IGF-1 LR3 dosage and evidence
Written by Aaron CuhaReviewed Sep 2026
The short answer
A long-lasting, lab-made form of IGF-1. It has only been studied in animals, for muscle growth and repair.
Evidence grade for IGF-1 LR3: Preliminary. The rule: studied in people, but no published study has had people take it. The sum on this page: 1 human study where nobody was given it. A grade counts how much has been done to people, not whether it works.
- People given it
- 0
- Human studies
- 0
- Found nothing
- 0
Dose
No human dose established
Amounts that circulate in forums and on vendor pages are not a human dose. No published study on this page has given this compound to people and reported a result.
Commonly reported amounts, in mcg. IGF-1 LR3 has no approved label and no human dosing trial.
Amounts commonly reported by people buying IGF-1 LR3, recorded for this archive's reconstitution calculator, are 20, 40, 50 and 100 mcg. They are self-reports rather than trial doses, and this archive does not recommend any of them. No human dose has been established for IGF-1 LR3.
| Reported amount | Where the number comes from |
|---|---|
| 20 mcg | Commonly reported, no published human dosing trial |
| 40 mcg | Commonly reported, no published human dosing trial |
| 50 mcg | Commonly reported, no published human dosing trial |
| 100 mcg | Commonly reported, no published human dosing trial |
8 effects reported, 5 unwanted, 3 wanted, by people using it, not a trial
Goal pages: Fat loss and metabolism, Muscle and strength, Hormones and growth hormone
In plain English
In plain English, from Aaron
This is how I would explain it to a friend. The evidence, with the numbers, is further down the page.
IGF-1 LR3 is a shot that copies IGF-1, the growth signal your liver makes when growth hormone tells it to. It is changed so it stays active for about a day instead of minutes. It goes straight to the growth switch on your cells. It is not approved for anything, and it is banned in sport at all times.
What people take it for
- Building muscle, sometimes in one spot by injecting near that muscle.
- Healing tendons and injuries.
- Getting growth hormone effects without the hormone.
- Keeping muscle into old age.
What studies in people showed
There are no human trials on this page. None. Everything is animals. In rats given a steroid drug that wastes muscle, this version was about 2.5 times stronger than normal IGF-1 at reversing the loss. In pigs, four days of it went the wrong way. They gained less, ate less, and their own growth hormone and IGF-1 fell. In mice, muscle that was gene engineered to make its own IGF-1 stayed strong into old age. That was a gene, not a shot, and it was mice. So the muscle idea rests on mice and rats. The pig study says the body can fight back and shut down its own supply. Nobody has tested any of it in people.
What people report
Reports, not study results
The good
- A pump and fullness in the muscle near the shot.
- Faster recovery, as people report it.
- Better sleep for some.
The bad
- Low blood sugar: shaky, sweaty, dizzy, sometimes within an hour of the shot. People learn to eat first, and it can be dangerous.
- Water retention and a puffy look.
- Headaches and stiff joints.
- Fear about growth of things you do not want to grow. It hits the growth switch on every cell. There is no human data either way.
- Fakes. This is one of the most faked products on the grey market.
Where these come from: No trial data exists in people, so there is no trial table of side effects. Everything above is from user forums, mostly r/PEDs and r/Peptides, and from clinic write-ups.
My bottom line
Zero human trials, a pig study that went backwards, and a real low blood sugar risk. This is a research chemical people inject on faith. I would not put it in my body.
An opinion, not a finding. I am a coach, not a doctor.
What it has been measured to do
What people using it report
Real people telling you what happened to them. Nobody checked it, and the people who post are not a fair sample, so it cannot prove anything works. It is still the best guide on this page to what people actually do with IGF-1 LR3, what they expect, and what goes wrong. The full account, including the negative reports, is below.
Animal and lab work, not yet tested in people
Real results, but from animals or cells, not people. What works in a mouse often does not work the same way in a person. Nobody can patent this, so nobody would ever earn back the cost of a study in people. That is usually why there is none. The record on this one is set out below.
