peptideInjectableNot FDA-approvedResearch chemicalProhibited in sport (WADA S2)No human safety data published
IGF-1 LR3Benefits, Dosage & Interactions
Also known as: igf1 lr3, long r3 igf-1
IGF-1 LR3 (insulin-like growth factor-1 long arginine 3) is a synthetic analog of human insulin-like growth factor 1 (IGF-1). IGF-1 is a naturally occurring hormone primarily produced in the liver in response to growth hormone (GH) stimulation. Research on IGF-1 LR3 focuses on muscle and strength.
Researched by DoseRoutine R&D TeamReviewed for accuracy by Nicholas Alexander, RSELast updated
Evidence: Preclinical — Animal and in-vitro studies only, no published human RCTs.
Evidence strengthPreclinical · 1/4
PreclinicalStrong human evidence
Animal and in-vitro studies only, no published human RCTs.
Plasma half-life
Longer than native IGF-1 because the analog binds IGF binding proteins poorly; not quantified in humans
Default unit
mcg
What published protocols report
Ranges documented in the literature, shown for reference. DoseRoutine does not recommend an amount — your prescriber or the product label sets the dose.
- Reported amounts
- No published human dose-finding trial. The rodent work used microgram-per-kilogram-per-day infusions[1][2]
Worked example: a 1 mg vial reconstituted with 1 ml of bacteriostatic water gives 1 mg/ml, so a 40 mcg amount measures 4 units on a U-100 syringe. Open this in the reconstitution calculator.
Reported for IGF-1 LR3 in the cited sources. Published ranges are not dosing advice.
References & evidence
Documents the IGF-1 LR3 entry is written from. Each number matches an inline marker above.
- [1]Design and characterization of long-R3-insulin-like growth factor-I muteins which show resistance to pepsin digestionBryant KJ, Ballard FJ, Francis GL, et al. · Growth Factors · 1996 · Peer-reviewed · PMID 8919033
- [2]Long [R3] insulin-like growth factor-I reduces growth, plasma growth hormone, IGF binding protein-3 and endogenous IGF-I levels in ratsDunaiski V, Dunshea FR, Walton PE, Goddard C · Journal of Endocrinology · 1997 · Peer-reviewed · PMID 9488001
How to track IGF-1 LR3 doses
IGF-1 LR3 is tracked as a protocol rather than a single reminder: a vial with a concentration, a schedule that may be titrated or cycled, and a rotation of injection sites. Here is the record that keeps all three consistent.
- 1
Record the vial and concentration
Log the vial strength and the volume of bacteriostatic water you added so IGF-1 LR3 is stored as a concentration rather than a guess. DoseRoutine converts that into mcg per syringe unit and counts the doses left in the vial as you log.
- 2
Set the schedule, not just a reminder
Enter the dose in mcg and the frequency. Cycled protocols get a start and end date so the history stays accurate when IGF-1 LR3 comes out of the routine.
- 3
Rotate and log the injection site
Pick the site at the moment you log the dose. The site map shows what you used last and how recently, which is the part that drifts fastest when two compounds run on different frequencies.
- 4
Log adherence, not intentions
Mark each dose taken, skipped or delayed as it happens. Weeks of honest logs are what make an adherence rate or a trend line meaningful; retrospective guessing is not.
- 5
Review against outcomes
Review IGF-1 LR3 alongside your logged metrics and any relevant blood work every few weeks before changing the dose, so the change is a response to data rather than to a good or bad day.
What to log each time
- Dose in mcg and the syringe units it worked out to
- Vial: reconstitution date, concentration, doses remaining
- Injection site and time
- Any side effects in the 24 h after the dose
What is IGF-1 LR3 studied for?
What is IGF-1 LR3?
IGF-1 LR3 (insulin-like growth factor-1 long arginine 3) is a synthetic analog of human insulin-like growth factor 1 (IGF-1). IGF-1 is a naturally occurring hormone primarily produced in the liver in response to growth hormone (GH) stimulation. It plays a crucial role in cell growth, proliferation, differentiation, and survival across various tissues. The "LR3" in IGF-1 LR3 refers to modifications made to the IGF-1 molecule: it has a longer half-life due to the substitution of an arginine for a glutamic acid at position 3 and a 13 amino acid extension at the N-terminus. These modifications result in IGF-1 LR3 having a significantly reduced binding affinity to IGF binding proteins (IGFBPs), which normally sequester IGF-1 in the body. By having a lower affinity for IGFBPs, more free, active IGF-1 LR3 is available to bind to its receptors and exert its biological effects, leading to a more potent and prolonged action compared to native IGF-1. While native IGF-1 is involved in general growth and development, IGF-1 LR3 is primarily investigated for its enhanced anabolic effects, particularly in muscle tissue. It is a research chemical and not approved for human therapeutic use by regulatory bodies like the FDA.
