Growth hormone peptides are compounds that push the pituitary gland to release more of the body’s own growth hormone, mainly GHRH analogs such as tesamorelin, sermorelin and CJC-1295 with DAC, and ghrelin-receptor agonists such as the oral drug MK-677.[13] Only tesamorelin is currently FDA-approved, for excess belly fat in adults with HIV.[3] Prescription HGH replaces growth hormone directly and is approved for specific conditions such as growth hormone deficiency.[1]

This overview explains how the main groups differ, what the evidence shows for each compound we cover, and where the legal and sports-rule lines sit. Each compound has its own detailed profile, linked below.

What are growth hormone peptides?

Growth hormone is made by the pituitary gland, and many of its effects run through a second hormone, IGF-1.[1] The pituitary has two main “release” switches. One is the receptor for growth hormone-releasing hormone (GHRH). The other is a separate receptor first targeted by synthetic growth hormone-releasing peptides (GHRPs) and now known as the ghrelin receptor, after the hunger hormone that also acts on it.[9][10]

Growth hormone peptides copy one of those signals. That makes them different from HGH itself, which is the finished hormone, and from IGF-1 analogs, which skip the pituitary entirely.[13] In practice the label “growth peptide” is also stretched to cover muscle-building compounds that do not touch growth hormone at all, such as PEG-MGF and ACE-031. We include them here because people search for them alongside the others, but they work differently.

Browse all growth peptides

See all 12 growth peptides ↓

How growth hormone peptides work

GHRH analogs bind the GHRH receptor on the pituitary and make it release growth hormone, which then raises IGF-1. Sermorelin is the first 29 amino acids of natural GHRH. Tesamorelin is the full 44-amino-acid hormone with a fatty chain that slows its breakdown, though it still lasts only about 11 minutes in blood.[3] CJC-1295 with DAC binds to albumin, the main blood protein, so a single injection raised growth hormone for 6 days or more and IGF-1 for up to 11 days in healthy adults.[7]

Ghrelin-receptor agonists act on a second switch. Ipamorelin, a small injected peptide, was described in 1998 as the first selective one: in pigs, it raised growth hormone without the rise in the stress hormones ACTH and cortisol seen with the older peptides GHRP-2 and GHRP-6.[8] MK-677 hits the same receptor but is a non-peptide molecule that works when swallowed, which allows once-daily oral dosing.[9][10]

Because both groups rely on the pituitary, they keep some of the body’s natural feedback: rising IGF-1 tends to damp further release.[12] They cannot work if the pituitary has been damaged or removed, which is why tesamorelin’s label rules out that group.[3]

GHRH vs GHRP vs HGH

The three approaches are often lumped together, but they differ in where they act, how they are taken and what has been proven.

GHRH analogsGhrelin-receptor agonists (GHRPs)HGH
ExamplesTesamorelin, sermorelin, CJC-1295Ipamorelin, MK-677 (oral)Somatropin brands
Where it actsGHRH receptor in the pituitaryGhrelin receptor in brain and pituitaryGrowth hormone receptor throughout the body
Needs a working pituitaryYesYesNo
Approved productTesamorelin (Egrifta)None for treatment (macimorelin, Macrilen, is approved only as a diagnostic test)[25]Several brands

GHRH analogs. Tesamorelin has the strongest record: in a phase 3 trial of 412 adults with HIV, it cut deep belly fat by 15.2% in 26 weeks versus a 5% rise on placebo.[4] FDA approved it as Egrifta in 2010.[2] Sermorelin nearly doubled growth rate in children with growth hormone deficiency,[6] was sold as Geref, and was discontinued in 2008; FDA later found it was not withdrawn for safety or effectiveness reasons.[5] CJC-1295 with DAC raised hormone levels in short studies but has no published trials in patients. For the version without DAC, often paired with ipamorelin, see our CJC-1295 and ipamorelin guide.

MK-677. In a two-year trial in 65 adults aged 60 to 81, MK-677 added about 1.1 kg of fat-free mass versus a 0.5 kg loss on placebo, but strength and function did not change, while fasting blood sugar rose and insulin sensitivity fell.[10]

HGH. Daily somatropin brands such as Genotropin are approved for growth hormone deficiency in children and adults and several other growth disorders,[1] and once-weekly versions such as Sogroya followed from 2020.[24] In healthy older adults, a review of 18 study groups found about 2 kg more lean mass and 2 kg less fat, along with more swelling, joint pain and carpal tunnel syndrome.[11]

Muscle growth peptides: PEG-MGF and ACE-031

PEG-MGF is a pegylated copy of a short piece of an IGF-1 variant made in strained muscle. It has never been tested in people.[13] When scientists at two drug companies tried to reproduce the key cell findings for the underlying MGF peptide, it had no apparent effect on muscle cells or muscle stem cells.[14]

ACE-031 is a large fusion protein, not a short peptide, that soaks up myostatin and related muscle-limiting signals. One injection raised lean mass by 3.3% at the top dose in healthy women,[15] but a trial in boys with Duchenne muscular dystrophy was stopped early over nosebleeds and small dilated blood vessels, and its gains were not statistically significant.[16]

Safety, legality and sports rules

Side effects across the growth hormone axis overlap: fluid retention and swelling, joint and muscle pain, tingling or carpal tunnel symptoms, and higher blood sugar appear on the HGH and tesamorelin labels and in MK-677 trials.[1][3][10]

  • Prescription drugs: HGH and tesamorelin are prescription-only.[1][2]
  • Compounding: FDA lists ibutamoren (MK-677) among bulk substances that may present significant safety risks; nominations for CJC-1295 and PEG-MGF were withdrawn.[17] FDA’s advisers voted 1 to 13 against MK-677 and 0 to 13 against CJC-1295 with DAC for compounding in 2024.[19][20] Plain MGF sits on FDA’s 503A list of substances nominated without adequate support.[18]
  • HGH and the law: under 21 U.S.C. 333(e), knowingly distributing HGH, or possessing it with intent to distribute, for any use other than a doctor-ordered treatment of a disease authorized by FDA is a federal crime, with up to 5 years in prison or 10 if a minor is involved.[21] A JAMA review explained why anti-aging HGH falls outside that line.[22]
  • Sport: WADA’s 2026 list bans growth hormone, GHRH analogs, growth hormone secretagogues and mechano growth factors under S2, and ACE-031 under S4, all at all times.[23]

Related categories: hormonal peptides, performance peptides and sleep peptides, where MK-677 also appears.