People searching “CJC-1295 side effects” usually want a straight answer: what can go wrong, how often, and how serious. Here is the honest picture up front. The published human safety evidence for CJC-1295 is thin. It rests essentially on one small, short study in healthy adults (Teichman et al., 2006), plus one larger trial that was terminated with no results ever published (ConjuChem, NCT00267527). No serious adverse reactions were reported at the doses tested in that single study, but “no serious effects seen in a few dozen people over a few weeks” is not the same as “safe.” Because CJC-1295 works by driving sustained increases in growth hormone (GH) and IGF-1—sometimes for weeks after a single dose—its most important risks are mechanistic and long-term, and those have never actually been measured in humans.
This page is research-use-only (RUO) reference information, not medical advice. Nothing here is a human-use protocol. For any medical decision, consult a qualified healthcare professional.
Documented side effects
It is important to be explicit about evidence quality, because most “CJC-1295 side effect” lists online blur three very different things: what was actually observed in the one human trial, what is reported for the broader GHRH-analog class, and what is a mechanistic concern that has never been tested for this compound.
What the one human CJC-1295 study found
According to PubMed, the only peer-reviewed clinical study (two randomized, placebo-controlled, double-blind ascending-dose trials over 28 and 49 days in healthy adults aged 21–61) reported dose-dependent GH increases of 2- to 10-fold and IGF-1 increases of 1.5- to 3-fold, with IGF-1 staying elevated for up to 28 days after dosing. The authors reported no serious adverse reactions and described the peptide as “relatively well tolerated” (Teichman et al., 2006, DOI). Crucially, the abstract does not publish an itemized breakdown of minor side effects or their frequencies—so any specific percentage you see quoted elsewhere is not traceable to this study.
No serious adverse reactions at tested doses
Over ≤7 weeks, small healthy sample only
Clinical (CJC-1295, DAC) — Teichman et al., 2006
Sustained IGF-1 elevation for weeks per dose
Expected pharmacodynamic effect; the basis of the long-term concern
Injection-site reactions (e.g. erythema)
Commonly reported for the GHRH-analog class; not itemized for CJC-1295
Clinical, related drug (tesamorelin) — Badran et al., 2026
Arthralgia, myalgia, paraesthesia (joint/muscle pain, tingling)
Reported for the GHRH-analog class
Insulin resistance / higher diabetes risk
Not seen in the short CJC-1295 trial; documented with chronic GH/IGF-1 excess
Mechanistic / observational — Thomas et al., 2021; Clayton et al., 2010
Possible cancer-promotion concern
Never tested for CJC-1295; raised IGF-1 linked to slightly higher risk of some cancers
Mechanistic / epidemiological — Clayton et al., 2010; Zhang et al., 2021
Unknown outcomes from the largest human trial
Phase 2 (n=120, 12 weeks) terminated; no safety data published
Registry — ConjuChem, NCT00267527
Class comparator (a related, approved drug)
The closest FDA-approved molecule in the same class, tesamorelin, is a useful honest signal for what to watch for. A 2026 meta-analysis of five randomized trials reported adverse events including arthralgia, myalgia, paraesthesia, and injection-site reactions such as erythema, without serious side effects or glucose perturbation in that dataset (Badran et al., 2026, DOI). These are a different drug’s data—informative about the class, not proof of CJC-1295’s profile.
Who is at higher risk / contraindications
Because CJC-1295 sustains elevated IGF-1, the people with the most to lose are those in whom extra growth signaling is plausibly harmful:
Anyone with cancer or a cancer history. Raised IGF-1 is associated with a slightly increased risk of some cancers, and chronic GH/IGF-1 excess (as in acromegaly) shows a small excess cancer incidence (Clayton et al., 2010; Zhang et al., 2021).
People with diabetes, prediabetes, or insulin resistance. Higher IGF-1/GH is linked to worse metabolic outcomes, including a higher diabetes hazard in acromegaly (Thomas et al., 2021). Notably, the ConjuChem trial itself excluded people with diabetes and anyone using GH secretagogues (NCT00267527)—the sponsors did not consider those groups suitable for study.
Older adults. In a large UK Biobank analysis, higher IGF-1 shifted from protective in the young to associated with increased disease/death in older individuals (Zhang et al., 2021).
Pregnancy, breastfeeding, and children. No data exist; growth-axis manipulation in these groups is untested.
What we do NOT know
For a research peptide, the gaps are not footnotes—they are the headline. Treat unknown long-term safety as a real risk, not a green light.
No long-term human data. The only published trial ran ≤7 weeks in healthy adults (Teichman et al., 2006). The longest planned study, a 12-week Phase 2, was terminated and never reported results (NCT00267527)—so the largest human safety dataset that was supposed to exist simply does not.
The short-acting “no-DAC” version has essentially no human trial data at all. The published evidence is for CJC-1295 with DAC (drug affinity complex). “Mod GRF 1-29” / CJC-1295 without DAC is widely sold but lacks comparable peer-reviewed human safety studies.
Cancer and cardiometabolic outcomes have never been measured for CJC-1295 in humans. The concern is inferred from GH/IGF-1 biology, not from studies of this compound.
Research-grade material is not pharmaceutical grade. Purity, actual peptide content, dose accuracy, and contamination are not independently guaranteed and add risk on top of the molecule itself.
Dosage & handling reference
For laboratory documentation of vial reconstitution and concentration math, see the CJC-1295 dosage reference and the peptide dosage calculator. These are research documentation tools for handling and record-keeping only—not human-use instructions, and not an endorsement of self-administration. No dosing figure changes the evidence gaps described above.
FAQ
Is CJC-1295 proven safe?
No. One small, short study in healthy adults reported no serious adverse reactions (Teichman et al., 2006), but that is a narrow snapshot, not proof of safety—and the larger, longer trial was halted with no published results (NCT00267527). “Not shown to cause serious harm in a few weeks” is not the same as “safe.”
What is the single most serious concern?
Sustained elevation of GH and especially IGF-1, which CJC-1295 (DAC) can maintain for weeks per dose (Teichman et al., 2006). In the wider literature, chronically high IGF-1 is linked to insulin resistance, worse metabolic outcomes, and a modestly higher risk of some cancers (Clayton et al., 2010; Thomas et al., 2021; Zhang et al., 2021). This has never been tested long-term for CJC-1295 specifically.
Are the DAC and no-DAC forms equally risky?
We can’t say they are equal, and that itself is the point: the DAC form has the only human data, while the no-DAC form has essentially none. Absence of published reports is not evidence of safety.