Modified GRF 1-29
Modified GRF 1-29, tetrasubstituted human growth hormone releasing factor 1-29
Written by Aaron CuhaReviewed Sep 2026
Also known as: Mod GRF 1-29, CJC-1295 without DAC, CJC-1295 no DAC, tetrasubstituted GRF(1-29)
In plain English, from Aaron
This is how I would explain it to a friend. The evidence, with the numbers, is further down the page.
This is a shot that tells your pituitary to release its own growth hormone. It is sold as CJC-1295 without DAC. That name is backwards. The DAC is the part that makes a molecule CJC-1295 in the first place. Take it off and you have a different, much shorter acting drug. The famous human study everyone quotes was run on the version with the DAC.
What people take it for
- Better sleep and deeper recovery.
- Losing fat while holding onto muscle.
- Feeling younger without taking growth hormone itself.
- Healing faster from hard training.
What the trials actually showed
This exact version has never been tested in a human being. Not once. The study on the vendor page is a different drug. In that one, healthy adults got the version with the DAC. Growth hormone rose 2 to 10 times for 6 days or more. IGF-1 rose 1.5 to 3 times for 9 to 11 days. It stayed in the body for about 6 to 8 days. You cannot carry those numbers over, because the part that made it last that long is the part your vial does not have. The plain parent peptide has been given to people. Eleven short children got it every night for 6 months. They grew faster. But their growth hormone pattern over 24 hours did not change, and their IGF-1 did not go up in any real way. There is one more thing worth knowing. When Danish customs seized these powders and tested them, the contents had an extra amino acid stuck on the end. What was in the vials was not what the label said.
What people report
Reports, not trial results
The good
- Deeper sleep in the first two weeks is the most common report.
- People say they get hungry, which they take as a sign it is working.
- Some report better skin and faster recovery between workouts.
- It is usually stacked with ipamorelin because the two hit different switches.
The bad
- Tingling or numb hands, and puffy fingers and ankles from holding water.
- Joint and muscle aches, listed for this whole drug family in a 2026 review.
- Blood sugar can drift up. The same review lists raised prolactin and cortisol too.
- Red, itchy lumps where the needle went in.
- You may not be getting the drug at all. That is the seized powder finding, not a rumour.
Where these come from: The water retention, tingling, blood sugar and hormone effects come from a 2026 review of this drug family in clinic patients. The sleep, hunger and injection site reports come from peptide and bodybuilding forums.
My bottom line
The pharmacology here is real, but you are buying a name that does not match the molecule and quoting a trial of a different drug. If you want growth hormone benefits, sleep, lift and get your blood work looked at first, because that is where most people are actually leaking.
An opinion, not a finding. I am a coach, not a doctor.
Overview
Sold as CJC-1295 without DAC, which is a contradiction: the DAC is what makes a molecule CJC-1295. The human trial everyone quotes, 2 to 10 fold higher growth hormone for 6 days or more with a half-life of 5.8 to 8.1 days, was run on the DAC form. No human trial of the version without the DAC has been located.
Start with the naming, because the naming is the error.
The 2005 paper that created CJC-1295 tested three maleimido derivatives of human growth hormone releasing factor 1-29 designed to bond to the free thiol on cysteine 34 of serum albumin. The winner, named CJC-1295, is described in that paper as a tetrasubstituted form of hGRF 1-29 carrying an added maleimidopropionamide derivative of lysine at the C terminus. The four amino acid substitutions and the albumin-binding maleimide are both part of the definition. The maleimide is the Drug Affinity Complex, the DAC.
So a product sold as CJC-1295 without DAC is the tetrasubstituted peptide with the defining half of the molecule removed. It is a real compound. It is just not CJC-1295, and it does not have CJC-1295's pharmacology, because the whole reason CJC-1295 lasts days is that it latches onto albumin.
What the substitutions do on their own is protect the peptide against dipeptidyl peptidase IV, which chews up native GHRH within minutes. So modified GRF 1-29 is best understood as a sturdier sermorelin: the same 29 amino acid GHRH fragment, harder to degrade, acting on the same pituitary receptor, still pulsatile, still short-acting.
