IGF-1 LR3 Dosage: What's Claimed vs Studied

Key takeaways

• There is no human IGF-1 LR3 dose, because no human has been given IGF-1 LR3 in a published study. Every dosage chart online is a forum or seller claim.
• The figures that circulate are 20 to 40 mcg a day, under the skin or into muscle, often after training, in cycles of 4 to 6 weeks on and the same time off. A 2026 medical review reports them as forum practice with no human data behind them.
• The only labeled IGF-1 dose is for mecasermin, a different molecule: 0.04 to 0.12 mg/kg twice daily in children with severe IGF-1 deficiency, always within 20 minutes of a meal, because 42% of children in its trials had hypoglycemia.
• In animals IGF-1 LR3 was several times more potent than IGF-1 and lowered blood sugar more strongly and for longer, yet it was cleared from the blood faster. The '20 to 30 hour half-life' has never been measured.
• This page has no reconstitution example or units table: no legal IGF-1 LR3 product exists to measure.

The direct answer: there is no studied IGF-1 LR3 dosage for humans. The numbers you will find, usually 20 to 40 mcg a day in 4- to 6-week cycles, come from bodybuilding forums, and a 2026 review of performance peptides found no peer-reviewed human study of IGF-1 LR3 at all (Dominikowski 2026). What exists are animal doses, the label dose of the approved IGF-1 drug mecasermin, and a few adult trials of natural IGF-1. This page sets them side by side. Our IGF-1 LR3 profile covers what it is, its risks and its legal status; if you are weighing an oral product instead, see IGF-1 supplements vs IGF-1 peptides.

Claimed versus studied doses

Reading the table, three things matter.

The forum dose matches nothing studied. It is far below the weight-based IGF-1 doses used in people: 20 to 40 mcg is a fraction of the roughly 1 mg twice daily that the Friedlander dose would mean for a 70 kg adult. That does not make it a small dose of LR3. In rats, LR3 was about six times as potent as IGF-1 for growth because it barely binds IGFBP-3, roughly 1,000-fold less tightly than IGF-1 does (Ballard 1993), and its potency in humans has never been measured.

More was not better in animals. The pigs that received a sustained LR3 infusion grew less, ate less, and their own growth hormone and IGF-1 fell (Dunaiski 1997). Species respond differently, which is exactly why animal doses cannot be scaled into human ones.

The approved drug is dosed around food. Mecasermin, a weaker molecule than LR3 by the animal measures, must be given within 20 minutes of a meal or snack, skipped when a meal is skipped, and never doubled to make up a missed dose; the label recommends glucose checks before meals while the dose is being set (Increlex label).

The half-life claim

Many pages state that IGF-1 LR3 has a half-life of 20 to 30 hours, which is used to justify one injection a day. We found no study that measured it in a human. The animal evidence points the other way: because LR3 does not bind the proteins that hold IGF-1 in circulation, it was removed from rat blood more rapidly than IGF-1, and in pregnant rats, whose binding proteins are low, IGF-1 itself was cleared almost as fast as LR3 (Ballard 1993). After a single injection into muscle in rats, the intact molecule disappeared within about 4 hours (Mongongu 2021).

What does last longer is the effect on blood sugar. In pigs, IGF-1 variants that bind poorly to the binding proteins, LR3 among them, suppressed glucose over a much longer period than IGF-1, with a cumulative glucose-lowering effect over four hours about 4 to 8 times greater (Tomas 1997). A short time in the blood combined with a long effect on glucose is the opposite of what a "long half-life, steady levels" story suggests.

What 'cycles', 'post-workout' and 'site injections' are based on

These are the three features of most IGF-1 LR3 charts, and none has a study behind it.

