IGF-1 LR3 (Long R3 IGF-1)
Peptide ·Exploratory record · not publication-reviewed ·Updated July 13, 2026
IGF-1 LR3 is a modified recombinant IGF-1 analog with an N-terminal extension and an arginine substitution that greatly reduces binding to IGF-binding proteins. It is not FDA-approved for any human indication, has essentially no published human efficacy or long-term safety data, and is mainly a laboratory research reagent or black-market performance-enhancing substance. Serious concerns include hypoglycemia, soft-tissue or organ growth signaling, edema, neuropathy, tumor-growth risk, contamination or mislabeling, and WADA-prohibited status.
Exploratory record, not a reviewed medical publication.
See the editorial and medical-review policies for the publication gate.
This safety record covers a controlled, investigational, or otherwise out-of-scope substance. It remains available for reference, but it is not part of NutriStack's public supplement publication set.
What the research says.
A quick, data-only summary. The full evidence, dosing, and sources are below.
IGF-1 LR3 (Long R3 IGF-1) is a peptide most often used for used as a cell culture and animal research reagent, activates igf-1 receptor signaling, no approved human supplement or therapeutic benefit. NutriStack rates the overall evidence as insufficient. A typical adult dose is No FDA-approved human dose; no evidence-based supplement dose exists, commonly taken as not recommended for human use; laboratory research reagent only. This profile indexes 3 sources.
- Used as a cell culture and animal research reagent1
- Activates IGF-1 receptor signaling
- No approved human supplement or therapeutic benefit
- Performance claims are not clinically established
- Hypoglycemia
- Sweating or shakiness
- Dizziness
- Any unsupervised human use
- Active cancer or history of cancer without oncology clearance
The bottom line
Evidence rating insufficient. Most-documented uses: used as a cell culture and animal research reagent, activates igf-1 receptor signaling, no approved human supplement or therapeutic benefit. 3 sources indexed (1998–2025), with 0 interaction records on file.
How it works, mechanistically.
Core mechanism
IGF-1 LR3 activates the IGF-1 receptor and downstream PI3K/Akt/mTOR and MAPK signaling pathways, promoting glucose uptake, protein synthesis, cell survival, and cell proliferation. Reduced IGF-binding protein affinity makes more peptide bioavailable than native IGF-1 in experimental systems, which may increase potency and risk. Unlike FDA-approved mecasermin, IGF-1 LR3 lacks approved indications, dosing, pharmacovigilance, and long-term human safety data.
Dosing & protocol.
Any human injection of research-grade IGF-1 LR3 carries major sterility, identity, dosing, and safety risks.
What it actually costs.
Real-world pricing across three quality tiers. Assumes Research reagent vial.
Research-market pricing is not a dosing recommendation; human use is not approved. Updated 2026-06-04.
Full safety detail.
Side effects
- Hypoglycemia
- Sweating or shakiness
- Dizziness
- Edema
- Headache
- Jaw or soft-tissue discomfort
- Neuropathy symptoms
- Injection-site reaction
- Theoretical tumor-growth acceleration
Contraindications
- Any unsupervised human use
- Active cancer or history of cancer without oncology clearance
- Diabetes or recurrent hypoglycemia
- Pregnancy and breastfeeding
- Children and adolescents outside specialist endocrine care
- Competitive athletes subject to anti-doping rules2
- Use of research-grade or black-market injectable products3,1
Sources, by evidence tier.
Numbered references. Citations throughout the page link here.
Mechanistic & preclinical
1- 1Long [R3] insulin-like growth factor-I reduces growth, plasma growth hormone, IGF binding protein-3 and endogenous IGF-I concentrations in pigsOwens PC et al. · Journal of Endocrinology · 1998
Continuous Long R3 IGF-I infusion altered growth and suppressed endogenous GH/IGF-axis markers in pigs.
Reference material
2- 2The 2026 Prohibited List: International StandardWorld Anti-Doping Agency · World Anti-Doping Agency · 2025
IGF-1 and analogues are prohibited growth factors for athletes.
- 3Detection of His-tagged Long-R3-IGF-I in a black market productThevis M et al. · Drug Testing and Analysis · 2010
Analytical testing identified modified Long-R3-IGF-I in a black-market product, underscoring doping and quality concerns.
Common questions.
Quick answers about IGF-1 LR3 (Long R3 IGF-1), drawn from the data on this page.
What is IGF-1 LR3 (Long R3 IGF-1)?
IGF-1 LR3 is a modified recombinant IGF-1 analog with an N-terminal extension and an arginine substitution that greatly reduces binding to IGF-binding proteins. It is not FDA-approved for any human indication, has essentially no published human efficacy or long-term safety data, and is mainly a laboratory research reagent or black-market performance-enhancing substance. Serious concerns include hypoglycemia, soft-tissue or organ growth signaling, edema, neuropathy, tumor-growth risk, contamination or mislabeling, and WADA-prohibited status.
What is IGF-1 LR3 (Long R3 IGF-1) used for?
Commonly cited benefits of IGF-1 LR3 (Long R3 IGF-1) include: Used as a cell culture and animal research reagent; Activates IGF-1 receptor signaling; No approved human supplement or therapeutic benefit; Performance claims are not clinically established. NutriStack rates the overall evidence as insufficient.
What is a typical dose of IGF-1 LR3 (Long R3 IGF-1)?
A typical adult dose of IGF-1 LR3 (Long R3 IGF-1) is No FDA-approved human dose; no evidence-based supplement dose exists. The commonly recommended form is Not recommended for human use; laboratory research reagent only. These are general ranges, not personalized advice; confirm the right dose with a clinician.
What are the side effects of IGF-1 LR3 (Long R3 IGF-1)?
Reported side effects include hypoglycemia, sweating or shakiness, dizziness, edema, headache, jaw or soft-tissue discomfort. This is educational information; check with a healthcare professional before use.
How strong is the evidence for IGF-1 LR3 (Long R3 IGF-1)?
NutriStack rates this as Insufficient, meaning the body of evidence reviewed in NutriStack's tiering framework. Full tier criteria are at https://nutristackapp.com/methodology/evidence-tiers.
Use this with your stack
IGF-1 LR3 (Long R3 IGF-1) in NutriStack.
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