HGH Peptides: How Growth Hormone Secretagogues Work

HGH peptides are not human growth hormone. The term is shorthand for peptides that signal the pituitary gland to release more of the body's own growth hormone, known scientifically as growth hormone secretagogues. They fall into two families that work through different receptors, and their regulatory status ranges from FDA-approved medicine to unapproved research compound. This guide explains how HGH peptides work, how they differ from HGH itself, what the research shows, and the safety and legal facts researchers should know.

Quick answer: HGH peptides stimulate natural growth hormone release instead of supplying the hormone directly. GHRH analogues (sermorelin, CJC-1295, tesamorelin) act on the growth hormone-releasing hormone receptor, while growth hormone-releasing peptides (ipamorelin, GHRP-2, GHRP-6, hexarelin) act on the ghrelin receptor. In the United States, tesamorelin is the only one currently approved as a treatment, for excess abdominal fat in people with HIV-associated lipodystrophy. The rest are unapproved, several are flagged by the FDA for safety risks, and all are prohibited in sport.

What is human growth hormone?

Human growth hormone (HGH, or somatotropin) is a protein of 191 amino acids made by the pituitary gland at the base of the brain. It is released in pulses, with the largest pulse usually coming during deep sleep, and its output declines steadily with age. Much of its effect on tissues is carried out by IGF-1 (insulin-like growth factor 1), which the liver produces in response to growth hormone.

Two hypothalamic hormones control how much growth hormone the pituitary releases:

• GHRH (growth hormone-releasing hormone) switches release on.
• Somatostatin switches it off.

A third signal, the stomach hormone ghrelin, also stimulates growth hormone release through its own receptor, the growth hormone secretagogue receptor (GHS-R). Rising IGF-1 then feeds back to slow the system down. HGH peptides work by acting on one of these control points.

Recombinant HGH is a prescription medicine. A 2025 clinical review in Frontiers in Aging notes that the FDA has approved it in adults for only three indications: growth hormone deficiency caused by pituitary tumors or their treatment, HIV-associated muscle wasting, and short bowel syndrome. The review concludes that it is not advised for anti-aging purposes in healthy older people.

The two types of HGH peptides

Because the two families act through different pathways, researchers have long studied them together. A review of growth hormone secretagogues in Sexual Medicine Reviews describes how ghrelin-receptor agonists and GHRH can act synergistically, and notes that secretagogues stimulate growth hormone release while leaving the body's normal negative feedback from somatostatin and IGF-1 in place.

GHRH analogues

Sermorelin

Sermorelin is a synthetic copy of the first 29 amino acids of natural GHRH, the part of the hormone responsible for its activity. It was once sold as a prescription medicine under the brand name Geref. The product was later discontinued, and in 2013 the FDA published a Federal Register determination that Geref was not withdrawn from sale for reasons of safety or effectiveness. Sermorelin is no longer sold under the Geref brand. See our sermorelin research listing.

CJC-1295

CJC-1295 is a modified GHRH analogue. The version with DAC (drug affinity complex) binds to albumin in the blood, which greatly extends how long it lasts. In a study in healthy adults published in the Journal of Clinical Endocrinology & Metabolism, a single injection raised average growth hormone levels two- to ten-fold for six days or more and IGF-1 levels 1.5- to three-fold for 9 to 11 days, with an estimated half-life of 5.8 to 8.1 days. The version without DAC, often called modified GRF (1-29), lacks this albumin link and is much shorter-acting. CJC-1295 has never been approved as a medicine, and the FDA reports serious adverse events associated with it, including increased heart rate. See CJC-1295 and CJC-1295 without DAC.

Tesamorelin

Tesamorelin is a GHRH analogue approved by the FDA in November 2010, under the brand name Egrifta, to reduce excess abdominal fat in adults with HIV-associated lipodystrophy. According to the FDA's summary review, approval was based on two placebo-controlled trials in which treated patients lost more abdominal fat, measured by CT scan. Its label states that it is not indicated for weight loss. See tesamorelin.

Growth hormone-releasing peptides (GHRPs)

GHRPs are synthetic peptides that activate the ghrelin receptor. Most were developed in the 1980s and 1990s, before ghrelin itself was discovered.

• GHRP-6: one of the first GHRPs. Like ghrelin, it strongly increases appetite. See GHRP-6.
• GHRP-2 (pralmorelin): a more potent GHRP, studied in Japan as a diagnostic agent. See GHRP-2.
• Hexarelin (examorelin): a potent GHRP whose growth hormone response weakens with repeated exposure in studies. See hexarelin.
• Ipamorelin: a pentapeptide described in research as more selective, with less effect on cortisol and prolactin than earlier GHRPs. See ipamorelin.

Two non-peptide ghrelin-receptor agonists are often grouped with these. MK-677 (ibutamoren) is an oral small molecule, not a peptide, despite how it is often marketed. Macimorelin (Macrilen) is an oral ghrelin-receptor agonist approved by the FDA in December 2017, not as a treatment but as a test to help diagnose adult growth hormone deficiency.

