Peptides vs HGH: How Secretagogues Differ From Growth Hormone

Human growth hormone is a 191-amino-acid protein made by the anterior pituitary, and it is not released steadily. The hypothalamus sends two opposing signals — growth hormone-releasing hormone (GHRH), which promotes release, and somatostatin, which restrains it — and the result is a series of pulses, the largest arriving in slow-wave sleep. A 2000 paper in JAMA that studied 149 healthy men across adulthood reported that slow-wave sleep and the growth hormone secreted during it both fall steeply between young adulthood and midlife. Growth hormone acts largely through insulin-like growth factor 1 (IGF-1), which the liver makes in response; IGF-1 integrates the pulses into a steadier number and feeds back to damp further release, which is why it is the marker physicians track.

Recombinant somatropin (Genotropin, Norditropin, Humatrope, Omnitrope) is that same protein manufactured in engineered cells. Once injected it delivers growth hormone at whatever level the dose sets; the pituitary is not involved and the pulse is replaced by an injected level.

The approved uses are narrow and named. The current Genotropin prescribing information indicates somatropin in children for growth failure due to growth hormone deficiency, Prader-Willi syndrome, being born small for gestational age without catch-up growth by age two, Turner syndrome, and idiopathic short stature meeting a defined height threshold; and in adults for replacement in growth hormone deficiency of adult onset (from pituitary or hypothalamic disease, surgery, radiation or trauma) or of childhood onset. The label states that confirming adult deficiency involves a growth hormone provocative test, with only two exceptions. A low IGF-1 on a wellness panel is not a diagnosis, and age-related decline in a healthy adult is not on the list.

The Genotropin label contraindicates somatropin in active malignancy, acute critical illness after major surgery or trauma, severe diabetic retinopathy, known hypersensitivity, and growth promotion in children whose growth plates have closed. Its warnings cover progression or recurrence of pre-existing tumors, glucose intolerance and diabetes that may be unmasked, intracranial hypertension, fluid retention presenting as edema, joint pain and carpal tunnel syndrome ("especially in adults"), hypothyroidism and adrenal insufficiency becoming evident, and pancreatitis; it directs periodic glucose monitoring in all patients. Endocrinologists titrate a daily subcutaneous dose against IGF-1 and those side effects.

The reason anyone asks about growth hormone for aging is a 1990 paper in the New England Journal of Medicine in which Rudman and colleagues gave somatropin to twelve men over sixty with low IGF-1 for six months and reported more lean mass and bone density and less adipose mass than in nine untreated controls. It was small, unblinded and short, and did not measure strength or function. A 2007 systematic review in Annals of Internal Medicine pooled 31 studies in healthy elderly people — 220 treated participants, a mean of 27 weeks — and reported small body-composition changes, no consistent improvement in strength, bone density, lipids or fitness, and significantly more edema, joint pain, carpal tunnel syndrome and gynecomastia. Its conclusion was that growth hormone cannot be recommended as an anti-aging therapy.

Federal law is explicit. 21 U.S.C. § 333(e) makes it a crime to knowingly distribute, or possess with intent to distribute, human growth hormone "for any use in humans other than the treatment of a disease or other recognized medical condition, where such use has been authorized by the Secretary of Health and Human Services under section 355 of this title and pursuant to the order of a physician." The offense carries up to five years' imprisonment, ten where a person under eighteen is involved. Subsection (e)(4) defines "human growth hormone" as "somatrem, somatropin, or an analogue of either of them."

The definition covers growth hormone and its analogues; sermorelin, CJC-1295 and tesamorelin are analogues of GHRH, the releasing hormone, and ipamorelin is a ghrelin mimetic. None is growth hormone or an analogue of it, which is why the two sit under different legal frameworks.

Every peptide here acts on the pituitary rather than replacing its output, and there are two ways in. The GHRH receptor is the native target of growth hormone-releasing hormone; sermorelin, CJC-1295 and tesamorelin are modified versions of GHRH that bind it. The growth hormone secretagogue receptor is the receptor for ghrelin; ipamorelin and hexarelin are synthetic ghrelin mimetics that bind it. A 1995 paper in Clinical Endocrinology reported a larger response from the two classes together than from either alone, the basis for pairing them. Whichever receptor is used, the gland does the releasing, somatostatin can still restrain it, and IGF-1 can still feed back.

