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CJC-1295 for Muscle Growth: Two Human Trials, No Muscle Measured

Find Peptide Clinics Editorial Desk

CJC-1295 for muscle growth has no trial behind it. A PubMed search filtered to clinical trials returns two studies of this peptide, both published in 2006, and both measured hormones in blood. Neither trial measured muscle size, muscle strength or body composition. The closest controlled test of the underlying idea ran the other way: when researchers gave growth hormone to 16 young men who lifted weights for 12 weeks, the men gained no more muscle than the men on placebo.

The sales pitch rests on a chain of swaps. CJC-1295 raises growth hormone. Growth hormone is anabolic. A peptide that raises growth hormone should build muscle. Each link in that chain has a published answer, and the answers do not line up with the vials on clinic menus. We read the two trials, the FDA’s own 2024 evaluation of the molecule, and the current label of the one approved drug in this chemical family. None of those documents describes muscle gain from CJC-1295.

CJC-1295 for Muscle Growth: What the Two Trials Measured

The first trial is Teichman and colleagues in the Journal of Clinical Endocrinology and Metabolism, March 2006, volume 91, pages 799 to 805, published online December 13, 2005. It bundled two randomized, placebo-controlled, double-blind, ascending-dose studies running 28 and 49 days in healthy subjects aged 21 to 61. Participants received CJC-1295 or placebo under the skin, in one of four ascending single doses in the first study and in two or three weekly or biweekly doses in the second.

The main outcome measures were peak concentrations and the area under the curve for growth hormone and IGF-I. In plain words, the researchers drew blood and measured hormone exposure. After a single injection, mean plasma growth hormone rose two- to ten-fold for six days or more, and mean IGF-I rose 1.5- to three-fold for nine to eleven days. The estimated half-life ran 5.8 to 8.1 days. After multiple doses, mean IGF-I stayed above baseline for up to 28 days. The authors reported no serious adverse reactions and described the drug as relatively well tolerated at the trial doses of 30 or 60 micrograms per kilogram.

Nothing in that list of outcomes is a muscle measurement. No participant’s lean mass was weighed on a scan, and no one-rep max or quadriceps biopsy appears in the paper.

The second trial is Ionescu and Frohman, same journal, December 2006, volume 91, pages 4792 to 4797, published online October 3, 2006. The researchers drew blood at 20-minute intervals across a 12-hour overnight window in healthy men aged 20 to 40, before and one week after a single injection of 60 or 90 micrograms per kilogram. That design answers a question about pulse rhythm. It includes no measurement of muscle.

We ran the PubMed clinical-trial filter on October 31, 2026, and it returned those two records and no others. Neither trial reported a body composition endpoint.

Growth Hormone Itself Lost This Test in 1992

If CJC-1295 works for muscle, the mechanism has to run through growth hormone. That mechanism has a direct trial, and it is older than the peptide.

Yarasheski and colleagues published in the American Journal of Physiology in March 1992, volume 262, pages E261 to E267. Sixteen men aged 21 to 34 were assigned at random to resistance training plus growth hormone (seven men) or resistance training plus placebo (nine men). For 12 weeks both groups trained all major muscle groups in identical fashion while receiving 40 micrograms of recombinant human growth hormone per kilogram per day, or a placebo.

Fat-free mass and total body water rose in both groups, and rose more in the growth hormone group. Whole-body protein synthesis rose more in that group as well. Then the measures that matter to a lifter did not move. Quadriceps muscle protein synthesis, torso and limb circumferences, and muscle strength failed to increase more in the men taking growth hormone.

The authors drew the conclusion themselves: resistance exercise with or without growth hormone produced similar increases in muscle size, strength and muscle protein synthesis. The larger fat-free mass in the growth hormone group, they wrote, came “probably from an increase in lean tissue other than skeletal muscle.” Water and connective tissue can raise a fat-free mass reading without adding contractile fiber.

The claim for CJC-1295 for muscle growth depends on the idea that raising growth hormone builds muscle. A randomized trial tested that idea in young men doing the training that builds muscle, and the extra hormone added lean tissue without adding strength or muscle size.

A Higher IGF-I Number Did Not Track With Growth

The second 2006 trial carries a finding that matters here, because the marketing treats IGF-I as the muscle signal.

In the Ionescu study, trough growth hormone rose 7.5-fold and mean growth hormone rose 46 percent. IGF-I rose 45 percent. The frequency and the magnitude of growth hormone pulses did not change. The authors attributed most of the IGF-I rise to the higher trough level between pulses.

The rise in IGF-I did not correlate with any measured parameter of growth hormone secretion. More hormone in the blood did not predict more growth factor in a clean, dose-controlled way. A clinic that treats an IGF-I number as proof of muscle growth is going beyond what the authors reported.

The One Approved GHRH Analog Is Approved for Fat

Tesamorelin is the closest thing to an approved version of this idea. It is a growth hormone-releasing factor analog, the same class as CJC-1295, and it has a full FDA-reviewed label.

