Sermorelin

Sermorelin is a synthetic 29-amino-acid peptide analog of endogenous growth hormone releasing hormone (GHRH). It consists of the first 29 amino acids of the 44-amino-acid natural GHRH sequence, the biologically active N-terminal fragment required for GHRH receptor binding and GH stimulation. Sermorelin was FDA-approved in 1997 as Geref for the diagnosis and treatment of growth hormone deficiency in children, giving it the longest clinical track record of any GHRH analog.

As a GHRH analog, sermorelin stimulates the anterior pituitary gland to produce and release growth hormone through the body's own regulatory axis. This is distinct from injecting exogenous recombinant human GH (rhGH), which bypasses the hypothalamic-pituitary axis entirely. Sermorelin preserves the natural pulsatile pattern of GH secretion, the hypothalamus still provides regulatory feedback, preventing unchecked GH elevation and maintaining the safety profile of endogenous pituitary signaling.

Sermorelin has a shorter half-life (~10–20 minutes) and lower potency per microgram compared to CJC-1295 without DAC (~30 minutes), but compensates with its extensive clinical history. Decades of use in compounding pharmacies for anti-aging medicine, pediatric safety data from FDA trials, and physician experience make sermorelin arguably the most clinically grounded GHRH analog available. Physicians specializing in GH optimization often began with sermorelin before newer analogs became available.

Standard compounding pharmacy vials come in 9 mg sizes. Reconstituted with 9 mL of bacteriostatic water, the concentration is 1 mg/mL (1,000 mcg/mL). A 300 mcg dose draws 30 units on a U-100 syringe, a comfortable, precise volume. Inject subcutaneously in the abdomen 30–60 minutes before sleep in a fasted state. The largest natural GH pulse occurs shortly after sleep onset; sermorelin is timed to amplify this pulse. Eating, especially carbohydrates and fats, raises insulin and blocks GH release.

Sermorelin is sometimes combined with a GHRP (such as ipamorelin) in a pre-mixed formulation from compounding pharmacies, though the combination is less extensively studied than the ipamorelin/CJC-1295 pairing. Effects, improved body composition, sleep quality, recovery, and skin collagen, are gradual and typically noticeable after 8–12 weeks. Sermorelin is not approved for anti-aging use and is prescribed off-label by physicians or used as a research peptide outside supervised settings.