The human record is where it matters. CJC-1295 with DAC has a published randomised placebo-controlled trial in healthy adults. Sermorelin, plain GRF 1-29, has decades of human work and was an approved medicine. The tetrasubstituted peptide without the DAC has neither. It reaches the indexed literature mainly through forensic chemistry: a Danish customs seizure analysed in 2019 found modified GRF 1-29 among the seized doping powders, and the seized material carried an extra glycine on the N terminus, meaning what was in the vials was not even the compound named on them.
Mechanism of action
A growth hormone releasing hormone analogue acting at the GHRH receptor on anterior pituitary somatotrophs to trigger growth hormone release, which raises IGF-1 downstream. The tetrasubstitution of the native GRF 1-29 sequence resists dipeptidyl peptidase IV cleavage, extending the peptide's survival in plasma from minutes to somewhat longer, but it does not confer albumin binding. Release stays pulsatile and dependent on the pituitary's own capacity and on the opposing somatostatin tone, which is the practical difference between a secretagogue and injected growth hormone.
Human evidence
None for this compound. The human evidence in this corner belongs to two neighbours: the DAC-bearing CJC-1295 and the unmodified sermorelin.
- CJC-1295 with DAC, healthy adults, randomised and placebo-controlled: growth hormone up 2 to 10 fold for 6 days or more, IGF-1 up 1.5 to 3 fold for 9 to 11 days, half-life 5.8 to 8.1 days.
- Sermorelin, GRF 1-29 amide, 11 short children over 6 months: growth velocity rose, but the 24 hour growth hormone profile and IGF-1 increments did not change significantly.
- Modified GRF 1-29 without the DAC: no human pharmacokinetic study, no human efficacy study, and no registered trial located.
- The only indexed record naming the compound directly is a 2019 forensic analysis of seized doping powder, which found the material carried an extra N-terminal glycine.
What this does not tell you: You cannot carry the CJC-1295 numbers across. The DAC is the reason that molecule lasts days, so removing it removes the property the trial measured. You also cannot carry the sermorelin record across unchanged, because the four substitutions were added specifically to change how fast the peptide is destroyed. What is left is a plausible pharmacology with no human measurement, in a class where seized product has repeatedly turned out to be a different molecule than the label claims.
Reading the research record
There is a second reason the human data thins out here, and it is commercial rather than scientific. ConjuChem developed CJC-1295 and took it into clinical trials; development did not continue to approval. The non-DAC peptide was never a drug candidate at all. It became a product because bodybuilding suppliers could make a DPP-4 resistant GHRH fragment cheaply and because pairing a GHRH analogue with a ghrelin-receptor secretagogue such as ipamorelin became a standard gray-market protocol. Nobody funded a trial of a peptide nobody could patent or sell as a medicine, so the absence of data here is an economic fact as much as a scientific verdict. That said, an economic explanation for missing evidence is not a substitute for the evidence.
The evidence, charted
Fig. 1 · evidence composition
2of 5 citations (40%) are in people
Counted from the citation list on this page. The Human count is the same number shown in the badge at the top. Both understate any literature larger than the sources we cite.
Fig. 2 · evidence over time
Evidence spans 5 distinct years, 1988 to 2026, counted from the citation list on this page.
Fig. 3 · legal status at a glance
US
Not approved
UK
Not approved
AU
Not approved
CA
Not approved
Not approved in any of the four jurisdictions shown. A jurisdiction's classification is a regulatory fact, not a verdict on the science; see Legal status below for the full text and any notes.
Fig. 4 · dose response
No human dose response curve exists
We draw this figure where the data supports it. For this compound in humans it does not, so the panel stays empty rather than borrowing an animal curve and implying it transfers.
Key studies & citations
- Animal2005
Human growth hormone-releasing factor (hGRF)1-29-albumin bioconjugates activate the GRF receptor on the anterior pituitary in rats: identification of CJC-1295 as a long-lasting GRF analog.
The paper that defines the molecule. Three maleimido hGRF 1-29 derivatives were conjugated to human serum albumin, all resisted dipeptidylpeptidase IV and were active in cultured rat pituitary cells. In male Sprague Dawley rats the best compound gave a 4-fold larger growth hormone area under the curve over 2 hours than plain hGRF 1-29 and was still detectable in plasma beyond 72 hours. CJC-1295 is defined here as the tetrasubstituted hGRF 1-29 with the added maleimidopropionamide lysine at the C terminus, which is why a product without that group is not CJC-1295. Rats, not people.
