GRF 1-29 · GHRH(1-29)NH₂ · Geref (discontinued)
The first 29 amino acids of endogenous GHRH, the shortest fragment that retains full biological activity at the GHRH receptor. Formerly FDA-approved as Geref for paediatric GH deficiency (1997–2008). The most legally defensible GH peptide for compounding in the US due to its prior FDA approval history. The most commonly prescribed GH secretagogue at hormone optimisation clinics.
01, Research Summary
Sermorelin has a unique regulatory history that distinguishes it from every other research peptide in the GH secretagogue class. It was FDA-approved in 1997 as Geref (EMD Serono) for paediatric growth hormone deficiency. The manufacturer discontinued it in 2008 for commercial reasons, the market for paediatric GH deficiency was small and synthetic GH dominated, not safety concerns. That prior approval history means its safety profile was established through the FDA's regulatory process, giving compounding pharmacies strong legal standing to produce it under 503A.
FDA-approved for paediatric GH deficiency. Sermorelin received full FDA approval with Phase 3 clinical trial data establishing efficacy and safety in growth hormone-deficient children. Discontinued in 2008 for commercial reasons unrelated to safety.
+1.26 kg lean mass in elderly men over 16 weeks. The landmark adult study showed lean mass increases in men (not women) with no significant fat loss or bone density changes. 19 subjects, single-blind, a small but foundational dataset for off-label use.
GHRH analogues restore GH pulsatility and improve lean mass in GH-deficient adults. Confirms the mechanistic case for sermorelin's off-label use in adult GH optimisation, though tesamorelin's 816-patient Phase 3 program represents a significantly stronger evidence base for the same goal.
The adult evidence for sermorelin is thinner than its clinical reputation suggests. The entire body composition case rests primarily on Khorram et al., 19 subjects, 16 weeks, single-blind. Compare this to tesamorelin's Phase 3 program and the evidence gap is significant. Sermorelin earns its position primarily through regulatory clarity, not superior efficacy data.
02, Mechanism of Action
Sermorelin is the first 29 amino acids of endogenous GHRH, the shortest fragment demonstrated to retain full biological activity at the GHRH receptor. It activates the same receptor as CJC-1295 and tesamorelin, but with a shorter half-life (~10–20 minutes) that produces a more physiologically brief GH stimulus.
Sermorelin binds the pituitary GHRH receptor with high specificity, activating adenylate cyclase and cAMP signalling that drives GH synthesis and pulsatile release from somatotrophs. The somatostatin feedback brake remains intact, the pituitary self-regulates GH output.
Sermorelin does not significantly raise cortisol, ACTH, or prolactin at standard doses, a selectivity profile similar to ipamorelin and superior to older GHRPs like GHRP-2 and GHRP-6. This makes it more appropriate for longer-term use without unwanted hormonal side effects.
Pulsatile GH release stimulates hepatic IGF-1 production. Over extended protocols, increased IGF-1 drives the body composition and tissue repair effects associated with restored youthful GH levels, lean mass preservation, visceral fat reduction, and improved recovery.
All three activate the same GHRH receptor. Sermorelin: prior FDA approval, strongest legal position, shortest half-life, thinnest adult evidence. CJC-1295: no FDA history, multiple half-life options (DAC/no-DAC), some clinical data. Tesamorelin: FDA-approved for lipodystrophy, strongest Phase 3 evidence base, highest cost. Sermorelin's regulatory clarity is its primary advantage over CJC-1295; tesamorelin's evidence base is its primary advantage over sermorelin.
03, Dosing Context
Standard sermorelin dosing mirrors the pre-bed protocol of other GH secretagogues, timing to amplify the body's natural nocturnal GH pulse.
| Protocol | Dose | Frequency | Timing | Notes |
|---|---|---|---|---|
| Standard | 200–300 mcg | 5 nights/week | Before bed, fasted | Most common clinical protocol |
| With ipamorelin | 200 mcg each | Daily | Before bed, fasted | Co-inject for synergistic GH pulse |
| Beginner | 100–150 mcg | 5 nights/week | Before bed, fasted | Assess response before escalating |
Expected timeline: improved sleep quality within weeks 1–4, improved recovery and energy by weeks 4–8, modest body composition changes at 3–6 months. Sermorelin's effects build more slowly than direct GH administration, it works through the body's own system rather than overriding it.
Under 2026 compounding regulations, prescribers must document clinical necessity and attempted or contraindicated FDA-approved alternatives before ordering compounded sermorelin from 503B facilities. 503A patient-specific compounding remains accessible with a valid prescription.
04, Community
Sermorelin occupies the clinical-adjacent end of the GH peptide community, used most by people accessing it through hormone optimisation clinics with physician prescriptions, rather than grey-market research sourcing. Community reports generally describe it as the "safer but slower" GH option: less dramatic than exogenous HGH, fewer side effects, longer timeline to results. The before-bed protocol consistently produces the first noticeable effect, deeper sleep, which many users describe appearing within the first 1–2 weeks.
A common community observation is that sermorelin's effects are more sustainable than more aggressive GH protocols: gradual lean mass preservation and fat reduction without the water retention and side effects associated with higher-dose GH interventions.