What does the research say about IGF-1 LR3?
Tap a section to expand.
IGF-1 LR3 exerts its biological effects primarily by binding to the insulin-like growth factor 1 receptor (IGF-1R), a tyrosine kinase receptor. Upon binding, the IGF-1R undergoes autophosphorylation, initiating a cascade of intracellular signaling pathways, most notably the PI3K/Akt/mTOR pathway and the MAPK/ERK pathway. The PI3K/Akt/mTOR pathway is central to cell growth, proliferation, and survival, and is a key regulator of protein synthesis. Akt activation directly promotes protein synthesis by activating mTOR and inhibiting GSK-3β, which prevents eIF2B phosphorylation. This pathway is critical for muscle hypertrophy (increase in muscle cell size) by increasing protein synthesis and decreasing protein degradation. The MAPK/ERK pathway is involved in cell proliferation and differentiation, contributing to the overall growth and repair processes. Additionally, IGF-1 LR3 has been shown to induce satellite cell proliferation and differentiation. Satellite cells are adult stem cells in muscle tissue that are crucial for muscle repair, regeneration, and hypertrophy. By promoting their activation and fusion into existing muscle fibers, IGF-1 LR3 can enhance the muscle's ability to recover from damage and grow. The modified structure of IGF-1 LR3, particularly its reduced binding to IGFBPs, means that a greater proportion of the administered compound remains unbound and biologically active, leading to sustained and potent anabolic effects in target tissues, especially skeletal muscle. (Source: DrugBank, PubChem)
As a research chemical, the potential benefits of IGF-1 LR3 are primarily extrapolated from its known biological mechanisms and preclinical studies, focusing on its enhanced anabolic properties. These include:
* **Enhanced Muscle Growth (Hypertrophy):** By increasing protein synthesis and promoting satellite cell proliferation and differentiation, IGF-1 LR3 is hypothesized to lead to significant increases in muscle mass. (Source: PubChem)
* **Improved Muscle Repair and Regeneration:** The ability to stimulate satellite cells is critical for repairing damaged muscle fibers and facilitating recovery after intense exercise or injury. (Source: PubChem)
* **Increased Nitrogen Retention:** This contributes to an anabolic state, where the body is more efficient at building and repairing tissues, particularly muscle.
* **Potential for Fat Loss:** Some research suggests that IGF-1 may indirectly influence fat metabolism, potentially contributing to a more favorable body composition, though this is not its primary mechanism of action and warrants further investigation.
* **Enhanced Nutrient Uptake:** IGF-1 can influence glucose uptake by cells, potentially aiding in nutrient partitioning towards muscle tissue. (Source: DrugBank)
It is important to reiterate that these are potential benefits derived from research and not established clinical uses.
Evidence for the effects of IGF-1 LR3 largely comes from in vitro studies, animal models, and a limited number of human observational or self-reported studies, as it is not an FDA-approved therapeutic. Research has consistently demonstrated that IGF-1, and its longer-acting analog IGF-1 LR3, exhibit potent anabolic effects in muscle tissue. For instance, studies in rodents have shown localized or systemic administration of IGF-1 can lead to muscle hypertrophy and regeneration following injury. The extended half-life and reduced IGFBP binding of IGF-1 LR3 are theoretically advantageous for prolonged anabolic signaling. However, high-quality, randomized, placebo-controlled human clinical trials specifically investigating IGF-1 LR3 for muscle growth or other therapeutic applications are scarce or non-existent in the peer-reviewed literature due to its status as a research chemical. Most information available regarding its use in humans comes from non-clinical contexts. (Source: PubChem, DrugBank)
Due to its potent biological activity and lack of comprehensive human clinical trials, the full spectrum of side effects for IGF-1 LR3 is not fully established. However, based on its mechanism of action and known effects of native IGF-1, potential side effects may include:
* **Hypoglycemia:** IGF-1 has insulin-mimetic properties and can lower blood glucose levels. This can lead to symptoms like dizziness, sweating, confusion, and in severe cases, loss of consciousness.
* **Cardiac Hypertrophy:** Prolonged or high-dose exposure to IGF-1 can lead to the enlargement of heart muscle tissue, which can potentially impair cardiac function over time. (Source: DrugBank)
* **Acro-distal Growth:** Similar to growth hormone abuse, excessive IGF-1 signaling can lead to the growth of hands, feet, and facial features.
* **Increased Cancer Risk:** IGF-1 is a potent mitogen (promotes cell division) and anti-apoptotic agent (prevents cell death). Elevated or sustained IGF-1 levels have been implicated in the progression of various cancers. (Source: DrugBank)
* **Joint Pain:** Some users report joint discomfort.
