IGF-1 LR3 Dosage Guide: Protocols, Half-Life and Cycle Length
IGF-1 LR3 (Long R3 IGF-1) is an 83-amino-acid analog of insulin-like growth factor 1, modified so it largely evades the binding proteins that normally clear native IGF-1. The result is a much longer half-life and higher potency, which is why dosing is measured in micrograms and given once daily. It is not FDA-approved and is sold as a research chemical. This guide covers the beginner-to-advanced mcg ranges, why the long half-life allows once-daily injection, reconstitution math, cycle length, and the real safety issues. For the background biology, see the IGF-1 LR3 overview.
IGF-1 LR3 Dosage Chart: Quick Reference
The ranges below reflect common research and bodybuilding protocols. Doses are per day, given as a single subcutaneous or intramuscular injection.
| Level | Daily Dose | Frequency | Cycle Length |
|---|---|---|---|
| Beginner | 20–40 mcg | Once daily | 4 weeks |
| Intermediate | 50–80 mcg | Once daily | 4–6 weeks |
| Upper research band | 100–120 mcg | Once daily | 6 weeks max |
Beginner, Intermediate and Advanced Dosing
A reasonable start is 20 to 40 mcg per day for the first week to gauge tolerance, particularly the blood-sugar response. Only after that do intermediate users move into the 50 to 80 mcg range. The upper research band of 100 to 120 mcg per day exists but buys little: beyond roughly 80 mcg the added dose tends to raise the chance of complications more than it adds benefit. Escalating slowly and stopping at the lowest dose that does something is the defensible approach.
Half-Life and Once-Daily Coverage
The whole point of the LR3 modification is duration. Native IGF-1 has a half-life of only 10 to 20 minutes because binding proteins clear it quickly; IGF-1 LR3 resists that binding and lasts roughly 20 to 30 hours. One injection per day therefore holds relatively steady receptor coverage, and splitting into multiple daily doses adds injections without adding much. This is the opposite of short peptides like ipamorelin, where frequent dosing is the norm.
Reconstitution and Dose Math
IGF-1 LR3 comes as a lyophilized powder reconstituted with bacteriostatic water and injected subcutaneously or intramuscularly. A 1 mg vial with 1 mL of bacteriostatic water gives 1000 mcg/mL: on a U-100 insulin syringe, 0.02 mL (2 units) is 20 mcg and 0.04 mL (4 units) is 40 mcg. Using 2 mL of diluent halves the concentration and makes small doses easier to draw accurately. Add the water gently, swirl to dissolve, and refrigerate. Storage handling follows our peptide storage guide, and injection technique is covered in how to inject peptides.
Timing and Injection Sites
With a 20-to-30-hour half-life, exact timing matters less than a consistent once-daily slot. The bodybuilding practice of injecting into a specific trained muscle for localized growth has weak support: a long-acting analog distributes systemically no matter where it goes in, so site selection is mostly about comfort. Post-workout dosing is a convention rather than a pharmacologic requirement.
Cycle Length
Four to six weeks is the standard cycle and matches most of the available research. The limit is receptor desensitization: running longer tends to flatten response rather than extend gains. A break of similar length usually follows before another cycle is considered. This is also why chasing ever-higher doses inside a single long run is counterproductive.
Side Effects and Safety
The concrete acute risk is hypoglycemia. IGF-1 shares insulin-like signaling and can drop blood glucose, so modest doses, eating around the injection, and avoiding empty-stomach dosing are the usual precautions. Because IGF-1 drives broad tissue growth, there are theoretical concerns with heavy or prolonged use about growth of organs and any existing abnormal tissue. Human safety data for this research analog is limited, and none of this is medical advice.
Legal and Anti-Doping Status
IGF-1 and its analogs are prohibited at all times under the World Anti-Doping Agency code, so IGF-1 LR3 is banned in tested sport in and out of competition. It is not an FDA-approved product for muscle building and is sold labeled for research use only, not for human consumption. The figures in this guide describe what protocols report; they are not a recommendation to use a research chemical.
Frequently Asked Questions About IGF-1 LR3
Research and bodybuilding protocols usually start at 20 to 40 mcg per day. Intermediate use runs 50 to 80 mcg daily, and the upper research band is 100 to 120 mcg per day held for no more than about six weeks. Higher doses mostly raise the risk of hypoglycemia and other complications without a matching gain, so the low end is where most people should stay.
Once per day is standard because IGF-1 LR3 has a half-life of roughly 20 to 30 hours, far longer than native IGF-1 at 10 to 20 minutes. That long half-life gives relatively stable receptor coverage from a single daily injection, so splitting into multiple doses is unnecessary. Native IGF-1 needs frequent dosing; the LR3 analog does not.
It ships as a lyophilized powder reconstituted with bacteriostatic water and injected subcutaneously or intramuscularly. A common setup is a 1 mg vial with 1 mL of bacteriostatic water for 1000 mcg/mL, where 0.02 mL (2 units on a U-100 syringe) is 20 mcg and 0.04 mL is 40 mcg. Some users prefer 2 mL of diluent for finer control at low doses. Swirl to dissolve, do not shake, and refrigerate.
Because the half-life is long, precise timing matters less than people assume; a fixed once-daily time is enough for steady coverage. The idea of injecting into a specific worked muscle for local growth is a persistent bodybuilding belief with weak support, since a long-acting analog distributes systemically regardless of site. Post-workout dosing is a convention, not a requirement.
Four to six weeks is the usual cycle, which is also what most of the available research used. That window is chosen to balance effect against receptor desensitization; running longer tends to blunt response rather than extend it. A break afterward, roughly matching the cycle length, is the common approach before considering another run.
The main acute risk is hypoglycemia, because IGF-1 shares insulin-like signaling and can lower blood glucose, which is why doses are kept modest and why dosing on an empty stomach is discouraged. Because IGF-1 drives tissue growth broadly, there are theoretical concerns about growth of organs and existing abnormal tissue with heavy or prolonged use. Human safety data for this research analog is limited.
IGF-1 and its analogs are prohibited at all times under the WADA code, so it is banned in tested sport. It is not an FDA-approved drug for muscle building and is sold as a research chemical, not for human use. Treat the protocol figures here as informational rather than a recommendation.