IGF-1 LR3 (Long R3 IGF-1) is a modified analog of insulin-like growth factor 1 with an Arg3 substitution and a 13-amino acid extension that significantly reduces IGF-binding protein binding. This increases free bioactive exposure and extends half-life compared with native IGF-1.

How is IGF-1 LR3 different from HGH?

HGH acts upstream by stimulating growth hormone receptors and raising IGF-1 production over time, while IGF-1 LR3 acts more directly at the IGF-1 receptor. In practice, HGH is typically used for longer endocrine modulation, while IGF-1 LR3 is often used in shorter cycles focused on anabolic and recovery outcomes.

What is a typical IGF-1 LR3 protocol?

Research protocols commonly start around 20 mcg daily, then titrate to 40-80 mcg daily based on tolerance and goals. Advanced users may use higher short-term ranges. Many protocols cap cycle length and include washout periods to reduce receptor desensitization risk.

What monitoring is important with IGF-1 LR3?

Blood glucose monitoring is important because IGF-1 LR3 can alter glucose handling and increase hypoglycemia risk in some users. Monitoring edema, joint discomfort, and overall recovery response is also common in supervised settings.

IGF-1 LR3: Dosing, Side Effects & FDA Status

What is IGF-1 LR3?

IGF-1 LR3 (Long R3 Insulin-like Growth Factor-1) is a recombinant analog of IGF-1 with an Arg3 substitution and a 13-amino acid N-terminal extension. These modifications dramatically reduce binding to IGF-binding proteins (IGFBPs), resulting in a ~20–30 hour half-life (vs. 12–15 hours for native IGF-1) and significantly greater tissue exposure and anabolic potency. Research only; not FDA-approved.

Mechanism of Action

Full IGF-1 receptor (IGF1R) agonism; reduced IGFBP binding increases free bioavailable fraction; activates PI3K/Akt/mTOR for protein synthesis and cell proliferation; promotes glucose uptake and satellite cell activation

Target: IGF-1 receptor (IGF1R), PI3K/Akt/mTOR pathway

Research / educational reference. Educational research index only — not medical advice. Literature maturity is not a verdict on whether a compound works in people. Community reports are not evidence of efficacy.

Evidence at a glance

Derived · maturity-1.0

Human efficacy is unproven unless an approved label or completed published efficacy program says otherwise. Counts reflect indexed literature volume/kind — never a verdict on effect.

Literature maturity

nascent 15/100

PubMed hits

CT.gov trials

Strong-human apps

Sample papers

Sample articles by era

2021-20232
2024-20262

Application grades (curated)

Human-grade apps0
Animal / in-vitro1
Mechanistic0

Does literature support studied applications?

Grades reflect cited literature posture — not a treatment recommendation. Community notes are never efficacy evidence.

Application	Cited evidence	Grade	Community
IGF-1 receptor anabolic signaling	Clear receptor biology; LR3 research-use human efficacy/safety is not an approved therapy claim.	Animal / in-vitro	Community reports vary; not evidence of efficacy.

Pharmacology

Mechanism of action

•Full IGF-1 receptor (IGF1R) agonism; reduced IGFBP binding increases free bioavailable fraction; activates PI3K/Akt/mTOR for protein synthesis and cell proliferation; promotes glucose uptake and satellite cell activation
•Primary target framing: IGF-1 receptor (IGF1R), PI3K/Akt/mTOR pathway

Half-life

20–30 hours

Identity & chemistry

Storage & stability

Lyophilized: 2–8°C; lyophilized typical shelf 12–24 months
Reconstituted: 2–8°C; in-use window often 14–30 days (product-dependent)
Tell-tale degradation: !Cloudiness, clumping, or particles after mixing
!Discoloration versus the expected clear/colorless (or labeled) solution
!Failed or incomplete reconstitution of lyophilized cake

Educational estimates. Prefer product labeling and peptide shelf-life tool.

Lab handling posture

Research / educational handling notes only. Not a substitute for an SDS.

•Use PPE appropriate for peptide powder/solution handling
•Avoid inhalation of lyophilized powder; handle spills per institutional policy
•Do not present research materials as medicines

Sample indexed literature

Recombinant expression of IGF-1 and LR3 IGF-1 fused with xylanase in Pichia pastoris.
Applied microbiology and biotechnology · 2023 · PMID 37261455
IGF-1 LR3 does not promote growth in late-gestation growth-restricted fetal sheep.
American journal of physiology. Endocrinology and metabolism · 2025 · PMID 39679943
Attenuated glucose-stimulated insulin secretion during an acute IGF-1 LR3 infusion into fetal sheep does not persist in isolated islets.
Journal of developmental origins of health and disease · 2023 · PMID 37114757
Revolutionary decellularized Alstroemeria stem-based nerve conduit integrated with GelMA and controlled IGF-1 LR3 release for enhanced rat sciatic nerve regeneration.
International journal of biological macromolecules · 2025 · PMID 41015370

Research Indications

Growth Hormone SupportMost Effective

Stimulates natural GH release through pituitary signaling pathways

Body CompositionEffective

Associated with increased lean mass and reduced body fat

Recovery & RepairEffective

Supports tissue repair and recovery from exercise or injury

Sleep QualityModerate

Some protocols show improvements in slow-wave and restorative sleep

Research Protocols

These are commonly discussed research protocols — not medical advice. Consult a healthcare provider before use.