• Cycles of 4 to 6 weeks. Whatever reason a chart gives, no human study has tested cycling, tolerance or recovery with IGF-1 LR3. The pig data do show the body's own GH and IGF-1 falling during LR3 infusion (Dunaiski 1997), but nobody knows how fast that happens or recovers in people.
• Post-workout timing. Untested in humans. It also places the injection at a time when exercise may already have lowered blood sugar, and the approved drug's label advises against exercising in the hours after a dose while the dose is being set (Increlex label).
• Injecting into the trained muscle. Presented as a way to grow one muscle. Injected into muscle in rats, LR3 entered the bloodstream and was cleared within hours (Mongongu 2021), so whatever it does, it does everywhere, including to glucose.

Why there is no reconstitution example or units table

People searching for IGF-1 LR3 dosage often want the next step: how much bacteriostatic water to add to a 1 mg vial and how many units to draw. We do not give that, for three reasons.

• There is no legal product. IGF-1 LR3 has never been approved, is not in any category of FDA's 503A nominations list, and as an 83-amino-acid protein it is a biological product that FDA places outside 503A and 503B compounding, as our profile and the legal tracker explain.
• The content is unverified. Anti-doping laboratories analyzing black-market IGF-1 analogs found abundant oxidized, lower-quality forms of the peptides (Mongongu 2021). A units calculation assumes the vial holds what the label says.
• The error would be in the wrong direction. A dosing mistake with an IGF-1 analog shows up as hypoglycemia, and the approved drug's label already describes a tenfold accidental overdose in a child that needed intravenous glucose (Increlex label).

Our reconstitution calculator and units guide exist for medications a pharmacy has dispensed with a labeled concentration. For the studied doses of peptides that do have a legal form, see the peptide dosage chart.

If you have already injected it

Know the signs of low blood sugar: shakiness, sweating, a racing heart, hunger, confusion, drowsiness. The approved drug's label advises avoiding driving and exercise for 2 to 3 hours after a dose while a dose is being established, and treats hypoglycemia with oral glucose or food, or intravenous glucose or glucagon if consciousness is lost (Increlex label). Anyone on insulin or a sulfonylurea is at higher risk. Headache with visual changes, snoring that is new, or swelling of the face and hands are reasons to see a clinician and tell them what you took; adults given high doses of IGF-1 developed facial and hand swelling, jaw pain and joint pain (Jabri 1994). Our bodybuilding side-effects guide covers the compounds often injected alongside it, and the muscle-stack guide explains why no stack containing it is legal.

Bottom line

The honest IGF-1 LR3 dosage chart has an empty human row. Above it sit pig and rat doses, a pediatric label dose for a different molecule given with meals because of hypoglycemia, and adult IGF-1 trials that changed nothing measurable in body composition. Below it sit forum numbers that match none of them. If you want the evidence on what IGF-1 LR3 is and why there is no legal version, read the IGF-1 LR3 profile.

Frequently asked questions

+−What is the dosage of IGF-1 LR3?

There is no studied human dosage, because IGF-1 LR3 has never been given to people in a published study. The 20 to 40 mcg a day in 4- to 6-week cycles that circulates online comes from bodybuilding forums. The only labeled IGF-1 dose belongs to a different molecule, mecasermin, which is dosed by body weight in children with severe IGF-1 deficiency and given only with a meal because it lowers blood sugar.

+−How many mcg of IGF-1 LR3 should I take?

We do not recommend any amount, and no evidence could support one. Nobody knows how potent IGF-1 LR3 is in humans, how long it lasts, or how far it lowers blood sugar at a given dose. In animals it was several times more potent than natural IGF-1 per microgram, which means a dose that looks small next to the IGF-1 doses used in people may not be small at all.

+−What is the half-life of IGF-1 LR3?

Unknown in humans. The 20- to 30-hour figure repeated online has no study behind it. In rats, IGF-1 LR3 was cleared from the blood faster than natural IGF-1, because it does not bind the proteins that keep IGF-1 in circulation, and after an injection into muscle the intact molecule was undetectable after about 4 hours. Its glucose-lowering effect in pigs did last longer than IGF-1's, which is a different thing from a long half-life.

+−How do you reconstitute IGF-1 LR3 1mg?