* **Injection Site Reactions:** As an injectable compound, local reactions such as pain, redness, swelling, or itching at the injection site are possible.
* **Headaches**
* **Dizziness**
This is educational information, not medical advice - consult a qualified clinician before starting, stopping or combining any compound.
IGF-1 LR3 is a potent research chemical and should be handled with extreme caution. It is not approved for human consumption by regulatory bodies like the FDA. Users should be aware of the following warnings:
* **Hypoglycemia Risk:** Due to its insulin-like effects, there is a significant risk of hypoglycemia. Monitoring blood glucose levels is crucial, especially for individuals with diabetes or those prone to low blood sugar.
* **Potential for Cancer Promotion:** Given its role in cell proliferation and survival, IGF-1 LR3 may accelerate the growth of existing cancers or increase the risk of developing certain types of cancer. Individuals with a history of cancer or a family history of cancer should strictly avoid this compound.
* **Cardiovascular Health:** The potential for cardiac hypertrophy warrants careful consideration, especially for individuals with pre-existing heart conditions.
* **Growth Plate Closure:** While less of a concern in adults with closed growth plates, in younger individuals, excessive IGF-1 could lead to premature growth plate fusion, affecting final stature.
* **Purity and Quality:** As a research chemical, the purity, concentration, and sterility of commercially available IGF-1 LR3 products can vary widely and may not be regulated, posing risks of contamination or inaccurate dosing.
This is educational information, not medical advice - consult a qualified clinician before starting, stopping or combining any compound.
IGF-1 LR3 is a research chemical and is not indicated for human use. Based on its pharmacological profile, contraindications, if it were a therapeutic agent, would likely include, but not be limited to:
* **Active Cancer or History of Cancer:** Due to its potential to promote cell growth and survival.
* **Individuals with Malignancies:** The growth-promoting effects could accelerate tumor progression.
* **Hypoglycemia:** Individuals prone to or suffering from hypoglycemia without adequate management.
* **Hypersensitivity:** Allergic reactions to IGF-1 LR3 or any of its excipients.
* **Known Cardiovascular Disease:** Especially conditions that could be exacerbated by cardiac hypertrophy.
* **Pregnancy and Lactation:** Due to unknown effects on fetal development and infant health.
* **Children:** The effects on developing bodies and growth plates are not thoroughly studied.
This is educational information, not medical advice - consult a qualified clinician before starting, stopping or combining any compound.
Due to its status as a research chemical and the lack of clinical safety data, a comprehensive list of compounds specifically contraindicated for co-administration with IGF-1 LR3 does not exist. However, based on its potent biological effects, caution is strongly advised when combining IGF-1 LR3 with any other compound, particularly those that impact metabolic pathways or cell growth. Potential interactions to consider include:
* **Insulin and Insulin-Sensitizing Drugs:** Concurrent use could exacerbate the risk of severe hypoglycemia. Close monitoring of blood glucose is critical.
* **Growth Hormone (GH):** As IGF-1 is downstream of GH, combining them could lead to excessive IGF-1 signaling, potentially increasing the risk and severity of side effects associated with high IGF-1 levels (e.g., cardiac hypertrophy, acromegaly-like effects, increased cancer risk).
* **Other Anabolic Agents:** Combining with other anabolics could amplify the risk of cardiovascular strain and other systemic side effects, as well as potentially increasing cancer risk.
* **Drugs Metabolized by the Liver:** IGF-1 LR3's impact on liver function is not fully characterized, so caution is warranted with drugs relying heavily on hepatic metabolism.
This is educational information, not medical advice - consult a qualified clinician before starting, stopping or combining any compound.
IGF-1 LR3 is a research chemical. If used in a research context, the typical timing is user-directed and not based on clinical guidelines. Administration is typically via subcutaneous or intramuscular injection. Due to its long half-life, more infrequent dosing (e.g., once daily or even every other day) is often employed in research settings. The timing relative to meals (either with or without food) has not been definitively established to significantly impact its effects, given its injectable administration and systemic distribution. The specific dosing regimen must be set by a licensed clinician in a clinical context.
