A cluster of research peptides act on growth hormone release rather than supplying growth hormone directly. They divide into two mechanisms, and their evidence bases are weaker than their marketing suggests.
Two routes to the same axis
- GHRH analogues copy growth-hormone-releasing hormone, the hypothalamic signal that tells the pituitary to release growth hormone. Sermorelin, CJC-1295 and tesamorelin work this way.
- Ghrelin receptor agonists act on a separate receptor that also triggers growth hormone release. Ipamorelin is the common example.
Because the routes differ, they are often sold combined. The rationale is reasonable theory; it has not been tested in a published human trial.
What has actually been established
| Compound | Human evidence | Status |
|---|---|---|
| Tesamorelin | Phase 3 trials in HIV-associated lipodystrophy | FDA-approved for that use |
| Sermorelin | Approved 1997 for paediatric growth hormone deficiency | Discontinued 2008 for business reasons |
| CJC-1295 | Early studies confirming raised GH and IGF-1 | Development stopped; never approved |
| Ipamorelin | Early trials including post-surgical bowel function | Development stopped; never approved |
Note what the CJC-1295 and ipamorelin entries say. Those studies established that the molecules do what they were designed to do pharmacologically. They did not establish that doing so improves body composition, recovery, sleep or ageing.
With DAC and without
CJC-1295 is sold in two forms that behave very differently. With DAC it binds to albumin and persists for days. Without DAC, often sold as Mod GRF 1–29, it lasts minutes. They are not interchangeable, and material sold online is not always clear about which is which.
What raising growth hormone long-term might do
Sustained elevation of growth hormone and IGF-1 carries recognised theoretical concerns: fluid retention, joint pain, carpal tunnel symptoms and insulin resistance, all documented in growth hormone excess. Epidemiological research also links sustained high IGF-1 with increased risk of some cancers.
None of these compounds has long-term human safety data, because the trials that would produce it were never run. IGF-1 and its analogues are also on the World Anti-Doping Agency’s prohibited list.