Sermorelin
GRF 1-29 · Geref · Sermorelin acetate · GHRH(1-29)
GHRH(1-29) — the shortest fully active GHRH fragment, dosed nightly to reinforce the natural GH pulse
Overview
Sermorelin is a synthetic peptide reproducing the first 29 amino acids of growth-hormone-releasing hormone (GHRH), the amino-terminal segment of the native 44-residue hormone and the shortest fragment that retains full biological activity. By binding the GHRH receptor on pituitary somatotrophs it prompts the gland to release its own growth hormone, so the resulting GH rise is still shaped by the body's feedback brakes — chiefly somatostatin — rather than being forced, as it would be with exogenous GH.
Pharmacologically it is short-acting: plasma half-life is roughly 11–12 minutes with rapid clearance (about 2.4–2.8 L/min in adults), so it produces a brief, physiological GH pulse rather than a sustained elevation. That short window is why it is typically injected once nightly, 30–60 minutes before bed and on an empty stomach, to layer onto the largest natural overnight GH pulse. It was originally marketed as Geref for diagnostic GH-stimulation testing and for pediatric growth-hormone deficiency; after Serono discontinued the brand in 2008 it persisted in compounded and research use, and unlike many peptides it was retained on the FDA's compoundable Category 1 list.
Although sermorelin once carried a regulatory approval, no branded product is currently marketed and research-vial material is not a finished pharmaceutical. The figures and schedules below summarize the historical label, the legacy pediatric trial program, and widely-reported adult compounding practice, and are provided strictly as an educational research reference rather than medical advice.
Key parameters
- Dose range
- 100–500 mcg daily (titrated)
- Frequency
- Once daily (usually at bedtime)
- Half-life
- ~11–12 minutes
- Route
- Subcutaneous
- Vial sizes
- 5 mg · 10 mg
- Regulatory status
- Formerly FDA-approved as Geref (1990 for GH-deficiency diagnosis; 1997 for pediatric GH deficiency), discontinued in 2008 for commercial — not safety — reasons. As of 2026 it remains a 503A Category 1 compoundable peptide in the United States, available by prescription through licensed compounding pharmacies; research-vial material is labeled for laboratory use only.
Mechanism of action
GHRH receptor agonism (GHRH(1-29) fragment)
Activates GHRH receptors on anterior-pituitary somatotrophs to stimulate synthesis and pulsatile release of endogenous growth hormone; the 1-29 sequence is the minimal portion of GHRH needed for full receptor activity.
Preserved feedback regulation
Because it works upstream by prompting the pituitary rather than supplying GH directly, the response remains subject to somatostatin's negative feedback, which limits supraphysiologic spikes and is the basis for its comparatively gentle profile.
Downstream IGF-1 elevation
The GH pulse it evokes drives hepatic production of insulin-like growth factor 1 (IGF-1), the principal mediator of the recovery, sleep-quality, and body-composition effects sought from the GH axis; IGF-1 is the usual monitoring marker.
Short, DPP-4-susceptible signal
Unlike modified analogs such as tesamorelin or CJC-1295, the native GRF(1-29) backbone is not protected from enzymatic breakdown, giving the very short half-life and brief duration of action that keep its GH release pulsatile.
Dosing protocol & phases
| Phase | Weeks | Dose | Notes |
|---|---|---|---|
| Initiation | Weeks 1–2 | 100 mcg once nightly | Low starting dose to gauge tolerance and injection-site response; community/compounding practice. |
| Titration | Weeks 3–8 | 200 → 300 mcg once nightly | Stepwise increase, commonly 200 mcg in weeks 3–4 and 300 mcg from week 5; dosed 30–60 minutes before bed on an empty stomach. |
| Maintenance | Week 9 onward | 300–500 mcg once nightly | Some protocols hold at 300 mcg; others go up to 400–500 mcg. Cycles commonly run 3–6 months with IGF-1 monitoring. |
Reconstitution guide
For educational and research reference only. Not intended for human consumption, not medical advice. Compounds discussed are sold and used for laboratory research purposes only.
5 mg vial + 3 mL bacteriostatic water
Concentration1,666.7 mcg/mL · 1.667 mg/mL
| Target dose | Draw volume | U-100 units |
|---|---|---|
| 100 mcg | 0.06 mL | 6 |
| 200 mcg | 0.12 mL | 12 |
| 300 mcg | 0.18 mL | 18 |
Keeps a 100 mcg dose at a readable 0.06 mL (6-unit) draw and a 300 mcg dose at 0.18 mL (18 units).
10 mg vial + 3 mL bacteriostatic water
Concentration3,333.3 mcg/mL · 3.333 mg/mL
| Target dose | Draw volume | U-100 units |
|---|---|---|
| 200 mcg | 0.06 mL | 6 |
| 300 mcg | 0.09 mL | 9 |
| 500 mcg | 0.15 mL | 15 |
Higher-strength mix for a 10 mg vial; the 300–500 mcg maintenance range stays a small, easy draw.
Reconstitution calculator
Pre-filled with Sermorelin's vial sizes. Adjust the water volume and target dose to see the exact draw, with warnings for doses that are hard to measure or won't fit a syringe.
At 1,666.7 micrograms per millilitre, a 100 microgram dose is 0.06 millilitres, or 6 units on a U-100 syringe, giving 50 doses per vial.
Supplies needed
Affiliate disclosure: we may earn a commission from supplier links, at no extra cost to you. For research and educational use only.
Recommended supply
Sermorelin — research vial
From our verified partner Dynotides, with a third-party certificate of analysis per batch.
Injection supplies
- View
Bacteriostatic water
Diluent for reconstituting lyophilized vials.
