CJC-1295: two molecules under one name, what each does, and what was actually measured

CJC-1295 is one of the most heavily marketed “growth hormone” peptides in the physique and anti-aging world, usually sold alongside ipamorelin and pitched as a cleaner way to raise your own growth hormone. The first thing most write-ups skip is that “CJC-1295” is really two different molecules sold under one name: a long-acting version with a drug affinity complex (DAC), which is the one that was studied in people, and a short-acting version without DAC, which is the one most often stacked and which has no published human studies. This page explains what each one does, what DAC changes, what lifters expect versus what researchers actually measured, the downsides, and what users report, with a primary source for every claim. It is educational only, and nothing here is medical advice. For the wider map of how these compounds fit together, start with our explainer on what peptides are.

What is CJC-1295?

CJC-1295 is a synthetic analog of growth hormone-releasing hormone (GHRH), the natural signal your hypothalamus uses to tell the pituitary gland to release growth hormone. It is a modified copy of the first 29 amino acids of GHRH, the fragment that carries the biological activity, with small structural changes that make it resist the enzymes that would normally break the natural hormone down within minutes. It was developed by the Canadian biotechnology company ConjuChem, and the 2005 laboratory paper that first identified it described it as a tetrasubstituted form of hGRF(1-29) with an added reactive lysine group that binds albumin, and in the endocrine literature the long-acting version is written as CJC-1295 or “DAC:GRF.” Put simply, it is not a molecule your body makes; it is an engineered, longer-lived stand-in for a signal you already produce.

When people search for the “CJC-1295 peptide,” they usually mean one of two products. The long-acting form carries the DAC, a chemical linker that binds the peptide to albumin, the most abundant protein in blood, so it stays in circulation for days rather than minutes. In the pivotal human study, the estimated half-life of CJC-1295 was 5.8 to 8.1 days. The second form drops that linker and is sold as “CJC-1295 without DAC,” also called modified GRF 1-29 or mod GRF 1-29; without the albumin anchor it clears quickly, which is why sellers instruct much more frequent injection. Neither form is growth hormone itself. Both are designed to push the gland that makes it, which is a genuinely different mechanism from injecting synthetic growth hormone directly.

What does CJC-1295 do?

CJC-1295 makes the pituitary release more of its own growth hormone, and that extra growth hormone then raises insulin-like growth factor 1 (IGF-1) from the liver. In healthy adults, a single injection of the DAC form raised mean growth hormone 2- to 10-fold for 6 days or more and IGF-1 1.5- to 3-fold for 9 to 11 days. That hormone rise is what it has been shown to do. Whether it builds muscle, burns fat or speeds recovery has not been tested in any published trial.

The mechanism is the same receptor the body’s own GHRH uses. Because the DAC form lingers in the blood for days, it provides a sustained nudge on that receptor rather than the brief pulse natural GHRH gives. A steady background signal might have been expected to flatten the body’s natural rhythm, but a before-and-after study of healthy men found the opposite: pulsatile secretion of growth hormone persisted during continuous stimulation by CJC-1295. One week after a single injection, the frequency and size of growth-hormone pulses were unchanged, but the baseline between pulses rose sharply: trough growth hormone went up 7.5-fold, mean growth hormone 46%, and IGF-1 45%. In other words, the drug mostly raised the floor, not the peaks. The same authors note that the short half-life of natural GHRH limits its therapeutic use, which is the specific problem CJC-1295 was engineered to solve. For how that compares with other peptides, see our peptide half-life reference.

CJC-1295 with DAC vs without DAC: what DAC changes

DAC changes how long the molecule lasts, and with it, almost everything that has been measured. The DAC form binds albumin and has a half-life of about a week in the blood; the no-DAC form does not, and clears quickly. That matters for evidence as much as for pharmacology, because every published human result for “CJC-1295” comes from the DAC form. A 2026 endocrinology review that graded growth-hormone peptides by evidence concluded that CJC-1295 without DAC “remains essentially uncharacterised in the peer-reviewed human literature”, with no controlled human studies, and placed it in its lowest tier alongside compounds supported only by animal extrapolation and user reports. Claims that the no-DAC form produces a more “natural” growth-hormone pulse are, by that review’s account, extrapolated from related compounds rather than measured.

Here is what the human studies actually recorded, side by side with ipamorelin, the compound most often stacked with CJC-1295. Every cell comes from the cited study; where nothing was measured, the table says so.

Two cautions on reading that table. The ipamorelin figures come from an intravenous infusion in healthy men, not the under-the-skin injections people use, so they describe the molecule’s behavior rather than a typical user’s experience. And none of the three columns contains a body-composition result, which is the outcome the marketing is built on. Our physique site covers the stack in practical terms: what CJC-1295 and ipamorelin are each supposed to do and how CJC-1295 compares with ipamorelin.