- Growth hormone and IGF-12 animal or lab studies · users report on this
- Feeling less hungry1 animal or lab study
- Keeping or building muscle1 animal or lab study
- Losing weight1 animal or lab study
32 of the 36 indexed goals have no study of any kind behind IGF-1 LR3
No study in people, animals or cells on this page reports a result for these. That does not prove IGF-1 LR3 does nothing for them. It does mean anything you have heard about IGF-1 LR3 and one of these did not come from a study cited here.
Show full evidence
What is IGF-1 LR3?
A long-lasting, lab-made form of IGF-1. It has only been studied in animals, for muscle growth and repair.
IGF-1 LR3 is a changed version of IGF-1, a growth signal your body makes. Two small changes stop it from sticking to the proteins that normally hold IGF-1 in check. That makes it last about a day. There are no human studies on this page. In rats given a steroid that breaks down muscle, it was about 2.5 times stronger than normal IGF-1 at reversing that breakdown. In pigs it went the other way. Four days of it lowered the pigs' weight gain, food intake, growth hormone and their own IGF-1. The idea that it builds muscle rests mostly on mice. Mice built to make extra IGF-1 in their muscles kept bigger muscles into old age. It is not approved. It is banned in sport at all times.
How does IGF-1 LR3 work?
It switches on the IGF-1 receptor. That tells cells to grow, divide and make protein. Because it does not stick to its usual carrier proteins, it keeps working longer.
What have studies in people found about IGF-1 LR3?
There is no evidence in people for IGF-1 LR3. No study, no case series, no test of how the body handles it, and no registered trial. Every published experiment used rats, sheep, pigs, monkeys, cells in a dish, or a lab machine used for drug testing in sport.
- The closest evidence in people is for a different molecule: plain lab-made human IGF-1, sold as mecasermin (Increlex) for children with a severe IGF-1 shortage. A European registry (NCT00903110) followed 306 patients from December 2008 to May 2021. 80 had at least one episode of low blood sugar and 224 had none. That works out to 0.11 episodes, and 0.01 serious episodes, per patient per year of treatment. Children who had gone low before, and those with Laron syndrome, were more likely to. This is natural IGF-1, in children with a shortage, dosed and watched by specialists. It is the best guide there is to what boosting IGF-1 does to a person.
- What has been checked is the product, not its effect in people. In 2010, lab scientists tested a black market injection vial. It held Long-R3-IGF-I with a lab tag still stuck to one end, a handle used to purify proteins in the lab. The authors say nobody has described what this tagged form does in people, and that it was more likely leftover lab material than something made for injection.
- PubMed searches under each of its names find no study where a person was given it, and no trial is registered. It has been sold for three decades without one.
- The newest animal result found nothing. In 2025, 14 growth-restricted sheep fetuses got IGF-1 LR3 at 1.17 micrograms per kg per hour for a week (7 animals) or the carrier liquid alone (7 animals). Body weight, insulin, blood sugar, oxygen and the insulin response to sugar did not differ. Amino acids in the blood fell in the treated animals and not in the others. The authors declared no conflicts.
What this does not tell you: Everything above is either another species or another molecule, and the difference is exactly what IGF-1 LR3 was built for. Its changes make it stick less to the proteins that normally hold IGF-1 in check. That means more free peptide reaching its target, and it lasts tens of hours in the body instead of minutes. How strong that makes it, and how likely it is to drop blood sugar, has never been measured in a person. The mecasermin registry cannot stand in for it, because natural IGF-1 is held in check by those proteins and the LR3 version is built to escape them. There is no human dose, no comparison of ways to take it, no time frame, no data on mixing it with other drugs, and no side effect record. The doses passed around online have no published basis in any species. The animal data that does exist includes a flat result in sheep. It also includes a result in pigs, cited on this page, where four days of drip lowered daily weight gain, food intake and the pigs' own IGF-1.
What do people who took IGF-1 LR3 report?
