IGF-1 LR3
Long R3 Insulin-like Growth Factor-1
Also called IGF-1 LR3, Long R3 IGF-1, long arginine 3 IGF-1
Long-acting IGF-1 that bypasses the binding proteins
IGF-1 LR3 is ordinary IGF-1 with two changes that stop it being mopped up by the proteins that normally bind it. That makes it far longer-lasting and considerably more potent than the natural version. It is popular in bodybuilding and it carries the same blood-sugar problem as IGF-1, only for longer.
A modified version of IGF-1, the growth factor that does most of the actual tissue-building work after growth hormone gives the order. The modification stops it being caught by the proteins that normally hold IGF-1 in check, so far more of it stays active for far longer. That is the selling point and the safety problem in the same sentence.
- Half-life
- ~20–30 hours
- Route
- Subcutaneous injection
- Typical dose
- 20–50 mcg/day
- Availability
- Research-only
Studied in people, and well studied in animals
49 papers · 1 clinical trial
What people use IGF-1 LR3 for
Reported uses, roughly in order of how often they are the reason someone goes looking. Whether it works for any of them is a separate question, answered under each one.
- Muscle growth
- The reason it exists in the gym. Because it evades the binding proteins that normally hold IGF-1 in check, more of it stays active and for far longer, roughly a day rather than minutes.
- Recovery between hard sessions
- Used on the theory that it speeds tissue repair. There is no human trial supporting that use; it is extrapolated from what IGF-1 does biologically.
Mechanism of Action
How IGF-1 LR3 works
Growth hormone does not build much tissue itself. It mostly travels to the liver and tells it to make something else: IGF-1, the growth factor that goes out and does the actual work on muscle and other tissue.
So IGF-1 is the messenger at the end of the chain. Taking it directly skips the pituitary, skips the liver, and skips every brake in between.
What LR3 changes
Your body keeps IGF-1 on a tight leash. Around 98% of it circulates bound to carrier proteins, held inactive until it is needed. That binding is a control system, not an inefficiency: free IGF-1 tells cells to grow, and you do not want a permanent grow signal running.
LR3 is IGF-1 with two changes that stop those carrier proteins gripping it properly. The result is a version that stays free and active for hours instead of minutes.
Read that twice, because it cuts both ways. The reason people want it is the reason to be careful with it: you are deliberately removing a brake your body installed on a growth signal.
What that means in practice
The growth instruction is not selective about which cells it reaches. That is why the standing caution around this compound concerns anything already growing that you would rather was not, and why it is one to raise with an actual doctor rather than a forum.
There is also almost no human research on this specific modified version. Most of what people cite is about ordinary IGF-1, which behaves differently precisely because it is still on the leash.
IGF-1 LR3 dosage calculator
Opens at 20 mcg, from the doses reported for IGF-1 LR3. Change any box to match your own vial. It works out where to pull the plunger to.
How much is in the vial?
Printed on the label, in milligrams
How much water did you add?
Bacteriostatic water, in millilitres
What dose are you taking?
The dose you already intend to use
Which syringe?
Barrel size, printed on the wrapper
Draw to
0.4 units
on a 0.5 mL insulin syringe (0.004 mL)
That lands under 2 units, which is very hard to draw accurately by eye. Adding more water spreads the same dose over more of the barrel.
- Strength once mixed
- 5 mg/mL
- Doses in the vial
- 500
10 mg in 2 mL makes 5 mg/mL. A 20 mcg dose is 0.004 mL of that, which is 0.4 units.
Want a rounder number? Adding 50 mL instead would put this dose at exactly 10 units, which is easier to draw accurately.
This is arithmetic, not advice. It converts a dose you already have into a mark on a syringe. It does not tell you what dose to take, and IGF-1 LR3 is not prescribed by us. Dosing belongs with a qualified clinician.
IGF-1 LR3 side effects: what people reported
The same profile as IGF-1, stretched out. That is the important part: the low blood sugar does not pass in twenty minutes, it can hang around for hours.
What most people notice
- Low blood sugar: shakiness, sweating, sudden intense hunger, difficulty concentrating
- Injection-site reactions
- Water retention
- Tiredness a few hours after a dose
Worth keeping an eye on
- Numbness or tingling in the hands from swelling at the wrist
- Joint aching
- Because it lasts far longer than plain IGF-1, one badly timed dose affects a whole afternoon rather than a moment
The ones to take seriously
- Blood sugar can fall far enough to be genuinely dangerous, and it can do so hours after the injection when people have stopped paying attention
- It is a strong growth signal that ignores the body's normal brakes, which is the reason for the cancer caution
Dose matters. Blood sugar effects track the dose closely and are the reason people get into trouble.
Source: Reported use; there is no clinical trial of this modified version in healthy people. This is a summary of published findings, not a complete safety profile and not medical advice. IGF-1 LR3 should only be considered with a qualified clinician who knows your history.
Your Genetics & IGF-1 LR3
The genes involved in how IGF-1 LR3 works
IGF-1 LR3 works through the receptors these genes build, and the genes vary from person to person. Researchers have linked some of that variation to differences in how people respond. A DNA report tells you which versions you carry.