- Buy
Insulin syringes (U-100)
0.3–0.5 mL, 29–31 G for accurate small draws.
- Buy
Alcohol prep pads
Sterile swabs for the vial stopper and site.
- Buy
Sharps container
Safe disposal of used needles.
- Buy
Storage fridge
Keeps reconstituted vials at 2–8 °C.
- Buy
Insulated travel case
Cooled, TSA-friendly case for travel.
Missed-dose guidance
Because the half-life is only about 11–12 minutes, a missed nightly dose offers no benefit if taken late — skip it and resume the normal schedule the following night rather than doubling up. Timing relative to food matters more than catching up a single dose: a meal (especially carbohydrate or fat) near the injection blunts the GH response, so the dose is taken fasted.
Side effects & safety
| Category | Effect | Trial incidence |
|---|---|---|
| Injection site | Pain, swelling, or rednessRoughly 1 in 6 participants in the legacy pediatric trial program; only 3 of ~350 discontinued for this reason. | 17% |
| Endocrine | Hypothyroidism (developed during therapy)Reported in the FDA-era pediatric trials; baseline and periodic thyroid monitoring is advised. | 6.5% |
| Immunologic | Anti-GRF antibody formationMost pediatric trial patients developed antibodies, but these did not appear to meaningfully reduce sermorelin's effectiveness. | 70% |
| Neurological | Headache, facial flushing, or dizzinessEach reported in under 1% of legacy trial patients; flushing is a brief vasodilatory sensation common to GHRH-class peptides. | — |
| Gastrointestinal | Nausea, vomiting, or altered tasteUncommon (<1%) and generally transient. | — |
| Metabolic | Mild reduction in insulin sensitivityA theoretical GH-class effect with sustained use; glucose and A1c are commonly monitored. | — |
Clinical trials & evidence
Geref pediatric GH-deficiency program
Phase 3 (historical)Up to 36 months · Children with growth-hormone deficiency (~350 patients across the FDA-era diagnostic and treatment trials)
Significant increases in GH and growth velocity were seen by 6 months and maintained through 36 months, supporting the original pediatric approval.
Trial identifier needs verification
GH-stimulation diagnostic use
Diagnostic (historical)Acute · Children and adults undergoing GH-axis testing
Reliably provoked a measurable GH pulse, the basis for sermorelin's original 1990 approval as a diagnostic agent for GH deficiency.
Trial identifier needs verification
Storage & handling
- Lyophilized
- Store the lyophilized powder refrigerated at 2–8 °C and protected from light; for long-term storage −20 °C extends shelf life, while brief room-temperature excursions during shipping are tolerated.
- Reconstituted
- After reconstitution, keep refrigerated and upright at 2–8 °C, protected from light, and use within about 28 days. Do not freeze, and discard if the solution turns cloudy.
Comparisons
| Vs. | Target | Half-life | Dosing | Efficacy | Status |
|---|---|---|---|---|---|
| CJC-1295 (no-DAC) | GHRH (both) | ~11–12 min vs ~30 min | Daily (both) | Native fragment vs a DPP-4-resistant modified backbone that gives a slightly longer, stronger signal | Formerly approved (Category 1 compoundable) vs research-only |
| Tesamorelin | GHRH (both) | ~11–12 min vs ~26–38 min | Nightly vs 2 mg daily | General GH/sleep/recovery support vs label-backed visceral-fat reduction | Formerly approved vs FDA-approved (Egrifta) |
| Ipamorelin | GHRH vs ghrelin/GHS-R | ~11–12 min vs ~2 h | Daily (both) | Different receptor; frequently combined with a ghrelin agonist for additive pulses | Formerly approved vs research-only |
Sources & references
- [1]RxList — Sermorelin Acetate: side effects, dosage, and prescribing summary (legacy Geref data). ↗ source
- [2]Sermorelin — Wikipedia overview of pharmacology and regulatory history (with primary citations). ↗ source
- [3]Strive Pharmacy. Compounded Sermorelin for Clinical Practice: A Practitioner's Guide. ↗ source
Frequently asked questions
Is sermorelin still an approved drug?
It was FDA-approved as Geref but Serono discontinued the brand in 2008 for commercial reasons, not safety. As of 2026 there is no marketed branded product, yet sermorelin remains on the FDA's Category 1 list of compoundable peptides, so it can still be obtained by prescription through licensed compounding pharmacies.
Why is it usually injected at night?
The largest natural GH pulse occurs during early sleep. Dosing a short-acting GHRH fragment 30–60 minutes before bed, on an empty stomach, is intended to reinforce that pulse; eating near the injection — especially carbohydrate or fat — blunts the GH response.
How does sermorelin differ from CJC-1295 or tesamorelin?
All three act on the GHRH receptor, but sermorelin is the plain GRF(1-29) fragment with no stabilizing modification, so it has the shortest half-life (~11–12 minutes) and the most pulsatile, physiological action. CJC-1295 and tesamorelin add modifications that extend their duration and, in tesamorelin's case, deliver a Phase 3-proven visceral-fat effect.
Related protocols
CJC-1295 (no-DAC)
Mod GRF 1-29
Short-acting GHRH analog dosed for natural GH pulses
Tesamorelin
Egrifta
~−15–18% visceral adipose tissue at 26 weeks (pivotal trials)
Ipamorelin
NNC 26-0161
Selective GH pulse with minimal cortisol or prolactin effect
Looking to match this protocol to a verified research vial? Our partner supplier publishes a certificate of analysis per batch.
For educational and research reference only. Not intended for human consumption, not medical advice. Compounds discussed are sold and used for laboratory research purposes only.