Sermorelin and ipamorelin are both sold to raise the body’s own growth hormone, and both are injected, so they are often weighed against each other. No head-to-head trial turns up in PubMed, which means the honest comparison is between two evidence records: an older approved drug with modest pediatric and small adult data, and a research peptide whose human record is thinner still.
They also differ on this site in a way that follows from those records. Sermorelin is eligible, because its approved product left the market for reasons other than safety. Ipamorelin is research-only, so it gets evidence coverage and nothing more. Sermorelin sits under the sleep goal on this site, and what a peptide is is covered separately.
Two receptors, two mechanisms
Sermorelin is the first 29 amino acids of growth-hormone-releasing hormone, the hypothalamic signal that tells the pituitary to release growth hormone [1]. It acts on the GHRH receptor, the natural route for that signal.
Ipamorelin, five amino acids long, acts on a different receptor, the one targeted by the growth-hormone-releasing peptides [2]. In swine, its distinguishing feature was selectivity: it released growth hormone without raising ACTH or cortisol, even at doses more than 200 times the effective dose, a property that was measured in animals and not established in people.
| Sermorelin | Ipamorelin | |
|---|---|---|
| Receptor | GHRH receptor | Growth-hormone-releasing peptide receptor |
| FDA approval | Yes, as GEREF (1990 and 1997) | None in the sources read |
| Largest human study | 110 children, 1 year, open-label | 117 adults after bowel surgery, up to 7 days |
| Adult data | Two studies, 10 and 11 older men | One dosing study in healthy men |
| FDA compounding status | Compoundable (GEREF basis) | 503B Category 2, safety risks |
What sermorelin’s record shows
In its largest trial, 110 children with growth hormone deficiency took 30 micrograms per kilogram at bedtime for up to a year [3]. Among the 86 analyzed, mean height velocity rose from 4.1 to 7.2 cm a year at 12 months, and no adverse changes in blood chemistry or fasting glucose were seen. In 10 healthy older men, twice-daily 1 mg injections for 14 days raised growth hormone and IGF-1 to the levels of young men [4].
The most common side effects in the clinical record were transient facial flushing and injection-site pain [1]. The full safety picture, and how small it is, is in sermorelin side effects, and the doses the studies used are in sermorelin dosage.
What ipamorelin’s record shows
In healthy men, ipamorelin by infusion produced a single growth hormone pulse that peaked at 0.67 hours, with a drug half-life of about 2 hours [5]. Its one published efficacy trial asked whether it sped up gut recovery after bowel surgery, and it did not: median time to a tolerated meal was 25.3 hours on ipamorelin and 32.6 hours on placebo, p = 0.15 [6]. More is in ipamorelin’s human evidence.
A chart review of a sermorelin combination
A retrospective chart review looked at men on testosterone who were prescribed sermorelin together with GHRP-2 and GHRP-6, three times daily [9]. Of 105 men, only 14 met the strict compliance criteria for analysis, and in them mean IGF-1 rose from 159.5 to 239.0 ng/mL. That is a hormone level in a handful of men on a three-drug combination, not evidence about sermorelin or ipamorelin alone, and it measured no health outcome.
What neither record answers
Neither compound has an adult trial that measured sleep, fat loss or recovery as an outcome; one small sermorelin study measured muscle strength in 11 older men. For the sleep question specifically, the human studies of this hormone family are in peptides for sleep, and the regulatory side is in are peptides legal.