recombinant IGF-1 analog · studied for muscle growth and nitrogen retention in rats, cell culture growth factor; muscle and recovery (user reports)

IGF-1 LR3 dosage

IGF-1 LR3 is an 83 amino acid version of IGF-1 that barely binds the carrier proteins, so it is about three times as potent as IGF-1 in rats and lasts longer. It has never been given to humans in a trial. Users commonly inject 20 to 80 mcg once daily, starting at 20 to 30 mcg, for 4 to 6 weeks on and 3 to 6 weeks off. The main hazard is low blood sugar, which can be severe.

By the Peptide Calculations editors · Updated 2026-10-19

20 mcg to 80 mcgper day

Basis: commonly reported. start at 20 to 30 mcg for 7 to 14 days, then raise by 10 to 20 mcg a week if needed; 100 mcg is reported by some but widely considered the ceiling

How often: once daily
When: morning or right after training, with carbohydrates on board
How long: 4 to 6 weeks on, 3 to 6 weeks off
Route: subcutaneous (abdomen) or intramuscular into the trained muscle, by user report
Storage: lyophilized: fridge or freezer; reconstituted: fridge, commonly used within 2 to 4 weeks (commonly reported); it is less stable than small peptides

Dose ranges by source

Range	Per	Basis	Note
20 mcg to 80 mcg	day	commonly reported	start at 20 to 30 mcg for 7 to 14 days, then raise by 10 to 20 mcg a week if needed; 100 mcg is reported by some but widely considered the ceiling
about 3 times the potency of IGF-1	comparison	animal study (Tomas et al., rats, 1992 and 1996)	infused and injected LR3 outperformed IGF-1 for growth and nitrogen retention; no human dose data exists

Titration schedule

Step up on this schedule; stay a step longer if side effects are rough.

Weeks	Dose
1-2	20 to 30 mcg daily
3-6	40 to 80 mcg daily, raised 10 to 20 mcg per week

IGF-1 LR3 dose to units chart

1 mg vial + 2 mL bacteriostatic water = 0.5 mg/mL (5 mcg per unit on a U-100 insulin syringe). 1 mg + 2 mL = 0.5 mg/mL (500 mcg/mL), so 50 mcg = 0.1 mL = 10 units; 20 mcg = 4 units, 80 mcg = 16 units. Some suppliers ship it for reconstitution in dilute acetic acid; follow the vial's instructions. A 0.1 mg vial with 1 mL gives 100 mcg/mL, so 20 mcg = 20 units.

Dose	mL	Units (U-100)	Doses per vial
20 mcg	0.04	4	50
25 mcg	0.05	5	40
30 mcg	0.06	6	33
50 mcg	0.1	10	20
80 mcg	0.16	16	12
100 mcg	0.2	20	10

Different vial or water? Full 1 mg + 2 mL table or set your own numbers below.

Side effects

hypoglycemia (shakiness, sweating, confusion)
headache
nausea
injection site pain or lumps
joint aches
fatigue
with long use, reports of jaw or organ growth

Before you start. There are no human trials of IGF-1 LR3 at all; the risk picture is borrowed from prescription IGF-1 (mecasermin), where hypoglycemia is common and can cause seizures. Do not use it with diabetes, insulin, or sulfonylureas, and never fasted. IGF-1 signaling drives cell growth, so any cancer history rules it out. It is banned in sport. Not medical advice; start low and talk to a clinician.

IGF-1 LR3 dosage questions

How much IGF-1 LR3 should I take?

There is no human dose; it has never been trialed in people. The commonly reported range is 20 to 80 mcg once daily, starting at 20 to 30 mcg. On a 1 mg vial in 2 mL, 20 mcg is 4 units and 50 mcg is 10 units.

How many units of IGF-1 LR3 is 50 mcg?

With 1 mg reconstituted in 2 mL you have 500 mcg per mL, so 50 mcg is 0.1 mL, which is 10 units. With 1 mg in 1 mL it is 5 units. Vials this small make a 2 mL reconstitution easier to measure.

When should I take IGF-1 LR3?

Users commonly inject it after training or in the morning, always with carbohydrates in the last meal or the next one. Taking it fasted is how people end up hypoglycemic. Keep glucose tabs or juice near the first few doses.

Is IGF-1 LR3 dangerous?

The honest answer is nobody has measured it in humans. Prescription IGF-1 causes low blood sugar in a large share of users, and LR3 is more potent because it is not held by binding proteins. Anyone with diabetes, a cancer history, or on glucose-lowering drugs should not touch it.

Sources

Brands we recommend for IGF-1 LR3. We are independent and have no affiliation with any brand: no affiliate links, no referral codes, no paid placements. These are the suppliers whose testing and certificates hold up when we check them.

Licensed Peptides two accredited labs on every lot, certificates public, card and Apple Pay checkout
Core Peptides long track record, public certificates, wide catalog
Ascension Peptides public third-party testing, clear pricing

This page is an educational summary of published labels, trials and commonly reported use. It is not medical advice and does not replace a clinician.