This promoter variant sets your baseline circulating IGF-1. Low-expressers start from a lower IGF-1 set point and may notice a larger relative effect from supplemental IGF-1 LR3.
IGF1R · ••
Variants in the IGF-1 receptor gene change receptor signaling efficiency — the direct target of IGF-1 LR3. Receptor-sensitivity differences shape how strongly the anabolic cascade fires at a given dose.
IGFBP3 · ••
The -202 A/C variant sets IGFBP-3 levels. Although LR3 largely evades IGFBP-3, your binding-protein status still influences the native IGF-1 balance and overall IGF tone alongside the analog.
GHR · ••
The GHR d3 polymorphism governs how efficiently GH is converted to IGF-1 upstream. It shapes your endogenous IGF-1 baseline and how IGF-1 LR3 layers on top of it.
The dots after each gene are where your own result goes. Your report fills them in with the two letters you carry at that position.
Which variants do you carry?
Upload your DNA data, or get tested through our partner, to find out.
Commonly combined with
What IGF-1 LR3 is most often paired with, and why:
CJC-1295
GH/IGF Axis StackModerate EvidenceCJC-1295 (Modified GRF 1-29)
A copy of the brain signal that tells the pituitary to release growth hormone, rewritten so the enzyme that normally destroys it in minutes cannot. Before you read any dose, check which version you have: with DAC it keeps growth hormone up for days, without DAC it produces a short pulse, and nearly every blend sold with ipamorelin contains the second one.
4
Gene variants
30+
Studies
BPC-157
Recovery StackModerate EvidenceBody Protection Compound 157
BPC-157 is the peptide people reach for when something will not heal. Tendons, ligaments, a gut that has been irritated by painkillers, an injury that has stalled. It is a short chain of amino acids copied from part of a protein your stomach already makes, and the animal research on it is unusually consistent for this category: across a lot of separate rat studies, injured tissue healed faster than it did without it. The gap is that this has largely not been repeated in people, and it is not an approved medicine, so nobody is checking what is in the vial you buy.
3
Gene variants
19+
Studies
Follistatin-344
Muscle StackEmerging EvidenceFollistatin-344 (FST-344)
A naturally occurring protein that binds and neutralizes myostatin and activin — the body's built-in limiters on muscle growth. By sequestering myostatin, Follistatin-344 removes a key brake on hypertrophy, which is why it's one of the most discussed (and still early-stage) research peptides for muscle and recovery.
4
Gene variants
20+
Studies
Sourcing & access
Where to buy IGF-1 LR3
IGF-1 LR3 is sold as a research compound, not a licensed medicine, so quality and legal status vary widely by country and vendor. If you're sourcing it, treat independent purity testing as non-negotiable.
- Insist on a recent third-party Certificate of Analysis (COA) for the exact batch — labs like Janoshik verify purity and identity.
- Check the legal status where you live before ordering — it differs from country to country.
- Reconstitute correctly with bacteriostatic water and start at a conservative dose.
IGF-1 LR3
Long-acting IGF-1 that bypasses the binding proteins
$59.96at Swiss Chems
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Educational information only, not medical advice. Some outbound links are affiliate links (disclosed, at no extra cost to you). Most peptides are not FDA-approved — consult a qualified professional and check your local laws before purchasing.
Worth knowing before you consider IGF-1 LR3
Interactions and situations where there is a specific reason to be careful. Where the honest answer is that nobody has studied something, it says so and says what that leaves open.
- Eat with it, and keep eating
- The most practical line here. The blood-sugar drop is longer than with plain IGF-1, so a single meal at injection time is not enough cover.
- It was designed to escape the body's controls
- The binding proteins it evades exist to regulate IGF-1. Removing that regulation is exactly what makes it potent and exactly what makes it less forgiving.
Last updated · literature counts verified against PubMed on
Frequently Asked Questions
What is the difference between IGF-1 LR3 and regular IGF-1?
IGF-1 LR3 is an engineered analog with an extended half-life and a substitution that stops IGF binding proteins from inactivating it. Native IGF-1 lasts only minutes and is mostly bound; LR3 stays free and active for hours, making it far more potent for sustained IGF-1 receptor signaling.
Why does IGF-1 LR3 affect blood sugar?
The IGF-1 receptor shares signaling machinery with the insulin receptor, so activating it can lower blood glucose. This is why IGF-1 LR3 is dosed carefully and often timed around food. Your insulin- and IGF-pathway genetics influence how pronounced the glucose effect is.
Does genetics affect IGF-1 LR3 response?
Yes. IGF1 promoter variants set your baseline IGF-1, IGF1R variants determine receptor sensitivity to the analog, IGFBP3 status shapes the binding-protein balance, and the GHR d3 polymorphism governs upstream GH-to-IGF conversion. A genetic peptide report profiles these for safer, more effective dosing.
Learn more about IGF-1 LR3
Your next move
Two ways forward with IGF-1 LR3.
Not sure it's for you?
How does IGF-1 LR3 relate to your genes?
Your report scores IGF-1 LR3 against your receptor, pharmacogene and pathway variants and shows the genetic markers relevant to it, with commonly cited dosing information to review with a clinician.
Analyze my DNA — $99Already decided?
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