IGF-1 LR3
IGF-1 LR3 is a synthetic, longer-acting analog of insulin-like growth factor 1 (IGF-1).
We have not published an audit on IGF-1 LR3. Everything below is reference material, not our own reading of the literature, treat it as a starting point for questions, not as a grade.
How it is thought to work
IGF-1 LR3 is engineered to carry growth signals from the liver to muscle, bone, and other tissues for a much longer period of time without being captured by proteins that limit IGF-1 activity. Structural changes in the peptide reduce its affinity for IGF binding proteins and extend its half-life to roughly 20-30 hours. [Source: Peptide Dosing Protocols]
IGF-1 LR3 is a modified version of a natural growth-signaling hormone that lasts much longer in the body because it avoids the proteins that normally deactivate it, allowing it to promote muscle and tissue growth for an extended period. It also lowers blood sugar, which is its main acute safety risk.
Reported side effects
The most common and serious side effect is low blood sugar (hypoglycemia), which occurred in 42% of patients in the closest available human dataset, with rarer but serious risks including enlarged tonsils, increased pressure in the skull, organ growth, fluid retention, joint discomfort, and injection site reactions.
Who should avoid it
People with cancer or a strong cancer history, diabetes or blood sugar problems, pregnancy or breastfeeding, heart or organ disease, those taking insulin, adolescents with open growth plates, and competitive athletes in drug-tested sports should all avoid IGF-1 LR3.
What gets monitored
Monitor glucose levels during titration and keep fast-acting carbohydrates available. [Source: Peptide Dosing Protocols]
What sources report
These are figures published elsewhere, reproduced with their source. Peppersite does not recommend an amount for IGF-1 LR3 or for anything else, and nothing below has been checked against the study it came from.
| Amount | Frequency | Route | Reported by |
|---|---|---|---|
| Standard: 40 mcg/day · Low: 20 mcg/day · High: 100 mcg/day | Once daily4 weeks · 4 weeks on, 4 weeks off | Subcutaneous (SubQ) or intramuscular (IM) injection | Peptide Dosing ProtocolsWhat it saysHide(secondary reference; provider confirmation required). Half-life: 20-30 hours. Standard dosing is 40 mcg/day. |
- Once daily4 weeks · 4 weeks on, 4 weeks off
- Subcutaneous (SubQ) or intramuscular (IM) injection
- Peptide Dosing Protocols
What it saysHide
Common questions
What is IGF-1 LR3?
IGF-1 LR3 is a synthetic, longer-acting analog of human insulin-like growth factor 1.
What is the half-life of IGF-1 LR3?
Approximately 20-30 hours.
What dose ranges appear in IGF-1 LR3 research protocols?
Research-community sources cluster between 20 and 100 mcg per day.
How is IGF-1 LR3 reconstituted?
Add bacteriostatic water to the lyophilized vial and swirl gently.
Open the reconstitution calculator →What is the standard cycle length?
Most protocols cap on-time at 4-6 weeks with at least equal time off.
How real is the hypoglycemia risk?
Very real; hypoglycemia was reported in 42% of subjects.
Should IGF-1 LR3 be injected SubQ or IM?
Both routes are used, with SubQ being the most-cited default.
Can IGF-1 LR3 be combined with insulin?
No, the combination produces additive hypoglycemia.
Sources
- 01Tomas FM, Lemmey AB, Read LC, Ballard FJ. Superior potency of infused IGF-I analogues which bind poorly to IGF-binding proteins is maintained when administered by injection. Journal of Endocrinology (1996)
- 02Tomas FM, Knowles SE, Owens PC, Chandler CS, Francis GL, Read LC, Ballard FJ. Insulin-like growth factor-I (IGF-I) and especially IGF-I variants are anabolic in dexamethasone-treated rats. Biochemical Journal (1992)
- 03Mohan S, Baylink DJ. IGF-binding proteins are multifunctional and act via IGF-dependent and -independent mechanisms. Journal of Endocrinology (2002)
- 04von der Thusen JH, Borensztajn KS, Moimas S, et al. IGF-1 has plaque-stabilizing effects in atherosclerosis by altering vascular smooth muscle cell phenotype. American Journal of Pathology (2011)
- 05Ipsen Biopharmaceuticals. INCRELEX (mecasermin) injection — Highlights of Prescribing Information (2025 revision). FDA accessdata.fda.gov (2025)
- 06European Medicines Agency. Increlex EPAR — Product Information (mecasermin). EMA (2024)
The reference sections above are imported from our compound knowledge base, which classes the evidence for IGF-1 LR3 as emerging. That classification is the knowledge base’s, not ours, our own grade appears only where an audit is linked above. Research use only; nothing here is medical advice or a protocol.
5-Amino-1MQ is a small molecule studied for its potential to help the body shrink fat cells and raise NAD+ levels without cutting appetite.
BPC-157 is a synthetic pentadecapeptide derived from a protective protein found in gastric juice. Studied in tissue-repair and regeneration research models.
Peptide bioregulator referenced for connective tissue support.
Peptide bioregulator referenced for nervous system support.
Combination research blend of CJC-1295 (no DAC) and Ipamorelin. Studied as a GHRH/GHRP combination in growth-hormone-axis research.
Peptide bioregulator referenced for pineal support.