CJC-1295 vs Ipamorelin: How the Two Growth Hormone Peptides Differ

Reviewed by Thomas Okafor, PhD · Last reviewed October 22, 2026

CJC-1295 is a modified version of growth hormone-releasing hormone (GHRH) that signals the pituitary through the GHRH receptor. Ipamorelin is a five-amino-acid peptide that signals through a different door, the ghrelin receptor (GHS-R1a). Both led to growth hormone release in studies, by separate routes, which is exactly why they’re so often discussed together. Key takeaways:

• 👤 CJC-1295 raised growth hormone and IGF-1 for days after single injections in two small, short trials in healthy adults.
• 🐭 Ipamorelin released growth hormone in rats and pigs without raising stress hormones such as cortisol, and 👤 its main human trial studied post-surgery gut function.
• 👤 The combination hasn’t appeared in any published human trial. The pairing logic comes from physiology studies of related peptides.
• 🏛️ Neither is FDA-approved, and both appear on the FDA’s compounding safety-risk page.

Both compounds are sold for laboratory research use only and aren’t intended for human consumption. Our Medical Disclaimer explains what that means.

Quick Comparison Table

The two peptides differ at nearly every level, from receptor to research history:

The Growth Hormone Axis in Simple English

Growth hormone release works like a building with two “go” buttons and one “stop” button.

• The first go button is GHRH, made in the hypothalamus at the base of the brain. It travels to the pituitary gland and tells it to release growth hormone.
• The second go button is the ghrelin receptor on pituitary cells. Ghrelin, a hormone best known for signaling hunger, also pushes growth hormone release through this receptor.
• The stop button is somatostatin, also from the hypothalamus, which damps release.

Growth hormone then travels to the liver, which makes IGF-1, the hormone most studies measure as a downstream marker. Release normally happens in pulses, mostly during sleep. The system also regulates itself. Rising growth hormone and IGF-1 signal back to the hypothalamus, which responds by releasing more somatostatin and less GHRH. That feedback loop is why researchers care whether a compound preserves natural pulses or flattens them into a constant signal, and why studies track trough levels between pulses as well as peaks. As Ionescu and Frohman put it, “pulsatile GH secretion is considered important for many of the hormone’s physiological effects.” Having two separate go signals is what makes the CJC-1295 and ipamorelin comparison interesting. CJC-1295 presses the first button. Ipamorelin presses the second. Physiology research suggests pressing both at once produces more than the sum of each alone, a point covered in the combined stack section below.

What Is CJC-1295?

CJC-1295 is a synthetic analog of GHRH, designed to last far longer than the natural hormone. In the version tested in published human trials, a chemical linker lets it bind to albumin in the blood, stretching its half-life from minutes to days. Natural GHRH breaks down within minutes, which limited its research and clinical use. CJC-1295 tackled that by modifying the first 29 amino acids of GHRH, the active portion, and attaching a reactive group that latches onto albumin, the most abundant protein in blood. Our CJC-1295 guide covers its chemistry in more detail.

DAC vs No-DAC (Mod GRF 1-29)

“DAC” stands for Drug Affinity Complex, the albumin-binding part. CJC-1295 with DAC is the version studied in the published human trials, which reported a half-life of 5.8 to 8.1 days. The version without DAC, often sold as “Mod GRF 1-29” or “modified GRF (1-29),” keeps the amino acid changes that resist breakdown but lacks the albumin anchor, so it clears much faster. The two are different molecules, and research on one doesn’t automatically describe the other.

What Human Studies Report

👤 In two randomized, placebo-controlled, double-blind trials published in the Journal of Clinical Endocrinology & Metabolism in 2006, Teichman and colleagues gave CJC-1295 to healthy adults aged 21 to 61, over 28 and 49 days. After a single injection, mean growth hormone rose 2- to 10-fold for six days or more, and IGF-1 rose 1.5- to 3-fold for 9 to 11 days. After repeated injections, IGF-1 stayed above baseline for up to 28 days. 👤 A follow-up study by Ionescu and Frohman in healthy young men found growth hormone kept its natural pulsing pattern after CJC-1295. Trough levels between pulses rose 7.5-fold, mean growth hormone rose 46% and IGF-1 rose 45%. These were small, short studies that measured hormone levels. They didn’t measure muscle, fat, sleep or any other outcome. The Teichman team saw “evidence of a cumulative effect after multiple doses” on IGF-1 and concluded the data “support the potential utility of CJC-1295 as a therapeutic agent,” a door that, so far, no approved product has walked through.