This is what real people say happened to them, good and bad. Nobody measured it. A report cannot tell a real effect from the lift people get just from expecting it to work, from a diet or training change made at the same time, or from what was really in the vial. We still put it near the top. It is the next best thing to a study in people: what happens when real people use it, including what goes wrong.
- Low blood sugar is the centre of the entire discussion. Board write-ups describe it as by far the most frequent problem, cite clinical figures where a large minority of people receiving IGF-1 experienced it at some level, and treat a small number of severe episodes including seizure as the reason the dose ceiling exists.
- The dose figures that circulate run from roughly 15 mcg daily at the low end to figures around 50 to 60 mcg described as common in performance use, with the strong recurring position being that anything approaching or above 100 mcg becomes impractical to manage. Experienced posters repeatedly describe the common figures as more than most people need.
- The routine described for avoiding a low blood sugar episode is eating carbohydrate and protein around administration, and it is presented as mandatory rather than optional.
- Beyond blood sugar, the claim made on these boards is that outward side effects are few, which is an absence of complaints in a group with every reason not to complain rather than a safety finding.
- Individual experience reports are noticeably thinner here than the volume of guidance would suggest. Most of what circulates is compiled protocol material rather than people describing what happened to them, and that gap is itself the most honest thing to say about this compound's community footprint.
Sources: IGF-1 side effect threads and compound profiles on MESO-Rx and Steroidology, found by site-restricted search and read in September 2026. Nothing above is attributed to any specific post and no post is reproduced.
The state of the research
IGF-1 LR3 was never meant to be a drug. It was built as a lab supply for growing cells: a version of IGF-1 that escapes the proteins in blood serum, so it keeps working in a lab tank. Lab suppliers sell it by the microgram for exactly that. There is no drug programme to have a funding gap, because there was never a company, a disease target or an application. That is the first thing to understand about the empty record. This is not an unpatentable medicine nobody would pay to test. It is a lab tool that ended up in vials.
The disease a company would have chased, muscle wasting, was chased with the parent molecule instead, and that history is not encouraging. Lab-made human IGF-1 is approved only for a narrow childhood shortage. The registry above shows its main problem: low blood sugar, in about a quarter of closely watched patients, and more often in those with the most severe form of the disease. A version built to escape the body's brakes would be expected to make that risk bigger, not smaller, and nobody has checked.
The second fact is the ban. IGF-1 and its cousins are banned in sport at all times. That shuts off the only big market anyone would build a legal business around, and it leaves a supply chain that answers to nobody. The result is on record, not just a theory. When scientists checked a black market vial, it held a tagged, half-finished lab form of the protein. Nobody has studied that form in a person at all, and it was sold as if it were what the label said.
One question here is truly unsettled, not just unstudied: does boosting IGF-1 in an adult raise cancer risk? Studies that follow large groups of people have often linked higher IGF-1 in the blood with several cancers. In cells, there is no doubt IGF-1 makes cells grow and divide. What does not exist is any study that gave healthy adults a shot and checked whether their risk changed. A 2026 review of these compounds describes the concern in exactly those terms: it makes biological sense, and it is not proven. Anyone who presents it as settled, either way, is going past the evidence.
The evidence, in charts
Fig. 1a · how many people
306people, across 1 study in people cited here
| Study | People | Share |
|---|---|---|
| NCT00903110, Journal of Clinical Endocrinology and Metabolism 2023 | 306 | 100% |
The whole total is one study of 306. Counts are the number of people each study on this page says it signed up. That includes studies that only watched people and gave nobody the compound. Studies still signing people up are left out, and only studies cited on this page are counted.
Fig. 1b · evidence mix
1 of 7 sources here is a study in people. The rest are not.
- Study in people · done in people114%
- Animal study · done in animals457%
- Review of studies · sums up other studies229%
Counted from the list of sources on this page. It counts only what we cite, so there may be more studies out there. A review counts once, however many studies it sums up.
Fig. 2 · evidence over time
The studies cover 7 different years, 1992 to 2026, counted from the list of sources on this page.