We do not give reconstitution instructions for IGF-1 LR3. No US pharmacy may prepare it and no approved product exists, so a 1 mg vial is a research chemical whose content, purity and sterility nobody has verified. Anti-doping laboratories testing black-market IGF-1 analogs found abundant oxidized, degraded forms. Precise arithmetic about an unverified vial produces a precise number about an unknown amount.

+−Should IGF-1 LR3 be injected into the muscle you trained?

There is no evidence either way in humans. Forum protocols often recommend injecting into the trained muscle after a workout, on the theory of local growth, but no study has tested site-specific injection of IGF-1 LR3 in a person. Injected into muscle in rats, it reached the bloodstream and was cleared within hours, so any effect would be systemic, including on blood sugar.

+−What is the dose of mecasermin (Increlex)?

For children 2 and older with severe primary IGF-1 deficiency, the label starts at 0.04 to 0.08 mg/kg twice daily by injection under the skin, increases by 0.04 mg/kg per dose if tolerated for at least a week, and stops at 0.12 mg/kg twice daily. Each dose must be given within about 20 minutes of a meal or snack and skipped if the child cannot eat. That label dose is for a pediatric indication and does not translate into an adult or bodybuilding dose.

+−Can IGF-1 LR3 cause low blood sugar?

It is the most predictable risk. The approved IGF-1 drug caused hypoglycemia in 42% of treated children in its trials, including seizures in some, and its label tells patients to avoid driving and exercise for 2 to 3 hours after a dose while the dose is being set. In pigs, IGF-1 LR3 and related analogs lowered glucose 2 to 3 times more potently than IGF-1 and for longer. Shakiness, sweating, confusion or drowsiness after an injection needs sugar immediately and medical care if it does not resolve.

+−Are IGF-1 injections legal?

Mecasermin is a legal prescription drug for one pediatric indication. IGF-1 LR3 has no legal form: it has never been approved, it is not in any category of FDA's 503A nominations list, and as an 83-amino-acid protein it is a biological product that FDA places outside compounding. The full analysis is in our IGF-1 LR3 profile.

Sources

1. ReviewDominikowski A et al. The emerging landscape of performance-enhancing peptides modulating GH-IGF1 axis: bridging the gap between clinical evidence and patient self-administration. Front Endocrinol 2026;17:1822475. (2026)
2. LabelDailyMed. Increlex (mecasermin) injection prescribing information (Eton Pharmaceuticals; SPL published May 20, 2026; label revised October 2025): dosage and administration, hypoglycemia warning, clinical trial adverse reactions. Read October 10, 2026. (2026)
3. StudyBallard FJ et al. Effects of interactions between IGFBPs and IGFs on the plasma clearance and in vivo biological activities of IGFs and IGF analogs. Growth Regul 1993;3:40-4. (1993)
4. StudyMongongu C et al. Detection of LongR3-IGF-I, Des(1-3)-IGF-I, and R3-IGF-I using immunopurification and high resolution mass spectrometry for antidoping purposes. Drug Test Anal 2021;13:1256-69. (2021)
5. StudyTomas FM et al. IGF-I variants which bind poorly to IGF-binding proteins show more potent and prolonged hypoglycaemic action than native IGF-I in pigs and marmoset monkeys. J Endocrinol 1997;155:377-86. (1997)
6. StudyDunaiski V et al. Long [R3] insulin-like growth factor-I reduces growth, plasma growth hormone, IGF binding protein-3 and endogenous IGF-I concentrations in pigs. J Endocrinol 1997;155:559-65. (1997)
7. StudyFriedlander AL et al. One year of insulin-like growth factor I treatment does not affect bone density, body composition, or psychological measures in postmenopausal women. J Clin Endocrinol Metab 2001;86:1496-503. (2001)
8. StudyJabri N et al. Adverse effects of recombinant human insulin-like growth factor I in obese insulin-resistant type II diabetic patients. Diabetes 1994;43:369-74. (1994)