Ipamorelin vs GHRP-6

What is the core difference between ipamorelin and GHRP-6?

The core difference is selectivity: ipamorelin was reported to release GH with little effect on cortisol or prolactin, while GHRP-6 acts on a broader set of hormones.

Both peptides are synthetic growth hormone secretagogues. They mimic ghrelin at the GH secretagogue receptor and trigger the pituitary to release stored GH in pulses. In the work that introduced ipamorelin, researchers described it as the first selective GH secretagogue, meaning it raised GH without the parallel spikes in adrenocorticotropic hormone (ACTH), cortisol, and prolactin that were seen with other peptides in the same family, including GHRP-6 (Raun et al., 1998).

GHRP-6 belongs to the earlier generation of these compounds. Its activity at the ghrelin receptor is strong, which is why it is repeatedly associated with a marked appetite signal, a hallmark of ghrelin-pathway stimulation.

Which one causes more appetite and hunger?

GHRP-6 is the one associated with a strong hunger signal, while ipamorelin was characterized as more selective with a milder profile.

Ghrelin is often called the hunger hormone, and compounds that activate its receptor can drive food-seeking behavior. GHRP-6 is repeatedly described in the peptide literature as producing a noticeable increase in appetite. Ipamorelin, by contrast, was designed and reported as a selective secretagogue that raised GH without the broad off-target activity of earlier peptides (Raun et al., 1998).

It is worth being precise here: controlled human appetite data comparing these two peptides head to head is limited. Much of the appetite characterization comes from mechanism and preclinical work rather than large human trials.

How do cortisol and prolactin responses compare?

Ipamorelin was reported to leave cortisol and prolactin largely unchanged, while GHRP-6 in the same research produced increases in those hormones.

This is the most cited distinction between the two. In the foundational study, ipamorelin released GH at levels comparable to GHRP-6 but did not meaningfully raise ACTH, cortisol, or prolactin, whereas GHRP-6 did (Raun et al., 1998). For research purposes, that selectivity is the reason ipamorelin is often grouped with newer, more targeted secretagogues.

For broader class context, sustained GH and IGF-1 elevation has been documented with other secretagogues such as CJC-1295 (Teichman et al., 2006), and the oral agent MK-677 raised fasting glucose and reduced insulin sensitivity in a one-year study (Nass et al., 2008). These findings underline that "raises GH" does not mean "no downstream effects."

Ipamorelin vs GHRP-6 decision table

Here is a side-by-side of what the research reports, framed for study design, not personal use.

What are the reported side effect profiles?

Ipamorelin's selective profile means fewer reported off-target hormone effects, while GHRP-6's broader activity carries more of them, including appetite and cortisol changes.

Because ipamorelin was reported to avoid cortisol and prolactin spikes, its side-effect discussion centers on the general secretagogue class rather than hormone crossover (Raun et al., 1998). GHRP-6, with its wider activity, adds the appetite response and hormone shifts to that picture.

Across the whole GH secretagogue class, the more important caution is metabolic. In a one-year trial of the oral secretagogue MK-677, fasting glucose rose and insulin sensitivity fell (Nass et al., 2008). While that is a different molecule, it illustrates that raising GH signaling can affect glucose handling, a class-level consideration researchers track.

What dose ranges has the research reported?

Published characterization of these peptides comes largely from mechanistic and preclinical work, not standardized human dosing trials, so no clinician-style regimen exists in the literature.

The foundational ipamorelin work established selectivity and GH-release behavior in preclinical models rather than defining a human treatment dose (Raun et al., 1998). Because completed, large human dosing trials for both ipamorelin and GHRP-6 are limited, this page does not list a milligram protocol. Any decision about amount, timing, or combination is a clinical judgment that belongs with a qualified prescriber who can weigh individual factors and monitoring.