IGF-1 LR3 + CJC-1295 Blend

Last updated: October 17, 2026No human trials on this combination

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How this combination works

The community premise is that CJC-1295 stimulates endogenous GH secretion, which in turn elevates endogenous IGF-1 production, while IGF-1 LR3 provides direct, exogenous IGF-1R stimulation with prolonged bioavailability due to markedly reduced IGFBP affinity. The proposed rationale is that the two compounds act on the same GH-IGF-1 anabolic axis through distinct but convergent mechanisms — upstream GHRH-receptor stimulation driving endogenous IGF-1 production (CJC-1295) and direct IGF-1R agonism that bypasses IGFBP sequestration (IGF-1 LR3) — with the intent to amplify downstream myoblast proliferation and muscle growth signalling. In rodent models, CJC-1295 has been shown to activate IGF-1 signalling and satellite cell repair pathways, and IGF-1 LR3 infusion increased skeletal muscle myoblast proliferation in fetal sheep. These animal findings support mechanistic plausibility for each compound individually but do not test the combination and do not establish additivity. Because both compounds converge on IGF-1R signalling through different upstream mechanisms, combining them produces compounded GH/IGF-1 axis stimulation of unknown magnitude and safety. No study in either component file tests the two compounds together, and the community rationale rests on mechanistic inference only.

Combined mechanism

CJC-1295 is a synthetic GHRH analogue whose maleimidopropionic acid (DAC) modification enables covalent binding to serum albumin (Cys34), extending plasma half-life to approximately 5.8–8.1 days. Acting as a long-lasting GHRH receptor agonist at anterior pituitary somatotrophs, CJC-1295 produces dose-dependent GH secretion and downstream endogenous IGF-1 production. In two randomised placebo-controlled human trials, a single subcutaneous injection produced 2- to 10-fold increases in mean plasma GH for ≥6 days and 1.5- to 3-fold increases in IGF-1 for 9–11 days; multiple doses maintained IGF-1 above baseline for up to 28 days. GH pulsatility is preserved while trough GH levels are markedly elevated, driving the observed IGF-1 increases. In rodent models, CJC-1295 has been shown to activate IGF-1 signalling and satellite cell repair pathways. IGF-1 LR3 is a synthetic analogue of IGF-1 carrying an arginine substitution at position 3 and a 13-amino-acid N-terminal extension. This modification confers markedly reduced affinity for IGFBPs compared with native IGF-1, while retaining high affinity for IGF-1R. Because IGFBPs normally sequester IGF-1 and limit its bioavailability, LR3's low IGFBP affinity results in greater free-ligand availability and prolonged receptor signalling. IGF-1R activation engages ERK and PI3K downstream pathways and, in animal models, stimulates myoblast proliferation, skeletal muscle and organ growth, and cardiomyocyte proliferation. LR3 does not bind IGFBP-3 or IGFBP-4, distinguishing its pharmacology from native IGF-1. When used together, CJC-1295 drives endogenous IGF-1 production via GH-axis stimulation while IGF-1 LR3 provides direct IGF-1R agonism that bypasses IGFBP regulation — two upstream inputs converging on shared IGF-1R signalling. The resulting magnitude of combined GH/IGF-1 axis activation, and whether it is additive, synergistic, or subject to negative feedback limiting responses, has not been studied in any animal or human experiment. No combination pharmacokinetic or pharmacodynamic data exist.

What each component does

IGF-1 LR3View full peptide page →CJC-1295View full peptide page →

Evidence base for this combination

No combo-specific RCTNo study testing IGF-1 LR3 and CJC-1295 together is cited in either compound's approved file (reviewed 2026-10-17). No animal combination study, human pharmacokinetic data, or randomised controlled trial for this pair has been identified. The rationale for combining them is mechanistic inference from each compound studied individually, not evidence that the combination produces additive benefit or is safe.

