Educational reference only. Informational material drawn from peer-reviewed literature. Not medical advice and not a recommendation to use, dose, or modify any therapy. Decisions about hormone therapy should be made with a qualified healthcare provider.
Overview
Overview
Sermorelin, also called GRF 1-29 (growth hormone releasing factor, amino acids 1–29), is a synthetic 29-amino acid peptide that represents the biologically active N-terminal fragment of growth hormone-releasing hormone (GHRH). It is a growth hormone secretagogue: it does not contain or supply growth hormone itself but stimulates the pituitary gland to produce and release endogenous GH. This is a fundamentally different mechanism than direct GH (somatropin) administration and is the basis for sermorelin's claim of more "physiological" GH elevation.
Sermorelin has an unusual regulatory history: it received FDA approval in 1990 (under the brand name Geref / Geref Diagnostic, EMD Serono) for growth hormone deficiency diagnosis and treatment, then the original commercial product was discontinued in 2008 for business reasons (not safety concerns). The compound remains technically FDA-approvable and is widely available through compounding pharmacies and unregulated sources.
The relationship between sermorelin and longer-acting variants:
- Sermorelin = native GRF 1-29 = ~12 min half-life
- Mod GRF 1-29 = CJC-1295 No DAC = ~30 min half-life (tetrasubstituted variant)
- CJC-1295 with DAC = albumin-bound version = ~6–8 day half-life
Forms
Available forms & half-lives
| Form | Approximate half-life |
|---|---|
| Subcutaneous sermorelin (native GRF 1-29) | ~12 minutes |
| Modified GRF (1-29) = CJC-1295 No DAC (longer-acting variant) | ~30 minutes |
What it does
Main effects
- Diagnostic GH stimulation testing: the original FDA-approved indication; intact pituitary responds normally to sermorelin, distinguishing pituitary-level GH deficiency from hypothalamic causes
- Pediatric growth hormone deficiency therapy: increased linear growth velocity and IGF-1 levels in children with intact hypothalamic-pituitary axis
- Endogenous GH release via GHRH receptor agonism: stimulates pituitary somatotrophs to synthesize and release GH; serum GH typically 2–10× baseline within 30–60 minutes
- IGF-1 elevation: typically 20–30% above baseline with chronic use
- Preserved pulsatile GH release pattern: more "physiological" than direct GH (somatropin) administration; preserves negative feedback regulation; limited by pituitary capacity (cannot overshoot)
- No pituitary suppression: unlike exogenous GH, sermorelin preserves endogenous GH production
- Acts at a different receptor from the GHRPs: sermorelin binds the GHRH receptor, while growth hormone releasing peptides bind GHS-R1a (the ghrelin receptor); the two pathways are pharmacologically distinct
- Anti-aging / body composition (non-medical use): claimed restoration of declining GH secretion, improved body composition (increased lean mass, decreased fat), improved sleep quality, possibly improved bone density and skin quality; based on extrapolation from approved indications, weaker direct evidence
What to watch for
Common side effects
- Injection site reactions (pain, redness, swelling): most common adverse effect, ~16–17% of patients in clinical trials; mild and self-limited
- Mild constitutional symptoms (flushing, headache, dizziness, rare nausea): typically diminish with continued use
- Mild insulin resistance and modest fasting glucose elevation: GH has anti-insulin effects; caution in diabetic patients
- IGF-1 elevation: monitoring recommended to avoid supraphysiological elevation
- Theoretical cancer concerns: IGF-1's role in cell proliferation; sermorelin-specific cancer data limited; conservative recommendation to avoid in active malignancy
- Acromegaly-like effects largely avoided: secretagogue mechanism preserves feedback regulation, unlike direct GH; this is a theoretical safety advantage
- Mild fluid retention: GH-related
- Sleep disturbance: variable; can be positive (improved deep sleep) or negative
- Occasional joint aches
- Carpal tunnel syndrome: rare; documented with high-dose direct GH but uncommon with sermorelin
- Very short half-life (~12 min): multiple daily injections needed for sustained effects; impractical for some users vs longer-acting alternatives
- WADA-prohibited under category S2; all GH secretagogues banned in and out of competition
- US access uncertain: original Geref product discontinued 2008; 503A compounding under FDA review since 2023; research chemical sources have standard quality concerns
Key facts
Key facts worth knowing
- Sermorelin is a 29-amino acid synthetic analog of human GHRH (specifically the GHRH 1-29 fragment). The first 29 amino acids of the 44-amino acid native GHRH retain essentially full biological activity.
- FDA-approved 1990 under brand name Geref by EMD Serono, primarily for diagnosing growth hormone deficiency (where blunted response to sermorelin indicates pituitary-level dysfunction). Also used therapeutically for GH deficiency in children.
- Original commercial product withdrawn in 2008 by EMD Serono for business reasons: the development of recombinant human GH (somatropin) had largely displaced GHRH-based diagnostics, making continued production commercially uneconomical. The withdrawal was not for safety concerns.
- Currently available through compounding pharmacies in the United States (under 503A/503B exemptions) and unregulated sources. As of 2026, the regulatory landscape for compounded peptides has been progressively tightening.
- Very short half-life (~12 minutes) is the major pharmacological limitation: produces a brief GH pulse rather than sustained elevation; theoretically more physiological (mimicking natural pulsatile GHRH release); less convenient than longer-acting alternatives.
- Modified GRF (1-29) is a tetrasubstituted variant of sermorelin (substitutions at positions 2, 8, 15, and 27) that extends half-life to at least 30 minutes. Commonly sold separately as "Mod GRF 1-29", frequently confused with CJC-1295 No DAC which is the same compound.
- Mechanism is GHRH receptor agonism on pituitary somatotrophs, producing endogenous GH release while preserving normal feedback mechanisms (unlike exogenous GH which suppresses endogenous production). Acts at a different receptor from the GHRPs such as ipamorelin, which bind GHS-R (the ghrelin receptor); the older literature documents a larger GH pulse from combined stimulation of the two pathways than from either alone.
- WADA status: Prohibited under category S2 (peptide hormones, growth factors, and related substances) of the Prohibited List. All GH secretagogues are banned both in and out of competition.
Legal status
Legal status
Was FDA-approved (1990); commercial Geref product discontinued 2008 for business reasons. Available through 503A/503B compounding pharmacies (under FDA review since 2023) and unregulated sources. Not a controlled substance. WADA-prohibited under category S2.