yes i take peptides · shopping companion
IGF-1 LR3
Long Arg3 IGF-1
Category · For EnergyStatus · RUOCitations · 22Cancer Concern
The verdict
No. This is the molecule on this site we'd most strongly recommend against for any healthy adult.
By source — cost, legality, risk
- FDA-approved brandNot availableNone — no FDA approval (Increlex is rhIGF-1, different molecule)No brand exists for IGF-1 LR3.
- Compounded 503ANot availableNot legally compoundedLR3 is not a recognized therapeutic; no 503A pathway.
- RUO research-chemical site$80–$180/moSold for research onlyHighest. Entire off-label channel; purity, identity, endotoxin status unverified.
- Gray-market overseas raw$30–$70/mo at 50mcg/dIllegal to import for human useHighest. Active gray channel; LR3 identity verification is the recurring failure mode (often shipped as plain IGF-1).
Stop signals · abort if
- any episode of severe hypoglycemia (loss of consciousness, seizure, requiring assistance)
- new vision changes (papilledema, retinopathy)
- jaw or facial weakness (Bell's palsy)
- persistent severe headaches
- any new mass or unexplained pain
- new airway-obstruction symptoms (tonsillar hypertrophy)
Sources · top 5 of 22
- 01Lu Z, et al. Recombinant expression of IGF-1 and LR3 IGF-1 fused with xylanase in Pichia pastoris. Applied microbiology and biotechnology. 2023;107(14):4543-4551. PMID: 37261455.
- 02White A, et al. IGF-1 LR3 does not promote growth in late-gestation growth-restricted fetal sheep. American journal of physiology. Endocrinology and metabolism. 2025;328(1):E116-E125. PMID: 39679943.
- 03White A, et al. Attenuated glucose-stimulated insulin secretion during an acute IGF-1 LR3 infusion into fetal sheep does not persist in isolated islets. Journal of developmental origins of health and disease. 2023;14(3):353-361. PMID: 37114757.
- 04Engel MG, et al. Intranasal long R3 insulin-like growth factor-1 treatment promotes amyloid plaque remodeling in cerebral cortex but fails to preserve cognitive function in male 5XFAD mice. Journal of Alzheimer's disease : JAD. 2025;103(1):113-126. PMID: 39610283.
- 05Stremming J, et al. Sheep recombinant IGF-1 promotes organ-specific growth in fetal sheep. Frontiers in physiology. 2022;13:954948. PMID: 36091374.