Endocrinology - Human2006
Prolonged stimulation of growth hormone (GH) and insulin-like growth factor I secretion by CJC-1295, a long-acting analog of GH-releasing hormone, in healthy adults.
Two randomised placebo-controlled double-blind ascending dose trials over 28 and 49 days in healthy subjects aged 21 to 61. A single injection raised mean plasma growth hormone 2 to 10 fold for 6 days or more and IGF-1 1.5 to 3 fold for 9 to 11 days, with an estimated half-life of 5.8 to 8.1 days and IGF-1 still above baseline for up to 28 days after multiple doses. No serious adverse reactions. This is the DAC form. It is the study quoted on vendor pages for the non-DAC product, and it is not a study of that product.
Journal of Clinical Endocrinology and Metabolism - In vitro2019
Glycine-modified growth hormone secretagogues identified in seized doping material.
Powders seized by Danish customs were analysed by high resolution mass spectrometry against reference standards and identified as analogues of GHRP-2, GHRP-6, ipamorelin and modified GRF 1-29. In every case the detected material carried an extra glycine at the N terminus. What was in the vials was a modified version of the compound named on them, which is a product identity problem rather than a pharmacology finding.
Drug Testing and Analysis - Review2026
The emerging landscape of performance-enhancing peptides modulating GH-IGF1 axis: bridging the gap between clinical evidence and patient self-administration.
A narrative review that explicitly separates CJC-1295 with DAC from CJC-1295 without DAC and stratifies the whole class into evidence tiers from regulatory-grade randomised data down to a complete absence of human studies. Reported adverse effects across the class include prolactin and cortisol elevations, appetite change, dysglycaemia, fluid retention, myalgia and arthralgia, and injection site reactions, alongside uncertainty about what is actually in unregulated product.
Frontiers in Endocrinology - Human1988
Subcutaneous treatment with growth hormone-releasing hormone for short stature.
The unmodified parent peptide in people. Eleven short children with normal growth hormone secretion were given GRF 1-29 amide at 5 micrograms per kilogram subcutaneously each evening for 6 months. Growth velocity increased in all of them, but the 24 hour growth hormone secretory profile did not differ before, during or after treatment, pulse frequency and amplitude were unchanged, and the IGF-1 increments were not significantly different at any interval. A useful reminder that a growth effect and a measurable hormone profile change are not the same thing.
Hormone Research
Frequently asked questions
Is mod GRF 1-29 the same as CJC-1295?
No, and the vendor name gets it backwards. The 2005 paper defines CJC-1295 as the tetrasubstituted GRF 1-29 plus the maleimide group that binds albumin. Take the DAC away and you no longer have CJC-1295, you have the tetrasubstituted fragment on its own, with none of the multi-day duration.
How long does it last?
Not measured in humans. Native GRF 1-29 clears in minutes and the four substitutions slow the enzyme that does that, so expect something short and pulsatile rather than the roughly 6 day half-life reported for the DAC version.
Is it the same as sermorelin?
Close relatives. Sermorelin is the unmodified GRF 1-29 amide and was an approved medicine with real human data. Modified GRF 1-29 is the same fragment with four amino acid swaps to resist breakdown. Same receptor, same pulsatile mechanism, different resistance to degradation, and only one of the two has been given to people in published studies.
Why is it usually stacked with ipamorelin?
Because they act on two different receptors. A GHRH analogue works at the GHRH receptor and a ghrelin mimetic such as ipamorelin works at the growth hormone secretagogue receptor, and the combination produces a larger pulse than either alone in the published secretagogue literature. No trial has tested modified GRF 1-29 with ipamorelin specifically.
Is what I am buying actually mod GRF 1-29?
Often not. When Danish customs sent seized growth hormone secretagogue powders for mass spectrometry, the modified GRF 1-29 material carried an extra glycine on the N terminus, and so did the GHRP-2, GHRP-6 and ipamorelin in the same seizure. That is the single most concrete thing known about the retail supply of this compound.
What are the reported side effects?
For the class, a 2026 review lists prolactin and cortisol elevations, appetite changes, dysglycaemia, fluid retention, muscle and joint pain, and injection site reactions. None of that has been characterised for this compound specifically because no human study of it exists.