Safety considerations for this combination

No combination-specific safety data exist for IGF-1 LR3 + CJC-1295. The two compounds have not been tested together in any animal study or human trial. Signals below are from each compound studied individually. Component approved files; no combination study identified
IGF-1 LR3 caused attenuation of glucose-stimulated insulin secretion (intrinsic pancreatic islet defect) following 1-week infusion in fetal sheep, with lower plasma insulin and glucose concentrations. Inherited from IGF-1 LR3 (PMID: 33938236)
IGF-1 LR3 was associated with accelerated tumour growth in a C26 tumour-bearing mouse cachexia model and increased tumour growth in mammary adenocarcinoma-bearing rats, despite limiting muscle wasting in both models. Inherited from IGF-1 LR3 (PMID: 31285507, 8053901)
Class-level adverse effects reported for GH-IGF-1 axis peptides in self-administration contexts — including IGF-1 LR3 and CJC-1295 — include endocrine and metabolic disturbances (prolactin and cortisol elevations, appetite changes, dysglycaemia), fluid retention syndromes, musculoskeletal symptoms (myalgia/arthralgia), and injection-site reactions. PMID: 42395176
Emerging data on GH secretagogues and related peptides highlight potential class-level risks of cardiovascular strain, insulin resistance, dyslipidaemia, and psychiatric instability; these are described as class concerns and not specifically quantified for CJC-1295 alone. Inherited from CJC-1295 (PMID: 41880199)
Both compounds are frequently sourced through unregulated gray-market channels. Products from such channels may be mislabelled, contaminated, or of inaccurate dose. An illicitly manufactured preparation containing CJC-1295 was identified by law enforcement, and widespread mislabelling of gray-market peptides has been documented. Inherited from CJC-1295 (PMID: 21204297, 42395176); Inherited from IGF-1 LR3 (PMID: 42395176)
Significant long-term safety data gaps exist for both compounds individually. Non-approved peptides including CJC-1295 and related IGF-1 axis compounds lack long-term safety data and systematic clinical validation; no combination long-term safety data exist at all. Inherited from CJC-1295 (PMID: 42021992, 41476424)

Contraindications

CJC-1295 is prohibited by WADA under the Prohibited List Section S2 as a GHRH analogue; competitive athletes are contraindicated from its use absent a therapeutic use exemption. IGF-1 LR3 is classified among unregulated peptides lacking regulatory approval for any indication, and its WADA status is not explicitly stated in the reviewed literature. Competitive athletes should verify their sport organisation's current anti-doping rules before use of either compound. Inherited from CJC-1295 (PMID: 41138283, 34665524); Inherited from IGF-1 LR3 (PMID: 42395176)
Neither IGF-1 LR3 nor CJC-1295 is approved by the FDA or any other regulatory authority for human use. Both are marketed as unregulated research compounds. The combination has not been evaluated in any human clinical trial. The absence of established combination contraindications reflects a lack of clinical evaluation, not established safety. Inherited from IGF-1 LR3 (PMID: 42395176); Inherited from CJC-1295 (PMID: 41966639)
Both compounds converge on the GH-IGF-1 axis through distinct upstream mechanisms — CJC-1295 by stimulating endogenous GH and downstream IGF-1 production and IGF-1 LR3 by directly activating IGF-1R with reduced IGFBP buffering. Co-administration may produce compounded GH/IGF-1 axis stimulation of unpredictable magnitude, including potential dysregulation of somatotrophic negative feedback. This is mechanistic inference; no combination study exists. Inherited from CJC-1295 (PMID: 16352683, 17018654); Inherited from IGF-1 LR3 (PMID: 10198302, 42395176); mechanistic inference — no combination study
IGF-1 LR3 attenuated glucose-stimulated insulin secretion in fetal sheep, producing an intrinsic islet defect with lower plasma insulin and glucose concentrations. CJC-1295 and GH-axis peptides as a class carry reported risks of dysglycaemia and appetite changes. Combined glycaemic effects of the two compounds have not been studied. Individuals with diabetes mellitus or predisposition to dysglycaemia may face amplified risk from the combination. Inherited from IGF-1 LR3 (PMID: 33938236); Inherited from CJC-1295/class (PMID: 42395176)
IGF-1 LR3 was associated with accelerated tumour growth in animal cancer models. CJC-1295 further elevates GH-driven endogenous IGF-1, a known growth factor implicated in tumour biology. Combining two compounds that amplify GH-IGF-1 axis activity carries a theoretical compounded mitogenic and neoplastic risk. Use in individuals with active malignancy or relevant cancer history has not been studied; this concern is mechanistic inference only. Inherited from IGF-1 LR3 (PMID: 31285507, 8053901); mechanistic extrapolation to combination — no combination cancer risk data