Goal	Dose	Frequency	Route
Conservative Start (Week 1-2)	20 mcg	Once daily	Subcutaneous injection
Standard Body Comp Range	40-80 mcg	Once daily	Subcutaneous injection
Advanced Short Cycle	80-120 mcg	Once daily	Subcutaneous injection

Peptide & Drug Interactions

Always consult your healthcare provider before combining with other compounds. Use our Interaction Checker for reference.

Insulin / IGF-1Monitor

CorticosteroidsCaution

Thyroid HormonesMonitor

BPC-157Compatible

TB-500Compatible

Ipamorelin + CJC-1295 (synergistic combo)Compatible

Somatostatin AnalogsAvoid

How to Reconstitute & Inject

Use bacteriostatic (BAC) water only. Avoid saline — may cause precipitation. Refrigerate and use within 28 days.

1
Remove IGF-1 LR3 vial from refrigeration and allow to reach room temperature (15–20 minutes)
2
Clean vial top with alcohol swab and allow to air dry completely
3
Using a sterile syringe, draw the calculated volume of bacteriostatic water (BAC water)
4
Inject BAC water slowly down the side of the vial — do not aim directly at the powder
5
Gently swirl in circular motions — DO NOT shake vigorously as this degrades the peptide
6
Allow 2–3 minutes for full dissolution — solution should be clear and colorless
7
Draw calculated dose into an insulin syringe for subcutaneous injection
8
Inject into abdomen, thigh, or upper arm. Rotate injection sites to prevent lipodystrophy
9
Store reconstituted solution refrigerated (2–8°C) and use within 28 days

What to Expect

Week 1–2

Improved sleep quality may begin. Mild water retention possible initially.

Week 2–4

Deeper sleep, improved recovery. Appetite may increase slightly.

Week 4–8

Noticeable improvements in body composition, energy, and recovery speed.

Week 8–12

Skin quality improvements, reduced body fat, increased lean mass becoming visible.

Week 12+

Sustained improvements in body composition, strength, and overall vitality.

Side Effects & Safety

Water retention and mild bloating, especially early in protocol
Increased appetite (particularly with GHRP compounds)
Flushing or warmth at injection site
Tingling or numbness (carpal tunnel-like symptoms at higher doses)
Fatigue or lethargy if dosed at suboptimal times
Cortisol and prolactin elevation possible (especially GHRP-6)
Rare: Elevated blood glucose — monitor if diabetic or pre-diabetic

FDA Status & Regulatory Info

Research Only

Rx Required: No

503A Ban: No

Telehealth: N/A

Full FDA Status Tracker

Frequently Asked Questions

Research References

External links for education only. We do not control third-party content.

Community-reported data

The information below reflects self-reported experiences from PeptIQ app users. It is not clinical evidence and should not replace professional medical advice.

Community Intelligence

What 30 users report

30 community reports

Overall experience

From check-in ratings — separate from side effects logged below. Side effects are logged separately from overall experience. A favorable check-in can still include nausea, fatigue, or injection-site reactions.

Favorable 97% · Mixed 3% · Unfavorable overall 0%

Most reported benefits

Benefits users selected when logging a favorable or mixed check-in.

Recovery

171

Most logged side effects

Side effects are logged separately from overall experience. A favorable check-in can still include nausea, fatigue, or injection-site reactions.

Water retention

Self-reported dose per injection

Median bucket: 50–100 mcg · Most common: 10–25 mcg

Reports span 0–200 mcg

0–10

10–25

25–50

50–100

100–200

Anonymized self-reports from PeptIQ users — not prescribing guidance. Buckets group similar logged amounts; open-ended top buckets mean “at least” that dose.

Commonly stacked with

How repeat users are trending

Among repeat reporters, 96% said they felt similar to their last entry, 4% more positive, and 0% more negative.

Overall, repeat reporters leaned more positive than their previous entry.

Median gap between entries: 153 days · Based on 28 repeat reporters

Share Your Experience

Rate IGF-1 LR3 in the PeptIQ app and help the community make informed decisions.

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Educational information only

This page is for educational reference. It is not medical or legal advice. PeptIQ does not sell peptides or list vendors. Consult the FDA and a licensed healthcare professional for current regulations and individualized guidance.

IGF-1 LR3