What do lifters expect, and what was actually measured?

Lifters expect CJC-1295 to deliver what higher growth hormone is supposed to deliver: more lean muscle, less body fat, faster recovery, deeper sleep, and a general “GH optimization” or anti-aging effect. What was actually measured is narrower. The human studies were endocrine pharmacology trials that recorded growth hormone and IGF-1 levels in blood over days and weeks, not muscle gained, fat lost or injuries healed. The 2026 review lists favorable body-composition shifts only as a “potential” benefit and describes the DAC form’s evidence as phase 1 studies in healthy adults with “no controlled efficacy data”.

“Raises growth hormone in a blood test” and “builds muscle you can see” are different claims, and the gap between them is exactly what the sales copy skips. The physique-focused sites in this network take those claims apart one by one:

• The category and the honest expectations: what GH peptides are marketed for in physique circles and realistic expectations and side effects for GH peptides.
• How the class compares with the alternatives people weigh it against: GH peptides versus anabolic steroids.

What does the evidence actually show?

The evidence for CJC-1295 is a small set of short, early-phase human pharmacology studies of the DAC form, plus one patient trial that was stopped early; there is no published human study of the no-DAC form at all. The pivotal study, published in 2006 in the Journal of Clinical Endocrinology and Metabolism, ran two randomized, placebo-controlled, double-blind, ascending-dose trials in healthy adults aged 21 to 61, lasting 28 and 49 days. It produced the growth-hormone and IGF-1 figures in the table above and reported that IGF-1 stayed above baseline for up to 28 days after repeated dosing. A companion 2006 study established that growth-hormone release stayed pulsatile under that sustained stimulation. Those are real findings, but they are hormone measurements in small numbers of volunteers.

Beyond those studies, the clinical record is thin and cautionary. The one program that carried CJC-1295 into patients was a mid-stage trial in HIV-associated lipodystrophy run by its developer, and it did not finish. In July 2006, aidsmap reported that the Phase II study was halted after the death of a study participant, with the cause of death and its relationship to the study drug under investigation and no causal link established. The compound never advanced further. So the evidence picture is not “proven to work” and it is not “proven dangerous”: the larger, longer trials that could show whether CJC-1295 delivers physique or recovery benefits were never completed. Anyone presenting a two-fold rise in a hormone assay as a body-composition result is skipping the step that matters. Our physique site lays out what to realistically expect from GH peptides given exactly this gap.

What are the downsides of CJC-1295?

The main downsides of CJC-1295 are side effects that follow from raised growth hormone (water retention, joint aches, numbness or tingling, and pressure on blood sugar), an unknown long-term safety record, and real uncertainty about what an unregulated vial contains. Short trials in healthy volunteers reported no serious adverse reactions, but they lasted weeks, not the months of use common in physique circles. For a practical walk-through of what users report and what to watch for, see our physique site’s guide to GH-peptide side effects and realistic expectations.

The short early studies were reassuring on their own terms: the pivotal trial reported no serious adverse reactions and described the compound as safe and relatively well tolerated at the tested doses. But a weeks-long study in monitored volunteers is not a safety record for long-term, self-directed use, and the halted patient trial above is a reminder that the record is not uniformly benign. Across the whole class of growth-hormone peptides, the 2026 review lists the reported adverse effects as endocrine and metabolic disturbances including dysglycaemia, fluid retention, muscle and joint pain, and injection-site reactions.

The deeper concern is mechanistic. CJC-1295 works by raising growth hormone and IGF-1 and keeping them elevated. The condition defined by chronically elevated growth hormone and IGF-1 is acromegaly, and its complications are well characterized. An analysis of its mechanism concluded that the principal mediator of insulin resistance in acromegaly is hypersecretion of growth hormone. Joint pain is the most frequent complaint, affecting roughly 70% of people with acromegaly at diagnosis, and the wider syndrome carries metabolic and cardiovascular consequences. That is why the water retention, tingling and joint aches users report are biologically coherent rather than surprising: they are the mild, near-term edge of the same physiology. Nobody has established a dose that raises growth hormone for physique purposes without drifting toward that territory over time, because the studies that would define one were never done.

Two further unknowns sit on top. The first is immunogenicity, the risk that the body mounts an immune response to the injected peptide; as quoted in a presentation to the FDA’s compounding advisory committee on CJC-1295, the agency’s view was that controlling impurities can reduce that risk but requires sophisticated manufacturing and testing. And because much of the supply is sold as “research use only” powder outside any pharmacy quality system, product identity is itself a question; a Norwegian doping-control laboratory identified CJC-1295 in an unknown pharmaceutical preparation submitted by police and customs authorities and noted that some peptide drugs reach the public before entering or completing clinical trials. Our explainer on what the evidence shows about peptide side effects walks through both layers in more detail.

