Muscle & recovery
IGF-1 LR3, simplified.
Also called Long R3 IGF-1
Early researchA modified, longer-lasting version of IGF-1, the growth factor that growth hormone tells the liver to make. Built for lab cell culture, not people.
- Size
- 83 amino acids
- How it is taken
- Injection
- Status
- Research compound
- Available sizes
- Vials: 1 mg
What is it?
Growth hormone does much of its work through IGF-1. The LR3 version was changed so it does not get locked up by the body’s binding proteins, which makes it much stronger and longer-lasting. It is mainly sold for cell culture work.
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What studies show
- In the labStrongly drives cell growth in lab cultures, which is what it was made for.
- In peopleRegular IGF-1 (mecasermin) is an approved drug for children with a rare growth disorder. LR3 itself has not been studied in people.
What we don’t know yet
- Effects and safety of LR3 in people. There are no human trials.
Side effects and cautions
- Can cause low blood sugar.
- Growth signals like IGF-1 are linked to cancer growth, so this is a real concern with long-term use.
- Banned in sport by WADA.
Is it legal?
Not FDA-approved for human use.
Dosage & schedule evidence
How to read published schedules
Third-party protocols are not established clinical dosing standards. Safe human dose, frequency, and duration may be unknown. Research findings may not translate to safe or effective personal use.
| Measurement | Meaning |
|---|---|
| 1 mg | 1,000 mcg (mass) |
| 100 U-100 units | 1 mL (volume, not dose) |
See third-party published protocols ↗ for research context. North Star does not validate these schedules.
Consult your doctor before considering any peptide for personal use. Educational only, not administration guidance.
Common questions
What is IGF-1 LR3?
A modified, longer-lasting version of IGF-1, the growth factor that growth hormone tells the liver to make. Built for lab cell culture, not people. Growth hormone does much of its work through IGF-1. The LR3 version was changed so it does not get locked up by the body’s binding proteins, which makes it much stronger and longer-lasting. It is mainly sold for cell culture work.
What does the research say about IGF-1 LR3?
Strongly drives cell growth in lab cultures, which is what it was made for. Regular IGF-1 (mecasermin) is an approved drug for children with a rare growth disorder. LR3 itself has not been studied in people.
Is IGF-1 LR3 FDA approved?
Not FDA-approved for human use.
What are the side effects of IGF-1 LR3?
Can cause low blood sugar. Growth signals like IGF-1 are linked to cancer growth, so this is a real concern with long-term use. Banned in sport by WADA.
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This page explains published research in plain language. It is not medical advice, a diagnosis, or a recommendation to take anything, and it does not give dosing. Most peptides here are not FDA-approved, and products sold online vary widely in purity. Rules around peptides are changing, so check the current status and talk with a licensed clinician before starting anything. Last reviewed 2026-10-19.