Verified July 2026 · Cited to primary sources
IGF-1 LR3: Evidence Grade D. Animal studies only, unproven in humans.
A long-acting IGF-1 analogue marketed for muscle growth on the strength of its mechanism alone. There is no published human efficacy trial for it, and it's banned in sport.
The honest verdict
IGF-1 LR3 is not FDA-approved and not legally compoundable; it's research-only. Human evidence is Grade D: there is no published human efficacy trial for the analogue itself, so the muscle-growth claims rest on mechanism, not proof. It is also WADA-prohibited (S2). We don't link gray-market sources.
IGF-1 LR3 at a glance
- Class
- Synthetic long-acting analogue of insulin-like growth factor 1 (IGF-1)
- Mechanism
- A modified, long-acting form of IGF-1 that activates the IGF-1 receptor to drive the PI3K/Akt/mTOR protein-synthesis and satellite-cell pathways. That's the theoretical basis for its muscle-growth marketing.
- Also known as
- Long R3 IGF-1, IGF-1 Long Arg3, LR3-IGF-1
- Research applications
- Muscle growth and body recomposition (marketed; no published human efficacy RCT)
- Research reagent / cell-culture growth supplement (its legitimate laboratory use)
- Forms
- subcutaneous injection
- Legal status
- Research-only
- WADA (anti-doping)
- Prohibited (S2, IGF-1 and its analogues explicitly named) at all times
- Evidence grade
- Grade DAnimal studies only, unproven in humans
How we grade evidence
Every grade comes from a fixed A to F rubric: human-trial strength, not hype or affiliate status. Last verified July 6, 2026.
What is IGF-1 LR3?
Compound class: Synthetic long-acting analogue of insulin-like growth factor 1 (IGF-1)
A modified, long-acting form of IGF-1 that activates the IGF-1 receptor to drive the PI3K/Akt/mTOR protein-synthesis and satellite-cell pathways. That's the theoretical basis for its muscle-growth marketing.
How strong is the evidence for IGF-1 LR3?
Grade D: there is no published human efficacy RCT of IGF-1 LR3 itself (rule 5 fired: animal/mechanistic evidence only, no human efficacy trial). The muscle-growth case rests on IGF-1's known biology and animal/tissue work, not on a controlled human trial of this specific analogue. Human efficacy for IGF-1 LR3 is effectively absent.
Primary sources (3)
Is IGF-1 LR3 legal? (Status July 2026)
No legal supervised US route.
What is IGF-1 LR3 used for?
IGF-1 LR3 is marketed for the goals below. See how it ranks against other peptides in each, by evidence, not hype.
What does IGF-1 LR3 cost, and how do you access it legally?
Typical cost
UNKNOWN
No verified legitimate price. IGF-1 LR3 has no legal supervised route and is sold only as a gray-market research chemical, which we don't quote or link.
No legal supervised access route right now.
IGF-1 LR3 has no compliant US route today. Vials sold "for research use only" are a gray-market fig-leaf, not a legal loophole, so we don't link them. If you pursue IGF-1 LR3, do it with a licensed clinician, and re-check its legal status first.
Telehealth programs do advertise several compounds in this position as prescribable online. We checked those advertised menus against the law in peptide telehealth programs.
Is IGF-1 LR3safe? Side effects & risks
No human efficacy or safety trials for IGF-1 LR3 specifically. Predictable IGF-1-axis risks apply from the drug class: hypoglycemia, edema, and a theoretical cancer-promotion concern from sustained IGF-1 receptor activation. It is sold only as a gray-market research chemical with no legal supervised US route, and it is WADA-prohibited (S2) at all times.
Medical disclaimer: This page is independent editorial information, not medical advice, and Best Peptide For That is not a medical provider. We do not provide dosing. Talk to a licensed clinician before starting, stopping, or changing any peptide or medication. Full medical disclaimer.
Free tool
Peptide reconstitution calculator
Enter the mg in the vial and the ml of bacteriostatic water, and get the concentration plus the units to draw on an insulin syringe. It does the arithmetic on your numbers, and it never suggests a dose. See all four calculators.
FAQ
IGF-1 LR3 FAQ
Does IGF-1 LR3 build muscle?
There is no published human trial showing IGF-1 LR3 builds muscle. The case for it rests on IGF-1's known biology and animal/tissue data, not a controlled human study of this specific analogue, so on our scale it is Grade D, unproven in humans.
Is IGF-1 LR3 legal?
There is no legal supervised US route. IGF-1 LR3 is not FDA-approved and not legally compoundable; it's sold only as a gray-market research chemical. It is also banned in sport: WADA prohibits IGF-1 and all its analogues under S2 at all times.
Is IGF-1 LR3 banned in sport?
Yes. WADA explicitly prohibits IGF-1 and its synthetic analogues (which includes IGF-1 LR3) under S2, growth factors, banned at all times, in and out of competition, regardless of dose or route.
From our portfolio
Tracking IGF-1 LR3?
Titrate is an iOS app for logging doses, schedules and progress over time, with a reconstitution calculator built in. It tracks, it does not prescribe.
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