IGF-1 LR3
IGF-1 LR3 is a laboratory reagent sold to bodybuilders. It has never been tested in humans, is not approved anywhere, and the closest approved drug carries serious warnings. This page covers what it is and why we do not publish a protocol for it.
- Legal lane: research reagent. Not approved anywhere; no compounding route.
- Evidence grade: D
- Human trials: none
- Sport: prohibited at all times
What it is
IGF-1 LR3 is an engineered 83-amino-acid version of insulin-like growth factor 1, altered so that it binds poorly to the proteins that normally keep IGF-1 inactive in the blood. The practical effect is that more of it stays free and active for longer. It was made as a cell-culture reagent, and that is still its only legitimate use.
What the evidence shows
There are no human trials of IGF-1 LR3. None. There is no pharmacokinetic data in people, no dose-finding work, and no safety database.
What exists instead is the label of mecasermin (Increlex), an approved IGF-1 product used in children with severe primary IGF-1 deficiency. It is a different molecule given under close medical supervision, so it is not a guide to using IGF-1 LR3. It does show what this hormone does when given to people:
- Low blood sugar is the signature problem. The label reports hypoglycemia in a large share of treated patients, and seizures from it are documented.
- The label carries a warning about malignant neoplasia. IGF-1 is a growth signal, and the concern about feeding undiagnosed cancers is on the approved label, not a rumor.
- Enlarged tonsils, snoring and sleep apnea, and injection-site reactions are also listed.
- Treatment requires eating before or after each dose, and a doctor monitoring blood sugar.
Why there is no protocol here
We publish dosing when it comes from an FDA label, a published human study, or documented prescriber practice. For IGF-1 LR3 there is none of the three. The numbers circulating in forums were not derived from any study, and the hypoglycemia and cancer warnings on the approved IGF-1 label are the reason we are not going to repeat them.
If you are considering this compound, the honest summary is that nobody, including the people selling it, knows what a safe dose in a healthy adult is.