Other
IGF-1 LR3
A modified insulin-like growth factor 1: an arginine substitution at position 3 plus a 13-residue N-terminal extension sharply reduce binding to the IGF binding proteins, so more of the peptide stays free and active…
Also known as Long R3 IGF-1 · LR3 IGF-1 · Long R3 IGF-I
ANIMAL DATA ONLY
The evidence is animal and cell-culture work. There are no controlled human dosing trials, so every number below is convention rather than a result.
Recombinant IGF-1 is an approved medicine; this analogue is not, and has no controlled human dosing trials or reliable human pharmacokinetics behind it.
At a glance
Dose summary
No reliable human half-life has been published for IGF-1 LR3, so none is listed rather than guessed at.
No regulator and no trial set these numbers. They describe what people actually do, recorded so you can see the range rather than guess at it — which is not the same thing as a recommendation.
Reconstitution
What to draw, at the usual vial
A 1 mg vial reconstituted with 2 mL of bacteriostatic water gives 0.50 mg/mL. A typical 40 mcg dose is 0.080 mL — pull the plunger to 8 units on a U-100 syringe.
Same dose, other vial sizes
| Vial | Water | Concentration | Draw | Units | Doses |
|---|---|---|---|---|---|
| 1 mg | 2 mL | 0.50 mg/mL | 0.080 mL | 8 units | 25 |
The highlighted row is the one quoted above: the smallest listed vial that holds at least four typical doses. Change any of it — a different vial, more or less water, a different dose — on the reconstitution calculator, which draws the syringe to true U-100 graduations.
Mechanism & evidence
What it is, and what is known
A modified insulin-like growth factor 1: an arginine substitution at position 3 plus a 13-residue N-terminal extension sharply reduce binding to the IGF binding proteins, so more of the peptide stays free and active than native IGF-1 would. It is a growth factor that acts directly on the IGF-1 receptor, NOT a growth hormone secretagogue — it does not ask the pituitary for anything, it bypasses that axis entirely. That distinction is why it sits under "other" rather than with ipamorelin or GHRP-2, and it is also why the risk profile is different: secretagogues are self-limited by pituitary feedback, this is not.
Its legitimate life is as a cell-culture supplement and a research reagent; recombinant IGF-1 itself (mecasermin) is an approved medicine for severe primary IGF-1 deficiency, but the LR3 analogue is not approved for anything in humans and has no controlled human dosing trials behind it. Everything below is bodybuilding practice, not clinical evidence, and no reliable human pharmacokinetics exist for this analogue, which is why no half-life is listed.
Dosing is genuinely in the tens of micrograms — roughly 20-100 mcg per day, not milligrams — which is why vials are sold at 1 mg rather than the 10 mg typical elsewhere on this site: a single 1 mg vial is many weeks of use. Reconstitute and measure carefully, because a decimal error here is an insulin-shock-scale mistake rather than a wasted dose.
Tolerability
Reported side effects
- Hypoglycaemia — the dominant risk. IGF-1 acts on the insulin receptor as well as its own, so shakiness, sweating, palpitations, confusion or fainting can follow a dose, especially fasted, after alcohol, around cardio, or alongside insulin. Anyone using it should eat carbohydrate around the dose and keep fast sugar within reach; severe hypoglycaemia is a medical emergency
- Drives IGF-1 signaling directly and continuously rather than in pulses, which is why an active or suspected malignancy is a hard stop rather than boilerplate
- Localised swelling, numbness or aching at and around the injection site
- Jaw ache, headache and general water retention
- Nerve compression symptoms such as carpal tunnel tingling
- Theoretical risk of growth in tissues you did not intend to grow, including organs, with prolonged use
Hard stops
Do not use this if
- Pregnancy, possible pregnancy, or breastfeeding
- Active, suspected or recently treated malignancy
- Under 18
These are flags, not a screening. They do not replace a conversation with a clinician who knows your history.
Handling
Storage
Keep it cold, keep it dark, and label the vial with the date you mixed it. Discard anything cloudy or past the window above.
Combinations
Commonly stacked with
Stacking multiplies the side-effect surface and makes it impossible to tell which compound did what. Add one thing at a time.
References
Sources
Educational information only, not medical advice. Talk to a licensed clinician before starting, changing, or stopping anything.