In Plain English
IGF-1 is the hormone that actually carries out much of what growth hormone signals for. Normally, most of it is bound up by carrier proteins that release it in a controlled way. IGF-1 LR3 was redesigned so those carriers cannot hold it — meaning far more of it stays active, for far longer. Potency and risk here are the same property, not a trade-off between two.
What people use it for. Muscle growth. It has a reputation for being potent, and that reputation is not unfounded.
What to know before you buy. This is the compound in our range that most warrants genuine caution, and it would be dishonest to soften that. It was designed as a laboratory reagent for cell cultures, not as something to put in a person, and it has never been tested in a human trial. The modification that makes it powerful works by removing the control system your body normally uses to keep IGF-1 in check. The realistic acute risk is low blood sugar, which can last longer with this version than it would otherwise. The longer-term concern is that this is a growth signal, and growth signals do not selectively grow only the things you want. If you use it, do so with medical supervision.
What It's Used For
| Goal | What that rests on |
|---|---|
| Muscle growth | IGF-1 is the hormone that carries out much of what growth hormone signals for |
| Extended activity | Engineered to resist the binding proteins that normally clear it quickly |
| Honest caveat | No human trials of this analogue exist. It was designed as a laboratory cell-culture reagent. Medical supervision is strongly advised |
The left column lists goals people commonly pursue with this compound; the right column states what that rests on. These are described uses and research findings, not proven outcomes or treatment claims. Individual results vary and no outcome is promised.
Pricing & Sizes
Ships sealed and lyophilized — stable for years at room temperature, reconstitute before use, or ask and it will be reconstituted free at the volume shown below. Free shipping on every order, no minimum. Third-party COA available for every batch — HPLC purity and mass spec verification.
Reconstitution — bacteriostatic water: 1mg vial at 2mL = 0.5mg/mL, so 10 units on a 100-unit syringe draws 0.05mg. Concentrations are arithmetic from vial content and diluent volume, not a dosing recommendation.
Text To OrderAt a Glance
- Class
- Long R3 insulin-like growth factor 1 — an 83-amino-acid analogue of human IGF-1
- Modification
- An arginine substitution at position 3 plus a 13-residue N-terminal extension, which together sharply reduce binding to IGF binding proteins
- Consequence
- Substantially longer active half-life and greater free-fraction potency than native IGF-1
- Human data
- No controlled human trials of IGF-1 LR3. Research use only; primarily a cell-culture reagent
- Regulatory (US)
- Not FDA-approved for any indication. Not on the July 2026 PCAC agenda
- Format
- 1mg vial
Safety and regulatory status — read first
IGF-1 LR3 was engineered as a laboratory cell-culture reagent, not as a therapeutic. There are no controlled human trials of this analogue. Because the modifications deliberately defeat the body’s own regulatory binding proteins, the normal biological brakes on IGF-1 activity do not apply to it. IGF-1 signalling is also mechanistically linked to cell proliferation, which is why sustained elevation raises theoretical concerns around growth of existing abnormal tissue. It was not on the July 2026 PCAC agenda.
What the Modification Actually Does
Native IGF-1 circulates almost entirely bound to IGF binding proteins, which control how much is free and active at any moment. That is a regulatory system, not an inefficiency. The R3 substitution and N-terminal extension were designed to reduce that binding so the molecule stays active in culture media — useful in a laboratory dish, and a removal of physiological control in a person.
Hypoglycaemia
IGF-1 has meaningful cross-reactivity with the insulin receptor. The most commonly reported acute adverse effect of IGF-1 analogues is hypoglycaemia, and the extended activity of the LR3 form means any such episode can persist longer than with native IGF-1. This is the acute risk that most warrants clinical supervision.
Proliferation
IGF-1 signalling promotes cell growth and inhibits apoptosis. Epidemiological work has associated higher circulating IGF-1 with certain cancer risks. This does not establish that administered IGF-1 LR3 causes cancer, and no study has tested that. It does mean that sustained supraphysiological signalling through a growth pathway is not a neutral intervention.
Evidence Position
There is essentially nothing to report in humans. The compound has no clinical trial programme, no approved indication anywhere, and no established dosing derived from human research. Claims about its effects on muscle growth in people are extrapolated from cell culture and animal work with native or other IGF-1 forms, not demonstrated for this analogue.
The bottom line
The compound in this range with the widest gap between how potent it is and how little is known about using it in people. It was built as a laboratory reagent, it has no human trial data, and the modification that makes it strong is the removal of the body’s own control mechanism. Handle accordingly.
Also in the Range
Compare with the CJC-1295 + Ipamorelin blend, which raises IGF-1 indirectly by prompting your own growth hormone — leaving the body's feedback controls intact, which IGF-1 LR3 deliberately bypasses.