance) within 2-4 weeks makes extended use futile — most of the GH effect is gone by week 3 even if you keep dosing.
- Prolactin elevation is common and can cause gynecomastia, libido suppression, or galactorrhea with repeated dosing.
+ 3 more safety notes inside AIx Core →
Commonly monitored
Markers and signals people track when researching Hexarelin.
- IGF-1 (but expect it to plateau or fall after a few weeks as GH response fades)
- Prolactin — watch for elevated levels with chronic use
- Cortisol — hexarelin raises it acutely; unclear if chronic use causes problems
- Fasting glucose — GH secretagogues can impair insulin sensitivity
- Subjective: sleep quality, joint comfort, recovery (the usual GH-proxy markers)
Frequently asked questions
What is Hexarelin?
Synthetic growth hormone secretagogue (hexapeptide). Hexarelin is a synthetic growth-hormone-releasing peptide that briefly looked like it might be a cleaner alternative to GHRP-6. Single subcutaneous injection triggers a sharp GH pulse — about 3-4× baseline in young adults, lasting 2-3 hours. The catch: it stops working after a few weeks. Tachyphylaxis (the medical term for tolerance) sets in faster and harder than with any other GH secretagogue — you're back to near-baseline GH output by week 2-4 even if you keep dosing daily.
How is Hexarelin administered?
Subcutaneous (SubQ), typically daily.
What is the half-life of Hexarelin?
~70 min — Short plasma half-life but triggers multi-hour GH pulse.
Is Hexarelin approved for human use?
Hexarelin is investigational — not approved by the FDA, EMA, or MHRA for human use at the time of writing.
What does the evidence show for Hexarelin?
Evidence tier: Mixed / early human. Bowers 1997 (J Endocrinol): single 2 μg/kg dose in young men gave peak GH of ~30 μg/L vs ~8 μg/L baseline — about 3.5× increase. Effect peaked at 30-60 min post-injection.
What is commonly monitored when researching Hexarelin?
Commonly tracked markers + signals: IGF-1 (but expect it to plateau or fall after a few weeks as GH response fades), Prolactin — watch for elevated levels with chronic use, Cortisol — hexarelin raises it acutely; unclear if chronic use causes problems, Fasting glucose — GH secretagogues can impair insulin sensitivity, Subjective: sleep quality, joint comfort, recovery (the usual GH-proxy markers).
Related compounds
Open this in AIx Core for the full picture
Mechanism breakdown, receptor pathway diagram, full safety list, monitored items, source citations, and one-tap add-to-protocol. Free with any account.