Sermorelin is the first 29 amino acids of GHRH, the shortest fragment that fully activates the receptor. It was the active ingredient of Geref, approved by the FDA in 1990 as a diagnostic test of pituitary reserve and in 1997 for growth hormone deficiency in children. The pivotal trial, in the Journal of Clinical Endocrinology and Metabolism in 1996, gave 110 children once-daily bedtime injections for up to a year and reported roughly doubled height velocity with fasting glucose unchanged. In adults, two randomized trials — Neurobiology of Aging in 2006 and Archives of Neurology in 2012 — reported that twenty weeks of daily GHRH(1-29) improved cognitive test scores in healthy older adults and in adults with mild cognitive impairment. Sermorelin is short-acting, given at bedtime, and described by prescribers as the gentlest starting point. Reference: what is sermorelin.

CJC-1295 is GHRH(1-29) with four substitutions that protect it from the enzyme that breaks GHRH down within minutes; the form compounded here is the version without the "drug affinity complex," so it acts over hours rather than a week. A 2006 study in the Journal of Clinical Endocrinology and Metabolism reported growth hormone and IGF-1 rising for days after a dose in healthy adults, and a companion paper the same year reported that the pituitary's pulsatile release persisted during continuous stimulation — larger pulses, same rhythm. There are no randomized outcome trials of CJC-1295 for any wellness endpoint; the evidence is pharmacology plus prescriber experience. It is supplied as CJC-1295 / Ipamorelin; see what is CJC-1295 / ipamorelin and CJC-1295 vs sermorelin.

Ipamorelin is a five-amino-acid ghrelin mimetic. The paper that introduced it, in the European Journal of Endocrinology in 1998, described it as the first growth hormone secretagogue that released growth hormone without a measurable rise in cortisol, ACTH or prolactin in animal models. A 1999 paper in Pharmaceutical Research modeled its growth hormone response in human volunteers. Its only randomized human trial was unrelated to aging: a 2014 study in the International Journal of Colorectal Disease tested intravenous ipamorelin for recovery of bowel function after surgery. Ipamorelin is the ghrelin-side partner in CJC-1295 / Ipamorelin, is available alone as ipamorelin, and is described at what is ipamorelin.

Tesamorelin is the full 44-amino-acid GHRH with a modification that slows its breakdown, and it is the one peptide in this class with an FDA-approved product on the market: Egrifta, for the reduction of excess abdominal fat in adults with HIV who have lipodystrophy. The Egrifta SV label states that long-term cardiovascular safety has not been established and that it is not indicated for weight-loss management because its effect on weight is neutral. Its evidence is randomized and placebo-controlled: the phase 3 program in the New England Journal of Medicine in 2007 and the Journal of Acquired Immune Deficiency Syndromes in 2010, measuring visceral adipose tissue by CT, and a 2012 trial in obese adults without HIV who had reduced growth hormone secretion. Compounded tesamorelin is prescribed off-label for goals outside that indication, which is an extrapolation; see what is tesamorelin.

Hexarelin is an older ghrelin mimetic with a large 1990s human pharmacology literature; it is less selective than ipamorelin — 1997 papers in Peptides and the Journal of Clinical Endocrinology and Metabolism reported it also raised prolactin, ACTH and cortisol — and hexarelin sits in the same feedback-intact category, with ipamorelin the usual first choice. IGF-1 LR3 does not belong in this category at all: IGF-1 LR3 is a modified IGF-1, the downstream growth factor, engineered to escape the binding proteins that buffer it. Supplying IGF-1 LR3 bypasses the pituitary as supplying growth hormone does, and IGF-1 has insulin-like effects on blood sugar.

Somebody with pituitary disease, a pituitary tumor treated with surgery or radiation, or a childhood deficiency carried into adulthood belongs with an endocrinologist, and where a provocative test confirms deficiency the correct treatment is somatropin under its approved indication. A secretagogue is the wrong tool for that person, and Pepti's assessment will say so.

