Growth hormone axis
IGF-1 LR3
Also called Long R3 IGF-1, LR3-IGF-1
IGF-1 LR3 is a lab-modified form of insulin-like growth factor 1, the hormone that carries out many of growth hormone's effects. The changes make it last longer in the body. It was made for cell-culture research and has not been tested as a medicine in people.
Overview
IGF-1 LR3 is a lab-modified form of insulin-like growth factor 1, the hormone that carries out many of growth hormone's effects. The changes make it last longer in the body. It was made for cell-culture research and has not been tested as a medicine in people.
How it works
Proposed: binds the IGF-1 receptor like natural IGF-1, but its modifications reduce binding to IGF-binding proteins, so more of it stays free and active for longer. Expected effects mirror IGF-1 (growth signaling, glucose lowering), but this has not been studied in human trials.
What research shows
Doses studied in people
No published human dosing data; doses circulating online are not based on clinical trials.
Read this first: these are the amounts given to participants in published studies or written on official prescribing labels, reported for reference. They are not recommendations. Trial doses were chosen for specific patients under medical supervision, and a dose that is safe in one person can be harmful in another.
Weekly protocol
How the schedule looks week by week. Each chart says where it comes from: a prescribing label, a clinical trial, or a protocol commonly reported online.
Commonly reported protocol
Commonly reported, not studiedOne week
Once daily, in the morning or after a workout, with food · Subcutaneous injection
Syringe units (U-100)
Dose by week
Supplies for one course (estimate)
Counts only. This site does not sell or link to supplies.
Reference only, not a recommendation. Charts marked "commonly reported" describe what public sources say people use. They have not been tested in trials, and their safety and effect are unknown. Label and trial schedules were set for specific patients under medical supervision. Use the calculator only to understand the arithmetic.
Vial math
Many research vials hold 5 or 10 mg of powder. This table shows how much ends up in each mark on a U-100 insulin syringe for common amounts of added liquid. It is arithmetic only, not a dose.
| Vial | Liquid added | Concentration | Per unit (0.01 mL) | |
|---|---|---|---|---|
| 5 mg | 1 mL | 5 mg/mL | 50 mcg | Open in calculator |
| 5 mg | 2 mL | 2.5 mg/mL | 25 mcg | Open in calculator |
| 5 mg | 3 mL | 1.67 mg/mL | 16.7 mcg | Open in calculator |
| 10 mg | 1 mL | 10 mg/mL | 100 mcg | Open in calculator |
| 10 mg | 2 mL | 5 mg/mL | 50 mcg | Open in calculator |
| 10 mg | 3 mL | 3.33 mg/mL | 33.3 mcg | Open in calculator |
More sizes: all vial sizes · How this works: Syringes and units · Reconstitution guide.
Safety
- No human safety data; risks expected from IGF-1 activity (e.g., low blood sugar) are theoretical for this analogue.
- Unknown long-term safety.
Report side effects of any drug or product to the FDA through MedWatch. For a possible poisoning in the US, call Poison Control at 1-800-222-1222.
Legal status
- FDA
- Not FDA-approved
- Compounding
- Not on FDA's 503A (May 2026) or 503B (March 2025) nomination/category lists; not eligible for compounding
- Sports (WADA)
- Prohibited at all times (S2.3 growth factors: IGF-1 and its analogues)
Rules change often. See Legal status of peptides for how these categories work.
History
Developed as a cell-culture growth supplement. It is not on FDA's compounding nomination lists and has no approved use.
Common questions
Is IGF-1 LR3 FDA-approved?
Has IGF-1 LR3 been tested in people?
No. It was made as a growth supplement for cell-culture research, and its effects have not been studied in human trials.
What doses were studied?
None. There is no published human dosing data, and doses circulating online are not based on clinical trials.
What are the risks?
There is no human safety data. Risks expected from IGF-1 activity, such as low blood sugar, are only theoretical for this version, and long-term safety is unknown.
Is IGF-1 LR3 banned in sport?
Yes. WADA prohibits IGF-1 and its analogues at all times under its growth factors class 1.
Related compounds
Sources
- WADA 2026 Prohibited List (in force 1 January 2026) Regulatory
- FDA: Bulk Drug Substances Nominated for Use in Compounding Under Section 503A (categories list, updated May 14, 2026) Regulatory
- FDA: Bulk Drug Substances Nominated for Use in Compounding Under Section 503B (categories list, updated March 21, 2025) Regulatory
Last reviewed 2026-10-25 · How we research · Found an error? See our corrections policy.