Fig. 3 · legal status at a glance
US
Not approved
UK
Not approved
AU
Not approved
CA
Not approved
Not approved in any of the four countries shown. This is what the law says, not a verdict on the science. See Legal status below for the full text and any notes.
Fig. 4 · how much does what
Nobody has tested different amounts in people
This chart would show how the effect changes as the amount goes up. For this compound, nobody has measured that in people. So we leave it empty. We will not borrow an animal chart and pretend it works the same in people.
Fig. 5 · what the molecule is
- Kind of compound
- Peptide
- Molecule weight
- 9,111 Da
- Half-life
- About 25 hoursLong, 1 to 7 days
- Chain length
- None on file
No amino acid sequence is on file for IGF-1 LR3, so none is drawn rather than guessed from a name.
The studies we cite
- Study in people2023Frequency and Predictive Factors of Hypoglycemia in Patients Treated With rhIGF-1: Data From the Eu-IGFD Registry.
This is the closest human anchor there is, and it is about a different molecule. 306 children with a severe natural IGF-1 deficiency were tracked on prescription recombinant human IGF-1 between 2008 and 2021. Roughly a quarter had at least one episode of low blood sugar and the rest had none. Serious episodes were rare. Children who had gone low before, and those with Laron syndrome, were the most likely to do it again. This is native IGF-1 in monitored children, not the LR3 version people inject.
The European Increlex Growth Forum surveillance registry (NCT00903110), 306 patients enrolled between December 2008 and May 2021. 80 had at least one hypoglycaemia adverse event and 224 had none, at 0.11 events and 0.01 serious events per patient per treatment year; prior hypoglycaemia and Laron syndrome predicted it. This is unmodified recombinant human IGF-1 in children with severe primary deficiency, not the LR3 analogue, and it is the nearest human anchor for what raising IGF-1 receptor signalling does.
- Review of studies2010Detection of His-tagged Long-R³-IGF-I in a black market product.
Someone tested what is actually in a black market vial, and it was not what the label implies. Lab scientists purified one injection vial and ran it through two kinds of lab tests. It held Long-R3-IGF-I with a lab tag still attached to one end. That tag is a handle used to purify proteins, and it is normally cut off. The authors say nobody has described what the tagged form does in a person. They judge it leftover lab material rather than something made for injection.
An injection vial obtained from the black market was analysed by immunoaffinity purification, high-resolution mass spectrometry and ELISA. It contained Long-R3-IGF-I with a hexahistidine tag on the C-terminus joined by a Leu-Glu linker, a laboratory purification handle normally removed. The authors state the effects of His-tagged Long-R3-IGF-I in humans have not been described and that the material was probably a by-product of biochemical work rather than made for injection.
- Review of studies2026The emerging landscape of performance-enhancing peptides modulating GH-IGF1 axis: bridging the gap between clinical evidence and patient self-administration.
A review places IGF-1 LR3 at the very bottom of the evidence ladder: no human studies at all. It puts the compound alongside PEG-MGF in that tier, then sets it against the dosing protocols circulating online. On cancer, the authors describe the worry as biologically believable but unproven, which is neither a clearance nor a warning. They propose a way for doctors to assess patients who turn up after dosing themselves. The authors declare no commercial relationships.
Places IGF-1 LR3 in the lowest evidence tier of the GH-IGF-1 peptides, those with a complete absence of human studies, alongside PEG-MGF, and contrasts that with the dosing protocols circulating online. Describes the mitogenic concern about these compounds as biologically plausible but unproven, and proposes a clinical assessment algorithm for patients presenting after self-administration. The authors declare no commercial relationships.
- Animal study1992Insulin-like growth factor-I (IGF-I) and especially IGF-I variants are anabolic in dexamethasone-treated rats
In rats. The rats were given a steroid that breaks down muscle. IGF-1 LR3 and a similar version were about 2.5 times stronger than normal IGF-1 at reversing that breakdown.
LR3 IGF-I and des(1-3) IGF-I, analogues that bind poorly to IGF-binding proteins, were about 2.5-fold more potent than native IGF-I at reversing catabolism in dexamethasone-treated rats.