The person this page is mostly for is an adult in their forties or beyond with a working pituitary, a flattening IGF-1, worse sleep and slower recovery than a decade ago, and no diagnosable disease. Growth hormone is not lawfully available for that person, and the trial evidence for it in healthy older adults is not encouraging. A GH-axis peptide is what a physician can actually consider: sermorelin as the gentlest single agent, or CJC-1295 / Ipamorelin as the standard two-receptor pairing. Where the goal is abdominal visceral fat, tesamorelin is the peptide with that endpoint in its randomized trials. Where sleep is the primary complaint, the SERENITY blend pairs CJC-1295 and ipamorelin with DSIP and selank. For more than one goal in one injection there are the combined vials, ASCEND, TITAN, Ipamorelin + Sermorelin and Tesamorelin + Ipamorelin. Which, if any, is appropriate is a physician's decision after labs.

A secretagogue's value is that it works through a responsive pituitary; supplying growth hormone on top raises IGF-1, which suppresses the pituitary's own release, so the peptide has progressively less to act on. Within the peptide class the opposite applies: a GHRH analogue and a ghrelin mimetic act on different receptors of the same cell and are described as additive, which is why CJC-1295 and ipamorelin, or sermorelin and ipamorelin, are paired in one vial.

Somatropin is an FDA-licensed biologic with the indications listed above. Its distribution for any use other than an FDA-authorized indication on a physician's order is a federal offense under 21 U.S.C. § 333(e). A site offering growth hormone for anti-aging or body composition is not offering a legal product, and Pepti does not prescribe it.

Sermorelin acetate was the active ingredient of Geref, held by EMD Serono under NDA 19-863 (diagnostic, 1990) and NDA 20-443 (treatment, 1997). Both are listed in Drugs@FDA as discontinued, each annotated that the FDA determined in the Federal Register that the product was not withdrawn for safety or effectiveness reasons. Sermorelin does not appear in Category 1, 2 or 3 of the FDA's list of bulk drug substances nominated for compounding under section 503A, updated 14 May 2026, was not among the peptides removed from Category 2 on 15 April 2026, and was not on the agenda of the Pharmacy Compounding Advisory Committee's 23–24 July 2026 meeting. Compounded sermorelin is not an FDA-approved product.

Both were placed in Category 2 of the interim 503A list in 2023 and left it in September 2024 when their nominations were withdrawn and the FDA referred them to its advisory committee. On 29 October 2024 the Pharmacy Compounding Advisory Committee considered ipamorelin (free base) and ipamorelin acetate, evaluated for growth hormone deficiency and postoperative ileus, and voted 0 yes, 12 no, 1 abstain on each, against recommending them for the 503A Bulks List for lack of safety and efficacy data for those uses. On 4 December 2024 the committee considered the CJC-1295 family, evaluated for growth hormone deficiency, and voted 0 yes, 13 no on CJC-1295 (free base), 1 yes, 12 no on CJC-1295 acetate, and 0–13 on each DAC form.

Those are advisory votes; the FDA has not issued a final determination. On the 503A list updated 14 May 2026, neither CJC-1295 nor ipamorelin appears in any category. The FDA's safety-risks page, current as of 22 April 2026, lists CJC-1295 among substances "nominated but withdrawn." Neither was on the July 2026 agenda, and neither is among the five substances the committee will review before the end of February 2027. They are prescribed by physicians and compounded to those prescriptions, and they are not FDA-approved drug products.

Egrifta SV (tesamorelin) is licensed under BLA 022505 for excess abdominal fat in adults with HIV and lipodystrophy. Because tesamorelin is the active ingredient of an approved product it was never nominated for the 503A bulks list and does not appear on the 14 May 2026 list in any category. Compounded tesamorelin is prepared to an individual prescription, is not Egrifta, and is not FDA approved; prescribing it outside HIV-associated lipodystrophy is off-label.

Compounded medications are prepared by a state-licensed pharmacy for an individual patient against a physician's prescription and are not reviewed by the FDA as finished products. That is a different statement from "illegal" — they are lawfully prescribed and dispensed — and a different statement from "safe." The pharmacy's licensure, its FDA registration and the certificate of analysis for each batch stand behind the product; see quality and lab results.

The World Anti-Doping Agency's 2026 Prohibited List, in force from 1 January 2026, prohibits at all times under section S2 growth hormone, growth hormone-releasing factors including GHRH and its analogues (it names CJC-1295, sermorelin and tesamorelin), growth hormone secretagogues including ghrelin mimetics (it names ipamorelin and hexarelin), and IGF-1 and its analogues. A tested athlete cannot use either side of this comparison. See do peptides show up on a drug test.