Why is CJC-1295 stacked with ipamorelin?

CJC-1295 is stacked with ipamorelin because the two push growth-hormone release through different receptors: CJC-1295 through the GHRH receptor and ipamorelin through the ghrelin receptor, which users reason should add up to a bigger release. In fitness practice the stack usually pairs ipamorelin with the no-DAC form, the one with no human data. The 2026 review describes the practice as largely driven by anecdotal rationale, with limited controlled evidence for synergy or meaningful body-composition outcomes in healthy people. The two-receptor logic is plausible; the combined result has not been measured.

What does CJC-1295 cost?

There is no approved CJC-1295 product, so there is no reference price to compare against; what people pay is set by whoever sells it, whether a telehealth provider offering it as a compounded prescription or an online vendor selling it as a research-use powder. Price comparisons are further muddied because the DAC and no-DAC forms are sold under the same name, often as a blend with ipamorelin, so two listings for “CJC-1295” may not be the same molecule. In community posts, cost comes up as one reason people give for their choices: some users favor the DAC form partly for less frequent injections and lower cost, and one user comparing growth-hormone peptides said CJC-1295 wins on cost over tesamorelin but disrupted their sleep. For how prices compare across peptides and GLP-1 medicines, see our 2026 peptide and GLP-1 cost index.

Is CJC-1295 banned in sport?

Yes. The World Anti-Doping Agency classifies CJC-1295 under growth hormone releasing factors, prohibited at all times, because these compounds raise the body’s own growth-hormone output. Any athlete in a tested sport should treat it as prohibited in and out of competition. For the physique angle, our recomp site covers what GH peptides do and do not do for physique.

What are people saying about CJC-1295?

Most CJC-1295 talk online is about stacking and versions, not about results. In 17 posts on X that our community tracker collected between July 13 and 19, 2026, users mostly describe CJC-1295 as a growth-hormone secretagogue they run with ipamorelin rather than alone, and several said they wanted first-hand accounts because most write-ups are either clinical summaries or vendor pages. Four themes came up repeatedly:

• DAC versus no DAC. Posters treat the two as practically different compounds, which matches the pharmacology. Some prefer the DAC version for less frequent injections and lower cost, while others worry that DAC keeps growth hormone elevated around the clock instead of in pulses, which they link to insulin resistance and joint pain. That worry lines up with the acromegaly physiology above, although the 2006 study found pulses were preserved and the rise came mostly from a higher baseline.
• Side effects. Individual users described strong flushing early on that faded, and one said it wrecked their sleep and left them with bloodshot eyes, something they did not get from tesamorelin.
• Comparisons. In one community tier list, CJC-1295 sits alongside ipamorelin and sermorelin, below HGH and tesamorelin. One user said CJC-1295 wins on cost but caused sleep problems that tesamorelin did not.
• Timing. Some posters say they take it on an empty stomach so that insulin does not blunt the growth-hormone pulse. That is individual practice, not a tested protocol.

These are a small number of self-reports from one platform over one week, not evidence of benefit or safety. They are useful mainly as a map of what users care about: convenience, cost and side effects, more than the endocrine data.

How to think about CJC-1295

If you are weighing CJC-1295, separate the two molecules first, then separate the chemistry from the claims. The DAC form is a real, clever piece of chemistry that reliably raised growth hormone and IGF-1 for days in small human studies. The no-DAC form, the one most often stacked, has no published human data at all. The claims that either one reliably builds muscle, strips fat or speeds recovery in healthy adults are untested, because those trials were never done. The side-effect picture follows from the mechanism: sustained growth hormone and IGF-1 bring a known set of risks, from water retention and joint aches to insulin resistance.

If your actual goal is a leaner, stronger, better-recovered body, start with that goal rather than the peptide, ideally with a licensed clinician who can weigh training, nutrition, sleep or an approved medication where one is clinically appropriate. It is also worth seeing how CJC-1295 sits among its neighbors: how it compares with its usual partner ipamorelin, how the class interacts with testosterone therapy, and how a very different peptide, thymosin alpha-1, is studied for immune function. If you are evaluating any source, our sister publication lists what to ask before you buy any peptide.

Status: Not FDA-approved; sold by some telehealth providers as a compounded prescription. What this status means.

Educational information only, not medical advice. Every scientific statement on this page is sourced to the primary references linked above. Updated October 12, 2026.