- Animal study1997Long [R3] insulin-like growth factor-I reduces growth, plasma growth hormone, IGF binding protein-3 and endogenous IGF-I concentrations in pigs
In pigs. It went the wrong way. Four days of IGF-1 LR3 lowered the pigs' weight gain, how much they ate, their growth hormone and their own IGF-1.
A cautionary species difference: four days of LR3 IGF-I infusion in pigs decreased daily gain, food intake, plasma GH, IGFBP-3 and endogenous IGF-I.
- Animal study2001Localized Igf-1 transgene expression sustains hypertrophy and regeneration in senescent skeletal muscle
In mice. Mice built to make extra IGF-1 in their muscles kept bigger muscles and kept their ability to repair muscle into old age. This is the main reason people think IGF-1 builds muscle.
Muscle-restricted IGF-1 expression in mice produced persistent hypertrophy and preserved regenerative capacity into old age, the mechanistic basis for IGF-1 muscle research.
- Animal study2025IGF-1 LR3 does not promote growth in late-gestation growth-restricted fetal sheep.
In sheep, it was tested properly, and it did not work. Fourteen growth-restricted sheep fetuses were used: seven got IGF-1 LR3 by drip for a week, and seven got the carrier liquid alone. Body weight, insulin, blood sugar, oxygen and the insulin response to sugar came out the same in both groups. One thing did differ: amino acids in the blood fell in the treated animals and not in the others. This is sheep, not people. The authors reported the flat result plainly and declared no conflicts.
14 growth-restricted fetal sheep, 7 infused with IGF-1 LR3 at 1.17 micrograms per kilogram per hour for one week and 7 given vehicle. Body weight, insulin, glucose, oxygen and glucose-stimulated insulin secretion did not differ. Circulating amino acids, notably branched-chain, fell in the treated group and not in controls. A null result, reported as one, with no conflicts declared.
Where to buy IGF-1 LR3
1 seller lists IGF-1 LR3 in our latest read. They are ranked by trust score, then by archive rating, then by certificate tier, then by the lowest price per milligram. Archive evidence is counted before source-backed. Each path is out of 4, and the two are not added. A higher price does not raise the score. The letter is the certificate chip. 0 of them have a published certificate that names IGF-1 LR3.
Some seller links may pay this site when you buy through them. A payment never changes a seller's tier or rank, and no seller has a say in any page.
| Seller | Trust score | Vial sizes | From, per mg | Certificate for IGF-1 LR3 | Seller link |
|---|---|---|---|---|---|
| Pure Health Peptides | 25 InsufficientSource-backed 1 of 4. Archive evidence 0 of 4.C | 2 mg | $49.5 | None found for IGF-1 LR3 | View |
- LC Lab-confirmed: the issuing laboratory echoed this certificate back
- A Current certificate, independent laboratory named, laboratory not yet checked
- B Certificate published, but no laboratory link, older than a year, or the laboratory did not recognise the published lookup
- C No certificate could be read
Every listing and vial size for IGF-1 LR3 · How the trust score is counted
Sellers named on the price pages are ranked by certificate tier, then price, and any affiliate income is disclosed there. Naming a seller is not a recommendation to buy or use anything.
Common questions
Has IGF-1 LR3 been tested in people?
Not in a completed trial cited here. 1 human study where nobody was given it. A long-lasting, lab-made form of IGF-1. It has only been studied in animals, for muscle growth and repair.
What is the IGF-1 LR3 dosage?
No human dose established. Amounts that circulate in forums and on vendor pages are not a human dose. No published study on this page has given this compound to people and reported a result. Commonly reported amounts, in mcg. IGF-1 LR3 has no approved label and no human dosing trial.
Is IGF-1 LR3 FDA-approved?
Not FDA-approved
Is IGF-1 LR3 allowed in sports?
No. IGF-1 and all its lab-made versions are banned in sport at all times by WADA, the world anti-doping agency.