Ipamorelin
Ipamorelin is a selective growth hormone releasing peptide (GHRP), a synthetic pentapeptide that binds to the ghrelin receptor (GHS-R1a) in the pituitary gland, triggering the release of growth hormone (GH). It was developed in the 1990s by Novo Nordisk and studied extensively in clinical trials for GH deficiency and wasting conditions, though it was ultimately not commercialized in favor of other compounds.
- class
- GHRP (GH releasing peptide)
- route
- subcutaneous
- cadence
- 1–3× daily (fasted preferred)
- storage
- refrigerated · 28-day max
- typical dose
- 100–300 mcg per injection
- cycle
- 8–16 weeks, then 4-week break
What is Ipamorelin?
Ipamorelin is a selective growth hormone releasing peptide (GHRP), a synthetic pentapeptide that binds to the ghrelin receptor (GHS-R1a) in the pituitary gland, triggering the release of growth hormone (GH). It was developed in the 1990s by Novo Nordisk and studied extensively in clinical trials for GH deficiency and wasting conditions, though it was ultimately not commercialized in favor of other compounds.
What distinguishes ipamorelin from earlier GHRPs (like GHRP-2 and GHRP-6) is its selectivity. Ipamorelin produces GH release with minimal or no elevation of cortisol, prolactin, or ACTH, hormones that older GHRPs significantly elevated. This cleaner hormonal profile means fewer side effects (no increased hunger, no cortisol-related consequences) while still achieving robust GH pulses. This selectivity is why ipamorelin became the preferred GHRP in anti-aging and performance research.
Ipamorelin works best when combined with a growth hormone releasing hormone (GHRH) analog. The most common combination is ipamorelin + CJC-1295 (without DAC, the modified GRF 1-29 form). CJC-1295 extends the GHRH signal from the hypothalamus while ipamorelin amplifies pituitary GH release, together they produce a synergistic GH pulse significantly larger than either agent alone. The two are typically injected together, either as a blend or back-to-back using the same syringe needle.
Timing is critical for ipamorelin. Growth hormone is released in pulses throughout the day, with the largest natural pulse occurring shortly after sleep onset. Injecting ipamorelin (with or without CJC-1295) 30–60 minutes before sleep amplifies this natural overnight pulse and avoids interfering with other hormones. Pre-workout injection is the second most common timing. Critically, ipamorelin must be injected in a fasted state, eating (especially carbohydrates and fat) raises insulin and somatostatin, which blunts or eliminates the GH pulse.
Effects reported in research protocols include improved body composition (lean mass gains, gradual fat reduction), better sleep quality (GH is essential for deep sleep architecture), faster recovery from training and injury, and improved skin thickness and collagen content. These effects are gradual, typically taking 8–12 weeks to become subjectively noticeable. Ipamorelin is not an anabolic steroid and does not work through androgen receptors, it stimulates the body's own GH production rather than providing exogenous GH directly.