What Is Ipamorelin?

Ipamorelin is a synthetic pentapeptide, a five-amino-acid chain, that activates the ghrelin receptor to release growth hormone. Danish researchers at Novo Nordisk described it in 1998 as the first growth hormone secretagogue with selectivity similar to GHRH, meaning it released growth hormone without raising cortisol in animal tests. 🧪 and 🐭 In the 1998 European Journal of Endocrinology paper introducing it, Raun and colleagues showed ipamorelin released growth hormone from rat pituitary cells and in anesthetized rats and conscious pigs, with potency similar to the older peptide GHRP-6. The surprise came in the pigs: GHRP-6 and GHRP-2 raised ACTH and cortisol, stress hormones, while ipamorelin didn’t, even at amounts more than 200 times higher than those needed for growth hormone release. None of the peptides tested changed FSH, LH, prolactin or TSH. The authors called it “a very interesting candidate for future clinical development.” Our ipamorelin guide covers its background. Why did selectivity get so much attention? Earlier growth hormone-releasing peptides tended to raise cortisol and prolactin alongside growth hormone, which complicated research on them. A compound that released growth hormone alone offered a cleaner tool for studying the ghrelin receptor’s role.

What Human Studies Report

🐭 Before human testing, ipamorelin was studied in rodent models of postoperative ileus, the temporary stall in gut movement after abdominal surgery. Studies by Venkova and colleagues in 2009 and Greenwood-Van Meerveld and colleagues in 2012 reported improved gut motility in rats. 👤 Ipamorelin’s main human program targeted gut motility, because ghrelin-receptor signaling also speeds up the digestive tract. In a phase 2 trial published in 2014, Beck and colleagues gave intravenous ipamorelin or placebo to 114 adults recovering from bowel surgery. The median time to tolerating a solid meal was 25.3 hours with ipamorelin and 32.6 hours with placebo, a difference that wasn’t statistically significant. “There were no significant differences between ipamorelin and placebo in the key and secondary efficacy analyses,” the authors concluded.

How the Two Mechanisms Differ

CJC-1295 acts on the GHRH receptor, the pituitary’s main growth hormone “go” signal, and in the DAC version provides steady, days-long stimulation. Ipamorelin acts on the ghrelin receptor, a second “go” signal, with short-lived effects. Each signal also counters somatostatin’s brake in a different way.

A common simplification is that GHRH sets how much growth hormone pituitary cells are primed to release, while ghrelin-receptor agonists amplify each release and help push back against somatostatin. The exact interplay is still being studied. Picture two arrows pointing into the pituitary from different directions: CJC-1295 is one, ipamorelin the other.

The Combined Stack: Why They Are Paired and What Is Known

CJC-1295 and ipamorelin are paired because GHRH-type and ghrelin-receptor signals act together on growth hormone release in human physiology studies. Those studies used related peptides, though, and no published controlled human trial has tested CJC-1295 with ipamorelin. 👤 The best evidence for the pairing logic comes from Mayo Clinic endocrinologist Johannes Veldhuis and GHRP pioneer Cyril Bowers. In a 2009 study, they infused native GHRH and GHRP-2 together in 47 men and noted that “marked stimulation of pulsatile GH secretion is achieved via GHRH-GHRP synergy.” The strength of that synergy fell with age and with abdominal visceral fat, and rose with IGF-1 levels. Visceral fat, IGF-1 and its binding protein IGFBP-3 together explained 60% of the variation in synergy between the men, under a design that held sex hormones constant. In other words, the same pair of signals produced very different responses in different bodies. That’s evidence that the two pathways work together. It isn’t evidence about the CJC-1295 and ipamorelin pair, which differs in molecules, duration and delivery. A PubMed search on October 22, 2026 returned only review articles discussing the two together, with no trial testing them as a combination. The popular “stack” therefore rests on physiology and extrapolation, with no study of the stack itself behind it.

