CJC-1295 side effects: what the human studies reported

The short answer: in the only published human trials, CJC-1295 most often caused injection site reactions, headache, flushing, and diarrhea, and FDA has flagged serious events including a faster heart rate and a whole body vasodilatory reaction. [3] [4] Those trials were small and short, CJC-1295 has never been approved anywhere, and there is no lawful compounding path for it in the United States.

This post covers what the studies recorded, the side effects expected from raising growth hormone and IGF-1 for long periods, and where CJC-1295 stands legally. It does not give dosing advice.

What is CJC-1295?

CJC-1295 is a lab-made version of growth hormone releasing hormone, altered so that it binds to albumin in the blood and lasts about a week. In healthy adults, one injection raised growth hormone 2 to 10 fold for 6 or more days and IGF-1 1.5 to 3 fold for 9 to 11 days. [1] A second study found that growth hormone kept its natural pulses but that baseline levels between pulses rose about 7.5 fold. [2]

That long action is the selling point, and it is also the reason side effects matter: once it is injected, the exposure cannot be switched off for days.

What side effects did the human studies report?

The human safety data come from two randomized, placebo controlled trials in healthy adults, published in 2006, plus a small single dose study. [1] [2] The published abstract reported no serious adverse reactions. [1] FDA's 2024 review of the full papers, covering 63 healthy adults, lists what did happen: [3]

The authors reported no consistent changes in blood or urine tests, glucose, liver tests, or heart tracings. [3] In the single dose study in young men, FDA notes a dose dependent rise in heart rate and short lived redness and tenderness at the injection site. [3]

Were there serious side effects?

FDA's compounding risk list states that it has identified serious adverse events with CJC-1295, including increased heart rate and a systemic vasodilatory reaction, and that available clinical data are limited. [4]

FDA's briefing document also describes a phase 2 trial in people with HIV lipodystrophy that was terminated after a participant died of a heart attack. The attending physician's most likely explanation was undiagnosed coronary artery disease, and the trial's data were never published. [3] One case cannot show that the drug caused the death. The developer withdrew CJC-1295 from clinical trials after it, and FDA found no published study testing whether it works in patients; the only published human studies were in healthy adults. [3]

Animal studies raised further flags. FDA describes bleeding, inflammation, and tissue death at injection sites in rats and dogs given repeated injections, signs of genetic damage in lab tests, and a possible risk of pituitary overgrowth or tumors with long term use that has never been ruled out. [3]

What side effects come from raising growth hormone and IGF-1?

CJC-1295 works by pushing the body's own growth hormone and IGF-1 higher for days at a time. [1] No CJC-1295 study lasted long enough to measure the effects that sustained growth hormone exposure causes, so the best guide is what happens with growth hormone itself.

The FDA label for somatropin, prescription growth hormone, warns about: [6]

• Fluid retention, including swelling, joint pain, and carpal tunnel syndrome, which it says may occur frequently in adults.
• Impaired glucose tolerance and diabetes, which growth hormone may unmask.
• Tumor growth, with advice to monitor people with existing tumors for progression or recurrence.
• Raised pressure inside the skull, thyroid and adrenal changes, and pancreatitis.

A systematic review of growth hormone in healthy older adults found more swelling, joint pain, carpal tunnel syndrome, and breast tissue growth in men, and a trend toward new diabetes and impaired fasting glucose. [7] Whether CJC-1295 raises IGF-1 enough, for long enough, to reproduce those effects has not been studied, which is itself the problem.

Is CJC-1295 FDA approved or legal to compound?

No. CJC-1295 has never been approved anywhere. FDA placed it on its Category 2 list of substances that may present significant safety risks in 2023, and its current bulks page lists it as a nominated but withdrawn substance, not on the 503A bulks list. [5] In its 2024 review, FDA proposed not adding any form of CJC-1295 to the bulks list, citing poor characterization, safety concerns, no evidence of effectiveness, and the existence of approved treatments for growth hormone deficiency. [3]

With no approved product and no bulks list entry, licensed pharmacies have no lawful basis to compound it. Clinic and "research use only" products therefore come with no FDA oversight of identity, purity, or sterility. The CJC-1295 regulatory tracker logs every status change, and the CJC-1295 cost page explains why there is no lawful price to list.

Is CJC-1295 allowed in sport?

No. The WADA Prohibited List places growth hormone releasing hormone and its analogues, including CJC-1295, in section S2, banned at all times in and out of competition. [8]

How does it compare with other growth hormone peptides?

Tesamorelin acts on the same receptor, is FDA approved for one indication, and has a full label of side effect data from phase 3 trials. Sermorelin is an older, short acting version with small human trials. See tesamorelin vs CJC-1295 and sermorelin vs CJC-1295. CJC-1295 is often sold blended with ipamorelin, a pairing never tested in humans; see CJC-1295 vs ipamorelin and the CJC-1295 and ipamorelin blend page. For the growth hormone question itself, read sermorelin vs HGH.

Talk to a clinician first

If you have used CJC-1295 and notice swelling, a racing heart, chest pain, or signs of high blood sugar, talk to a licensed clinician and bring the product label. If low growth hormone is the real concern, an endocrinologist can test for it; the growth hormone deficiency page lists the approved treatments.