HGH vs HGH peptides

What the research shows

Secretagogues reliably raise growth hormone and IGF-1 levels, but evidence that this improves outcomes people care about is limited. The Sexual Medicine Reviews analysis concluded that there are few long-term, rigorously controlled studies, that the literature supports an increased risk of high blood sugar with secretagogue use, and that data on cancer incidence and mortality are lacking.

The longest controlled trial is of MK-677. In a two-year randomized trial in the Annals of Internal Medicine, 65 healthy adults aged 60 to 81 took MK-677 or a placebo daily. Growth hormone and IGF-1 rose to levels typical of young adults, and fat-free mass increased by 1.1 kg compared with a 0.5 kg fall on placebo. The extra lean mass did not improve strength or function, while fasting blood glucose rose, insulin sensitivity fell and appetite increased. Our guide to peptides for muscle growth puts these results in the context of other muscle research.

HGH Fragment 176-191 is not a secretagogue

HGH Fragment 176-191 and the related compound AOD-9604 are pieces of the end of the growth hormone molecule. They do not stimulate growth hormone release and were studied for their effects on fat metabolism instead. AOD-9604 was developed as an obesity treatment but did not become an approved medicine. We cover these fragments in our guide to peptides for weight loss.

Safety and regulation

• FDA safety concerns: The FDA's list of bulk drug substances that may present significant safety risks places ipamorelin, GHRP-2, GHRP-6 and ibutamoren in category 2 of its compounding policy. It cites possible immune reactions, reports of serious adverse events with GHRP-2, safety concerns including a potential effect on cortisol with GHRP-6, and a potential for congestive heart failure in certain patients with ibutamoren.
• Banned in sport: The World Anti-Doping Agency Prohibited List for 2026 prohibits growth hormone-releasing factors at all times, naming GHRH analogues (CJC-1295, sermorelin and tesamorelin), secretagogues (including ipamorelin, ibutamoren and macimorelin) and GHRPs (including hexarelin, GHRP-2 and GHRP-6). Growth hormone fragments such as AOD-9604 and hGH 176-191 are also prohibited.
• Quality: Peptides sold outside regulated pharmaceutical channels are not checked by any regulator, so identity and purity depend on the supplier's own testing.

Roids & Peps lists sermorelin, CJC-1295, ipamorelin, tesamorelin and related compounds in our cellular growth signaling research area strictly as laboratory research materials. They are not sold for human use, and no dosing information is provided. Each batch's certificate of analysis is published in our COA library, and our testing process explains what each test confirms. Anyone with concerns about growth hormone levels should see an endocrinologist, who can test for deficiency and discuss approved treatment.

Frequently asked questions

What are HGH peptides?

HGH peptides are growth hormone secretagogues: peptides that signal the pituitary gland to release more of its own growth hormone. The two main groups are GHRH analogues such as sermorelin and CJC-1295, and ghrelin-receptor agonists such as ipamorelin and GHRP-6.

Are HGH peptides the same as HGH?

No. HGH is the 191-amino-acid growth hormone protein itself. HGH peptides are much shorter molecules that stimulate natural growth hormone release and need a working pituitary gland to have any effect.

Which HGH peptides are FDA-approved?

Tesamorelin is FDA-approved to reduce excess abdominal fat in people with HIV-associated lipodystrophy. Sermorelin was once approved as Geref but has been discontinued. Ipamorelin, CJC-1295, GHRP-2, GHRP-6 and hexarelin have never been approved as medicines in the United States.

Is MK-677 a peptide?

No. MK-677 (ibutamoren) is an oral small-molecule ghrelin-receptor agonist. It is often sold alongside peptides but is not one.

What is the difference between CJC-1295 and ipamorelin?

CJC-1295 is a GHRH analogue that acts on the GHRH receptor, while ipamorelin is a growth hormone-releasing peptide that acts on the ghrelin receptor. Because they work through different pathways, they are often studied together.

Sources

• Fernández-Garza LE, et al. Growth hormone and aging: a clinical review. Front Aging. 2025.
• Sigalos JT, Pastuszak AW. The safety and efficacy of growth hormone secretagogues. Sex Med Rev. 2018.
• Teichman SL, et al. Prolonged stimulation of growth hormone and IGF-I secretion by CJC-1295 in healthy adults. J Clin Endocrinol Metab. 2006.
• Nass R, et al. Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults. Ann Intern Med. 2008.
• U.S. Food and Drug Administration: Egrifta (tesamorelin) summary review, 2010
• Federal Register: Determination that GEREF (sermorelin acetate) was not withdrawn from sale for reasons of safety or effectiveness (2013)
• U.S. Food and Drug Administration: Certain bulk drug substances for use in compounding that may present significant safety risks
• World Anti-Doping Agency: Prohibited List