IGF-1 LR3
A long-acting lab version of IGF-1, the hormone growth hormone works through.
Overview
IGF-1 is the hormone the liver makes in response to growth hormone. LR3 is an 83-amino-acid analog built for cell-culture work: one swapped amino acid plus a 13-amino-acid tail make it bind poorly to the proteins that normally hold IGF-1 in check, so it stays active longer. It has never been tested as a medicine in people. Use among bodybuilders is based on theory and anecdote.
How it works
Activates the IGF-1 receptor, which drives cell growth, protein building and glucose uptake. Because it largely escapes IGF-binding proteins, more of it stays free and active than with native IGF-1.
Evidence
1/5
Developed as a cell-culture reagent. No human clinical trials of LR3. Human data exists only for the approved native IGF-1 drug (mecasermin), a different product.
Half-life
Longer than native IGF-1 (often quoted as about 20–30 hours); not well studied in humans
Known as
Long R3 IGF-1, Long Arg3 IGF-1, LR3-IGF-1
Compound facts
- Type
- Synthetic IGF-1 analog
- CAS Number
- 143045-27-6
- Molecular Weight
- 9,117.60 g/mol
- Amino Acids
- 83
- Formula
- C400H625N111O115S9
- Sequence
- MFPAMPLSSL FVNGPRTLCG...
Reported benefits
Muscle cell growth
Strongly drives muscle-cell growth in lab and animal studies.
Muscle size and recovery
Reported by bodybuilders; no controlled human data.
Cell growth in culture
Its original use — a potent growth factor for cultured cells.
“Anecdotal” means reported by users, not shown in controlled trials.
Community-reported regimens
Not recommendations. These are commonly cited ranges, shown so you can see what real-world use looks like.
| Plan | Dose | Frequency | Duration | Route |
|---|---|---|---|---|
| Community Range 20–50 mcg; some go higher, which raises hypoglycemia risk. Eat carbohydrates around the dose. | 40 mcg | Once daily, often post-workout | 4–6 weeks, then a break | Subcutaneous or intramuscular |
Reconstitution calculator
Set up for IGF-1 LR3. Switch peptide or vial size any time.
1Mix
Add 2 mL water for 0.5 mg/mL
2Draw
Draw to 8 units = 0.08 mL = 40 mcg
Drag the plunger to set your dose.
3Inject
Next site
Right belly, upper
Tap a site after you inject to keep a rotation.
Pinch the skin, stay 2 in. from the navel, then into a sharps bin.
- Doses per vial
- 25
- Vial lasts
- 35 days
- Good once mixed
- ~21 days
- Syringe
- 30-unit, 0.3 mL
The vial outlasts its ~21-day shelf life once mixed. A smaller vial wastes less.
Math only: concentration (mg/mL) = vial mg ÷ mL of water; units = dose (mg) ÷ concentration × 100. Always double-check against your own vial label and a clinician. This tool does not recommend a dose.
Reconstitution
Diluent: Bacteriostatic water, or 0.6% acetic acid as some sources suggest for stability. Bacteriostatic water (0.9% benzyl alcohol) — allows multiple draws from one vial.
- Wipe both vial tops with an alcohol swab and let dry.
- Draw the diluent, then inject it slowly down the inside wall of the vial — never straight onto the powder.
- Swirl gently or let it sit; do not shake. Foam can damage peptides.
- Solution should be clear. Cloudy, stringy or discolored = discard.
- Common mix: 1 mg + 2 mL = 0.5 mg/mL (40 mcg = 8 units).
Storage
Powder
Freezer / fridge
Keep sealed vial in the freezer (−20 °C) for long-term storage; fridge (2–8 °C) is fine for a few weeks. Keep dry and out of light.
After mixing
~21 days
Refrigerate at 2–8 °C. Never freeze after mixing. Keep upright, capped, and out of light.
Travel
Keep cool
Short trips at room temperature are generally fine for powder; keep mixed vials cold.
- Small vial, small doses — measure with an insulin syringe and label the concentration on the vial.
Side effects & cautions
Reported side effects
- Low blood sugar (shakiness, sweating, confusion) — the main acute risk
- Water retention and joint aches
- Headache
- Injection-site redness or fat changes
- With the approved IGF-1 drug: enlarged tonsils and raised pressure in the skull have been reported
Cautions
- Hypoglycemia can be serious. Do not use fasted, and be extra careful with diabetes or insulin.
- IGF-1 drives cell growth. High IGF-1 is linked with some cancers in population studies, and growth factors may speed existing tumors — avoid with any cancer history.
- Long-term high IGF-1 could in theory cause acromegaly-like changes.
- Prohibited by WADA.
FDA & international status
Not FDA-approved
LR3 has never been approved. The only FDA-approved IGF-1 drug is mecasermin (Increlex, 2005) for severe primary IGF-1 deficiency in children — a different molecule. LR3 is sold as a research chemical.
Regulations change often — verify with the FDA, EMA, MHRA, Health Canada, TGA and WADA before acting.
Where to buy
| Size | Price | Per mg | Stock | Latest COA |
|---|---|---|---|---|
| 1 mg | $69.99 | $69.99 | In stock | 99.03% pure, lot IGF0002 ILS Labs, tested 2026-07-30 |
Amino Club list prices as of 2026-10-07, before promo codes. Multi-buy: 2+ units 5% off, 3+ units 7.5% off, 10+ units 40% off. Prices change; confirm on the product page. Mixing? Their bacteriostatic water is Amino H2O from $19.99.
IGF-1 LR3 at Amino Club
Check sizes, current price and the certificate of analysis (COA) on the product page. Sold for in-vitro research only.
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- Look for a batch-specific COA with HPLC purity (≥98%) and mass-spec identity.
- Typical vial sizes: 1 mg.
FAQ
Is this the same as Increlex?
No. Increlex is mecasermin, a copy of natural human IGF-1, made and tested as a drug. LR3 is a longer, modified analog made for lab cell culture and never tested as a medicine.
Why do people say to eat before dosing?
IGF-1 pulls glucose into cells much like insulin does. Dosing on an empty stomach raises the chance of a blood-sugar crash.
How do I measure such a small dose?
Mix with more water so each dose is a readable volume. At 0.5 mg/mL, 40 mcg is 8 units on a U-100 insulin syringe.