IGF-1 LR3
Also known as: Long R3 IGF-1
IGF-1 LR3 is a modified, longer-acting analogue of insulin-like growth factor 1 used widely as a cell-culture research reagent. It is not approved for human use in Australia.
- Category
- Growth Factor
- Reported half-life
- Reported to be substantially longer than native IGF-1 (not well established in humans)
- Common forms
- Lyophilised powder for reconstitution, Solution (research reagent)
- Research status
- Not approved for human use in Australia; widely sold and used as a laboratory cell-culture reagent only. No marketed human therapeutic product.
- Last updated
- 21 June 2026
Claimed effects
The following effects are reported or claimed by users and in early research. They are not established medical facts and many are not supported by large human trials.
- Reported to activate IGF-1 receptor signalling more persistently than native IGF-1
- Claimed to have reduced binding to IGF binding proteins, extending activity
- Users report interest in muscle growth and recovery
- Early research indicates anabolic and cell-proliferative effects in vitro
How it is reported to work
IGF-1 LR3 is reported to be IGF-1 modified with an extra 13-amino-acid N-terminal extension and a substitution at position 3, changes that reduce its binding to IGF binding proteins. This is proposed to leave more of the molecule free to activate IGF-1 receptors and to prolong its activity. These properties are characterised mainly in cell-culture and laboratory settings, not in controlled human use.
Background
IGF-1 LR3 (Long R3 IGF-1) is a modified analogue of insulin-like growth factor 1. Its modifications are reported to reduce binding to IGF binding proteins, leaving more free, longer-acting peptide. It is widely used as a cell-culture research reagent, not as a medicine. This page is educational information, not medical advice.
What the research actually shows
IGF-1 LR3 is well characterised in laboratory and cell-culture contexts, where it is reported to drive persistent IGF-1 receptor signalling. Controlled human clinical trials using it as an intervention are essentially absent, so any human benefits and safety remain unproven.
| Evidence type | Status |
|---|---|
| Cell-culture/laboratory research | Present |
| Human trials | Lacking |
| Australian approval | None |
What people use it for (reported)
Online, people report using IGF-1 LR3 in attempts to support muscle growth and recovery. These are anecdotal reports, not validated clinical results. Studies suggest potent IGF-1 signalling, but reported benefits should not be read as established facts.
Things to be aware of
IGF-1 LR3 is not approved for human use in Australia. Prolonged IGF-1 signalling carries theoretical concerns including low blood sugar and cell proliferation, and grey-market product identity and purity cannot be verified by sight.
If you have a health concern, the appropriate step is to talk to a qualified healthcare professional rather than self-experimenting. This article is not an endorsement and does not recommend obtaining or using IGF-1 LR3.
Reported positives & side effects
Compiled from research and community reports. These are reported outcomes, not guarantees or medical advice, individual experiences vary widely.
Reported positives
- Reported to drive more persistent IGF-1 receptor signalling than native IGF-1
- Reported interest in muscle growth, fullness and recovery
- Reported to remain active longer due to reduced binding-protein interaction
- Reported anabolic and cell-proliferative effects in laboratory settings
Common side effects
- Reported hypoglycaemia (low blood sugar) symptoms such as shakiness, sweating and hunger
- Reported injection-site soreness or swelling
- Reported fatigue or lethargy after dosing
- Reported localised muscle fullness or water-retention sensations
Rare / serious side effects
- Reported severe hypoglycaemia that may require urgent carbohydrate intake
- Theoretical concerns around tumour promotion from prolonged cell-proliferative signalling
- Reported organ-growth concerns (including the heart) with chronic high-dose use
- Reported allergic-type reactions to impurities in research-grade product
Reported misuse & overdose risks
What has been reported to happen with overuse, excessive dosing, or long-term misuse of IGF-1 LR3. Listed so you can make an informed decision, not to suggest any use is safe.
- Overuse is reported to raise IGF-1 signalling excessively, with chronic misuse linked in concern to organ enlargement, including cardiac and visceral overgrowth.
- Excessive dosing is reported to trigger dangerous hypoglycaemia, with reports of users needing emergency carbohydrate intake.
- Sustained high doses are reported to raise theoretical cancer-promotion risk because IGF-1 strongly drives cell proliferation.
- Stacking with insulin or GH is reported to compound metabolic and growth strain and amplify hypoglycaemia danger.
Reported results timeline
Roughly how long people report it takes to notice effects. A general guide from reports, not a promise, and not advice. Users report effects within days, with blood-sugar-related sensations often noted soon after dosing and anabolic changes building over several weeks.
First effects
Reported muscle fullness and hypoglycaemia-type sensations within days
Noticeable change
Reported subjective size and recovery changes
Clear results
Reported cumulative anabolic effects over a cycle
Peak effect
Reported plateau of effects over an extended run
Commonly reported dosing & protocol
Reported figures only, NOT a recommendation or dosing advice. These are numbers people report using, compiled for education so you can make an informed decision. We do not advise anyone to take IGF-1 LR3. Many peptides are not approved for human use in Australia. Speak to a qualified healthcare professional.
| Route | Subcutaneous injection |
|---|---|
| Typical reported dose | Reported community figures of roughly 20–60 mcg daily; a strong reported risk of hypoglycaemia is associated with these figures |
| Frequency | Reported as once daily |
| Cycle length | Reported in runs of around 4 weeks at a time |
Reported reconstitution (mg → units)
Illustration only: a 1 mg vial + 1 mL bacteriostatic water = 1 mg/mL. A 40 mcg (0.04 mg) dose is about 0.04 mL = 4 units on a U-100 insulin syringe.
Work out the units for your vial → CalculatorCommonly reported as daily dosing over short blocks of roughly four to six weeks with breaks, framed as anecdotal reporting and not medical advice. Sold as a research reagent and not approved for human use in Australia.
Best used with / commonly stacked with
Combinations people report using together. Reported, not recommended, stacking can increase risks.
Safety notes
IGF-1 LR3 is not approved by the TGA for human use in Australia and is intended as a research reagent. Strong, prolonged IGF-1 signalling carries theoretical risks including hypoglycaemia and effects on cell proliferation, and grey-market product purity cannot be verified by consumers. Anyone considering it should first consult a qualified healthcare professional.