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Peptide library › Growth hormone axis
IGF-1 LR3
Also known as Long R3 IGF-1
Modified, longer-acting form of insulin-like growth factor 1.
What people use it for
- Muscle growth and recovery (popular use)
- Cell culture research
What IGF-1 LR3 does in the body
IGF-1 is the hormone that carries out many of growth hormone's effects on muscle, bone and other tissues. The LR3 version has an extra 13 amino acids and one substitution, so it binds poorly to IGF-binding proteins and stays active much longer than natural IGF-1.
Strength of evidence
Very limited in humans: developed mainly as a laboratory reagent. (Mecasermin, a natural-sequence IGF-1, is approved for children with severe IGF-1 deficiency.)
Look up the evidence
- Reviews on PubMed: Summaries of the published research
- Clinical trials on PubMed: Published studies in people
- ClinicalTrials.gov: Registered trials, past and ongoing
Live searches of official databases. New to the terms? See the glossary.
Reported side effects & risks
- Low blood sugar (hypoglycemia)
- Joint pain, swelling
- Theoretical risk of promoting tumor growth
- Unknown long-term effects
Who should avoid it or take extra care
- Pregnant or breastfeeding
- Under 18
- Current or past cancer (it may promote cell growth; theoretical)
- Diabetes or a tendency to low blood sugar
- Competitive athletes (prohibited by WADA)
Not a complete list. Check with a doctor or pharmacist about your own health and medicines.
Regulatory status
Not approved. Prohibited in sport by WADA.
How it's taken
Route: Injection (unofficial use)
How long it lasts (half-life): About 20–30 hours
Storage
Unreconstituted (powder) vials are usually kept refrigerated or frozen and away from light. Once mixed with bacteriostatic water, keep refrigerated and do not freeze; follow the supplier's stated beyond-use date.
Mixing guides
How much water to add and what each syringe mark holds, worked out for your own dose:
Keep track of IGF-1 LR3 privately
Fiala is a free app for logging doses, tracking vials and setting reminders. No account, and everything you log stays on your phone.
Open IGF-1 LR3 in Fiala How to installMore in Growth hormone axis
- TesamorelinGHRH analog approved to reduce excess abdominal fat in people with HIV-associated lipodystrophy.
- SermorelinShort GHRH fragment that stimulates natural growth hormone release.
- CJC-1295Long-acting GHRH analog, often paired with ipamorelin in popular protocols.
- IpamorelinSelective growth hormone secretagogue (ghrelin-receptor agonist).
- HexarelinPotent synthetic growth hormone secretagogue related to GHRP-6.
- GHRP-2Synthetic growth hormone–releasing peptide used in Japan as a diagnostic test.
- GHRP-6First-generation growth hormone–releasing hexapeptide known for strong hunger effects.
- IGF-1 DESShortened, fast-acting form of insulin-like growth factor 1 sold as a research chemical.
- MK-677Oral growth hormone secretagogue. It is not a peptide, but is commonly tracked alongside them.