That label, published in DailyMed on July 31, 2026, says EGRIFTA SV is indicated “for the reduction of excess abdominal fat in HIV-infected adult patients with lipodystrophy.” The limitations of use section addresses the questions a buyer would ask. Long-term cardiovascular safety has not been established. The drug “is not indicated for weight loss management as it has a weight neutral effect.”

The safety record of that approved analog covers 740 HIV-infected patients with lipodystrophy in clinical trials, 543 of them in the initial 26-week placebo-controlled phase. The most commonly reported adverse reactions, above 5 percent, were arthralgia, injection site erythema, injection site pruritus, pain in extremity, peripheral edema and myalgia. Section 5.2 tells prescribers to monitor IGF-I and consider discontinuing in patients with persistent elevations, and adds that “the effects of prolonged elevations in IGF-1 levels are unknown.”

A muscle claim appears nowhere on that label. The approved GHRH analog is indicated for excess abdominal fat in HIV-infected adults with lipodystrophy, the label describes a weight neutral effect, and its common side effects include joint pain and muscle pain.

What FDA Wrote About CJC-1295 in 2024

FDA evaluated five CJC-1295-related bulk drug substances at the Pharmacy Compounding Advisory Committee meeting on December 4, 2024. The agency’s briefing document, dated November 15, 2024, states the use it examined: growth hormone deficiency. It also states that “none of the substances are a component of an FDA-approved drug,” and that “we believe the evaluation criteria weigh against placing” the substances on the list that can be used for compounding under section 503A.

The nominations for those substances had been withdrawn, and FDA evaluated them on its own initiative. Muscle growth, athletic performance and body composition do not appear among the uses the agency assessed.

FDA keeps a separate page listing bulk drug substances that may present significant safety risks. CJC-1295 sits there, in the table of substances whose nominations were withdrawn, under language current as of April 22, 2026: “FDA has identified serious adverse events associated with CJC-1295 including increased heart rate and systemic vasodilatory reaction. Available clinical data are limited.”

We covered that record in our article on the FDA adverse event reports for CJC-1295, published October 24, 2026. The federal file names a racing heart and a widening of blood vessels, and describes the clinical data as limited.

What to Ask a Clinic Selling CJC-1295 for Muscle Growth

These are the questions to ask before you pay.

  • Ask which trial supports the muscle claim, and get the citation. If the answer is a paper measuring hormones, that trial does not support the claim.
  • Ask whether the vial is compounded under section 503A or 503B, and by which pharmacy. Ask for the pharmacy’s name in writing.
  • Ask which condition the prescriber is treating. The use FDA evaluated is growth hormone deficiency in a patient with a diagnosed deficiency, not a fitness goal.
  • Ask who monitors IGF-I during treatment and how often, since the approved analog in this class carries a monitoring requirement.
  • Ask for one total monthly cost in writing, including the consultation, the vial, the shipping and any lab work.

Our clinic directory lists clinics by city, and each listing carries a flag saying no license has been checked. Verify each license in the state board lookup before you book, and read the compound reference pages for the substances that do have human data behind them. Sermorelin, a shorter-acting relative of this class, is covered in our sermorelin compound page and in what its old label said about side effects.

Doses differ by prescriber and by product, so we publish no dosing instructions. The trial doses above are study parameters, and the person who can talk to you about your own numbers is a licensed prescriber with your history in front of them.

Frequently asked questions

Does CJC-1295 build muscle?

No controlled human trial has shown that it does. The two published trials of CJC-1295 measured growth hormone and IGF-I in blood and did not measure muscle size, strength or body composition.

Did any CJC-1295 trial measure muscle?

Neither of the two trials in PubMed’s clinical-trial filter did. Teichman 2006 measured hormone concentrations and area under the curve, and Ionescu 2006 measured growth hormone pulses over a 12-hour overnight window.

Why would a peptide that raises growth hormone not add muscle?

Because growth hormone itself failed the direct test. In the 1992 Yarasheski trial, 16 young men trained for 12 weeks and those taking growth hormone gained no more muscle size or strength than the placebo group. The extra fat-free mass came from lean tissue other than skeletal muscle.

Is CJC-1295 approved by the FDA?

No. FDA’s 2024 briefing document states that none of the CJC-1295-related substances are a component of an FDA-approved drug, and the agency concluded that the evaluation criteria weigh against placing them on the 503A compounding list.

Is CJC-1295 with DAC the same substance as CJC-1295 without DAC?

FDA treats them as different active moieties that are not interchangeable. The agency evaluated five related substances separately at the December 4, 2024 committee meeting.

Does tesamorelin build muscle?

Its label makes no such claim. Tesamorelin is indicated for excess abdominal fat in HIV-infected adults with lipodystrophy, the label describes a weight neutral effect, and its common adverse reactions include arthralgia and myalgia.

Sources:

This article is general information for people comparing peptide clinics. It is not medical advice, it is not a recommendation for or against any product, and it carries no dosing guidance. Compounded preparations are not FDA-approved drugs, and the vials sold online are not the products studied in the trials above. Talk with a licensed prescriber about your own history before starting, stopping or changing anything.