How They Compare With Sermorelin and Tesamorelin

Sermorelin is a shorter GHRH analog, the first 29 amino acids of natural GHRH. It works through the same receptor as CJC-1295 but without the chemical changes that extend CJC-1295’s life. Our sermorelin guide covers it. Tesamorelin is also a GHRH analog, stabilized in a different way. Unlike CJC-1295, it went through full clinical development and is FDA-approved for one specific use in adults with HIV-associated lipodystrophy, a condition involving abnormal fat distribution. That approval covers that indication only. Our tesamorelin guide explains more. All three act on the GHRH receptor, and ipamorelin is the odd one out, acting through the ghrelin receptor instead. For the wider family, see what peptides are.

Adverse Events Reported in Studies

CJC-1295: What the Human Pharmacology Studies Reported

👤 The 2006 trials reported “no serious adverse reactions.” 🏛️ The FDA’s compounding safety-risk page adds a broader view, stating that “FDA has identified serious adverse events associated with CJC-1295,” including increased heart rate and a systemic vasodilatory reaction, and that “available clinical data are limited.”

Ipamorelin: What the Clinical Trials Reported

👤 In the 2014 phase 2 trial, treatment-emergent adverse events occurred in 87.5% of ipamorelin patients and 94.8% of placebo patients, all of whom were recovering from major bowel surgery. 🏛️ The FDA’s entry notes that “a study published in literature identified serious adverse events including death” when ipamorelin was given intravenously for gastric motility, and that FDA lacks information on other injectable routes.

Unknowns

Long-term effects, effects of the combination, and the content and purity of unregulated research products are all unstudied. A batch certificate of analysis is the main quality check for research material.

Regulatory and Sports Status

As of October 22, 2026, neither CJC-1295 nor ipamorelin is an FDA-approved drug. On the FDA’s compounding safety-risk page:

• CJC-1295 appears among nominations that were withdrawn, with the serious adverse event notes above.
• Ipamorelin acetate remains in Category 2 under the 503B interim policy, added September 29, 2023, meaning FDA has flagged significant safety concerns for outsourcing facilities.

For sport, the WADA Prohibited List bans growth hormone releasing factors under section S2. The German Sport University Cologne’s summary of class S2 lists CJC-1295 among GHRH analogs and ipamorelin among growth hormone secretagogues. Our guide to US peptide law covers the legal categories.

FAQ

What is the main difference between CJC-1295 and ipamorelin?

CJC-1295 is a GHRH analog that acts on the GHRH receptor and, with DAC, lasts days by binding albumin. Ipamorelin is a five-amino-acid ghrelin-receptor agonist with short-lived effects. Both release growth hormone in studies, through separate pituitary receptors.

Has the CJC-1295 and ipamorelin combination been studied in humans?

No. As of October 22, 2026, no published controlled human trial has tested the pair. 👤 The rationale comes from physiology studies showing GHRH and a related peptide, GHRP-2, act together on growth hormone release in men.

What is the difference between CJC-1295 with DAC and without DAC?

CJC-1295 with DAC carries an albumin-binding linker, giving a half-life of roughly 6 to 8 days in human studies. The no-DAC version, often called Mod GRF 1-29, lacks that linker and clears much faster. Published human trials tested the DAC version.

How do GH-releasing peptides differ in mechanism?

GHRH analogs like CJC-1295, sermorelin and tesamorelin act on the GHRH receptor. Secretagogues like ipamorelin and GHRP-6 act on the ghrelin receptor. They differ in selectivity, duration, and effects on other hormones such as cortisol.

Are CJC-1295 and ipamorelin FDA approved?

No. Neither is an FDA-approved drug as of October 22, 2026. CJC-1295 appears on the FDA’s withdrawn-nominations list with serious adverse event notes, and ipamorelin remains in Category 2 for outsourcing facilities. Tesamorelin, a related GHRH analog, is approved for one specific indication. Our peptide comparisons hub and pages on sleep and energy research and muscle and performance research list related compounds.

Closing Note

CJC-1295 and ipamorelin press different buttons on the same gland. Each has a small human record, CJC-1295 in hormone-level studies and ipamorelin in a post-surgery trial, and the popular pairing has never been tested as a pair.