The two classes
Almost every compound marketed as a "GH peptide" falls into one of two pharmacologic families. They use different receptors, and they're often combined in clinical practice precisely because their mechanisms are complementary.
Class 1
GHRH analogs
Mimic the body's natural growth-hormone-releasing hormone and bind the GHRH receptor on the anterior pituitary.
Sermorelin · CJC-1295 · Tesamorelin
Class 2
Ghrelin / GHS-R agonists
Bind the growth-hormone-secretagogue receptor (GHS-R) — the same receptor the hunger hormone ghrelin uses — to trigger GH pulses.
Ipamorelin · MK-677 (Ibutamoren)
Comparison
Compounds at a glance
| Compound | Class | Mechanism | Half-life | Evidence | Regulatory status |
|---|---|---|---|---|---|
| Sermorelin | GHRH analog | Binds the GHRH receptor on the pituitary to stimulate endogenous GH release | ~10–20 minutes | FDA-approved historically for pediatric GH deficiency (withdrawn from US market 2008); legacy compounded use in adults | Compounded only; not FDA-approved for adult use |
| CJC-1295 (with/without DAC) | GHRH analog | Long-acting GHRH analog; DAC variant binds albumin to extend half-life | ~30 min (no DAC) to ~6–8 days (with DAC) | Small Phase 1/2 trials in healthy adults; not FDA-approved | Removed from FDA 503A bulks list (2023); research-only |
| Tesamorelin | GHRH analog | Stabilized GHRH analog stimulating pituitary GH release | ~25–40 minutes | FDA-approved (Egrifta) for HIV-associated lipodystrophy | FDA-approved for a specific indication |
| Ipamorelin | Ghrelin / GHS-R agonist | Selective ghrelin-receptor agonist that pulses GH release without significant cortisol or prolactin elevation | ~2 hours | Early-phase studies in postoperative ileus; not FDA-approved | Removed from FDA 503A bulks list (2023) |
| MK-677 (Ibutamoren) | Oral ghrelin / GHS-R agonist | Orally bioavailable non-peptide ghrelin mimetic; raises GH and IGF-1 over 24 hours | ~4–6 hours (sustained effect) | Phase 2 trials in elderly adults and hip-fracture recovery; failed to show benefit in Alzheimer's; never FDA-approved | Investigational; not approved; sold illegally as a supplement |
Factual comparison only. No dosing information. Consult a qualified physician.
What the evidence actually shows
The strongest data in this category sits with Tesamorelin: two replicated Phase 3 trials demonstrated reductions in visceral adipose tissue in HIV-associated lipodystrophy, which is the basis of its FDA approval as Egrifta. Outside that indication, the evidence base for GH secretagogues is much thinner than internet claims suggest.
For Sermorelin, CJC-1295, and Ipamorelin, the published literature is mostly small early-phase or pharmacokinetic studies showing the compounds do raise GH and IGF-1. There are no large, replicated trials demonstrating those hormonal changes translate into durable clinical benefits — body composition, recovery, sleep, or longevity — in healthy adults.
MK-677 (Ibutamoren) has the most published trials of the non-approved compounds in this list, including a Phase 2 study in older adults and a hip-fracture recovery study. Despite years of development, no sponsor has brought it to approval, and an Alzheimer's trial failed to show benefit.
Regulatory reality (2023 onward)
In 2023 the FDA removed both Ipamorelin and CJC-1295 from the 503A bulk-substance list, meaning compounding pharmacies in the US can no longer legally compound them under that pathway. They are still widely available from research-chemical vendors, but that channel is unregulated for human use. Tesamorelin remains the only GH secretagogue with an active FDA approval.
Side effects to know about
- Injection-site reactions (all injectable peptides)
- Water retention and mild edema, especially with MK-677
- Increased appetite — a direct ghrelin-receptor effect
- Mild fasting-glucose elevation and reduced insulin sensitivity
- Theoretical long-term concern: chronically elevated IGF-1 has been associated with increased risk for several cancers in observational data. Long-term safety in healthy adults has not been established for any compound in this class.
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Find a ProviderMedical disclaimer: this page is educational and is not medical advice. Growth hormone secretagogues should not be used without supervision from a qualified physician.