Sermorelin: The Classic GHRH Fragment and Its Fast Clearance
A classic 29-amino-acid GHRH fragment, historically FDA-approved as Geref — clears fast, keeping GH release in its natural pulsatile rhythm.
What is Sermorelin?
Sermorelin is a 29-amino-acid fragment of growth hormone-releasing hormone (GHRH 1-29), retaining full biological activity of the native 44-amino-acid hormone. It was FDA-approved as Geref for diagnostic and GH-deficiency use before being discontinued from the market for commercial reasons, though it remains a classic, well-characterized GH secretagogue in research and clinic use. Because it clears the body quickly, it's thought to preserve the pituitary's natural pulsatile GH release pattern better than longer-acting GHRH analogs. Supporting body-composition and sleep data comes mostly from studies of a closely related compound (GHRH 1-29) given intravenously, rather than sermorelin itself administered by injection — an important distinction when weighing the evidence.
Quick facts
- Sequence
- GHRH(1-29) — 29-amino-acid fragment of native growth hormone-releasing hormone
- Half-Life
- ~10-20 minutes
- Class
- GHRH analog / fragment
- Brand Names
- Geref (historically FDA-approved, since discontinued from commercial distribution)
- Legal Status
- Not currently sold as an FDA-approved commercial drug (Geref discontinued); available via compounding pharmacies by prescription, and sold RUO by research vendors
- Category
- Growth Hormone
- Storage
- Store the lyophilized vial refrigerated (2-8°C) or at -20°C, away from light. Once reconstituted, keep refrigerated at 2-8°C and use promptly.
Dosing at a glance
5mg vial + 2mL bacteriostatic water = 2500mcg/mL. Run the numbers in the reconstitution calculator.
Doses shown are those reported in published research, not a recommendation.
What the evidence supports
| Claim | Grade | Basis |
|---|---|---|
| Body Composition | Cgrade | Khorram 1997 (JCEM, n=19): 16 weeks of a close-cousin GHRH(1-29) compound grew lean mass ~1.26kg in men; women saw no change. |
| Muscle Growth | Cgrade | Same Khorram 1997 data — modest lean-mass gain, mostly in older/GH-deficient adults. |
| Sleep Quality | Cgrade | Antonijevic/Frieboes 2000 (n=75): IV GHRH(1-29) deepened sleep in men but worsened it in women — a different compound/route than injected sermorelin. |
Sermorelin Mechanism of Action
The Minimal Active Fragment of GHRH
Sermorelin reproduces the first 29 amino acids of native growth hormone-releasing hormone (GHRH) — the minimal fragment shown to retain full biological activity of the complete 44-amino-acid hormone. It binds the pituitary's GHRH receptor, triggering endogenous GH release.
Fast Clearance Preserves Natural Pulsatility
Sermorelin clears the body quickly — its short half-life means it produces a single, physiological GH pulse rather than sustained receptor stimulation. This is thought to better preserve the pituitary's natural pulsatile release pattern compared to longer-acting, DAC-modified GHRH analogs like CJC-1295.
Sermorelin Dosage and Protocols
Pre-Bed Dosing
Research-typical dosing is 200–300mcg subcutaneous once daily, timed before bed to align with the body's natural nighttime GH pulse — mirroring how sermorelin was dosed during its FDA-approved Geref era.
Sermorelin Side Effects and Safety
Well-Characterized, Generally Mild
Given its history as an approved drug, sermorelin has a comparatively well-characterized safety profile among GH secretagogues — injection-site flushing, headache, and dizziness are the most commonly reported effects. Active malignancy is a precautionary contraindication given the downstream IGF-1 stimulation shared across the GH-secretagogue class.
Sermorelin Research Evidence
A Real Approval, Discontinued for Business Reasons
Sermorelin was FDA-approved under the brand Geref for diagnostic testing and GH-deficiency treatment before being discontinued from commercial distribution — a business decision, not a safety withdrawal. It remains a well-characterized, classic GH secretagogue.
An Important Evidence Caveat
Much of sermorelin's supporting body-composition and sleep data — including the Khorram 1997 study showing ~1.26kg lean-mass gain in 19 older adults over 16 weeks — actually tested GHRH(1-29), a closely related compound, sometimes by a different route (IV) than the subcutaneous injection people research today. The read-across to injected sermorelin specifically is reasonable given the shared active sequence, but it's indirect, not a direct trial of the product itself.
Sermorelin Stacking and Combinations
Sermorelin + Ipamorelin
Sermorelin is commonly paired with Ipamorelin — a GHRH analog plus a ghrelin-receptor agonist hitting the GH axis from two distinct receptor angles, the same combined-mechanism logic behind REGEN's existing CJC-1295/Tesamorelin + Ipamorelin blends.
Sermorelin Pharmacokinetics
Very Short Half-Life
Sermorelin's half-life of roughly 10-20 minutes is what produces its brief, physiological-style GH pulse rather than sustained receptor stimulation — the same short-acting design philosophy behind CJC-1295 (no-DAC).
Contraindications
- active malignancy
- pregnancy
Trials and reviews
- Khorram GHRH(1-29) body compositionJCEM1997
~1.26kg lean-mass gain in older men over 16 weeks (n=19)
- Antonijevic/Frieboes sleep studysleep-lab trial2000
IV GHRH(1-29) deepened sleep in men, worsened it in women (n=75)
Frequently asked questions
What is a typical Sermorelin dose?
Published research protocols report 200–300 mcg, pre-bed. This is the range described in the literature, not a recommendation.
What is the half-life of Sermorelin?
~10-20 minutes.
Is Sermorelin backed by strong evidence?
Sermorelin carries a REGEN research grade of C. REGEN Research Tier C — modest supporting data, much of it from a related compound rather than sermorelin itself.
How is Sermorelin administered?
Routes reported in the literature: subcutaneous.
Who should avoid Sermorelin?
Contraindications noted in the literature include active malignancy, pregnancy.
References
- Khorram GHRH(1-29) body composition study · Khorram O, et al. · 1997