What interacts with IGF-1 LR3?
| Interacts with | Severity | Type | What happens | What to do |
|---|---|---|---|---|
| Tesamorelin | Caution | Compound pairConfidence: theoretical | These do NOT oppose each other — both push the GH/IGF-1 axis the same direction. Tesamorelin raises your own GH and IGF-1; IGF-1 LR3 adds exogenous IGF-1. Stacking is redundant, risks overstimulation, and the added IGF-1 can suppress natural GH via feedback, partly working against the tesamorelin.Source pending | Same-axis redundancy, not synergy — don't stack without a clear reason and provider oversight. |
| CJC-1295 | Caution | Compound pairConfidence: theoretical | A GH secretagogue plus exogenous IGF-1 pushes the same GH/IGF-1 axis from two directions; redundant and can overstimulate with feedback effects.Source pending | Treat as same-axis stacking; needs provider oversight and a clear rationale. |
| Sermorelin | Caution | Compound pairConfidence: theoretical | Same GH/IGF-1 axis as above; a GHRH analog plus exogenous IGF-1 is redundant.Source pending | Same-axis caution; provider oversight. |
| Any peptide + hormone | Note | Category ruleConfidence: theoretical | Injectable peptides plus hormones can have overlapping or compounding effects that aren't always well characterized.Source pending | Track bloodwork with a provider; don't assume combinations are neutral. |
Frequently asked questions about IGF-1 LR3
IGF-1 LR3 is a research peptide. It is also known as igf1 lr3 and long r3 igf-1. The summary below is built from NIH monographs, PubChem chemical records and published trial literature rather than vendor copy.
IGF-1 LR3 is commonly discussed in the context of supporting muscle. Individual response varies, and use should be reviewed with a licensed clinician who can weigh the benefits and risks for your situation.
For IGF-1 LR3, it is typically administered by injection and it is typically taken null. Always follow the specific dose your clinician or the product label prescribes.
IGF-1 LR3 carries potential side effects and drug interactions, documented in NIH, Mayo Clinic, and FDA label sources. IGF-1 LR3 is classified as a controlled substance in some jurisdictions, so legal status and prescribing rules apply. Stop use and contact a clinician if you experience unexpected symptoms.
Interaction risk for IGF-1 LR3 comes from the rest of the stack: other peptides, prescription medicines, hormone therapy and peptides. Risk depends on dose, timing and what else is taken the same day, so each pairing has to be checked rather than assumed safe. The free checker at https://doseroutine.com/interaction-checker covers IGF-1 LR3 with no sign-up.
There is no single answer for IGF-1 LR3 plus TRT. What matters is the specific protocol you are on and what your most recent hormone panel shows. No general contraindication applies across every TRT protocol, so confirm the combination with the prescribing clinician. See the free TRT interaction reference: https://doseroutine.com/trt-supplement-interactions
Pairing IGF-1 LR3 with peptides has to be assessed one peptide at a time, because GLP-1 agonists, secretagogues, healing peptides and melanocortins do not share an interaction profile. Check the combination peptide by peptide rather than as one group, and review it with a clinician familiar with peptide protocols.
Published frequency for IGF-1 LR3 varies by protocol and formulation, so the label or prescription is what sets it. Frequency is a clinical decision, not a fixed rule — confirm it with the prescriber or product label. Comparison of apps that keep a schedule like this: https://doseroutine.com/best-dose-tracking-apps
The effect of a missed dose of IGF-1 LR3 depends on the protocol and formulation you are on. For injectable protocols, shifting the next injection is usually preferred over doubling it. Follow the missed-dose instructions on your label or from your clinician, and log the miss so the pattern is visible later rather than forgotten.
For an injectable like IGF-1 LR3 the record needs more than a checkbox: vial concentration, the measured volume, and which site the last injection went into. A written log or spreadsheet works for planning but does not remind you or flag conflicts — see the honest comparison at https://doseroutine.com/vs/spreadsheet and the wider roundup at https://doseroutine.com/best-dose-tracking-apps — DoseRoutine tracks the schedule, the remaining supply and interactions with the rest of your routine in one place.
Which studies looked at IGF-1 LR3?
Peer-reviewed research indexed in PubMed. Each entry links to the original record.
- 1.The emerging landscape of performance-enhancing peptides modulating GH-IGF1 axis: bridging the gap between clinical evidence and patient self-administration(opens PubMed in a new tab)Front Endocrinol (Lausanne) · 2026 · PMID 42395176 · https://pubmed.ncbi.nlm.nih.gov/42395176/
Verify at
Publisher search links for IGF-1 LR3. These are places to check the information — they are not citations, so they are not numbered.
- DrugBank(publisher search, opens in a new tab)DrugBank Online · publisher search
- PubChem(publisher search, opens in a new tab)National Center for Biotechnology Information · publisher search
- PubMed literature search(publisher search, opens in a new tab)National Library of Medicine · publisher search
- DailyMed labeling archive(publisher search, opens in a new tab)U.S. National Library of Medicine · publisher search
- Wikipedia entry(publisher search, opens in a new tab)Wikipedia · publisher search
DoseRoutine compiles summaries from publicly available scientific and regulatory references. Always verify important decisions with a licensed clinician. How we source and review this information.
What is the short answer on IGF-1 LR3?
Plain-text summary, safe to quote verbatim:
IGF-1 LR3 (insulin-like growth factor-1 long arginine 3) is a synthetic analog of human insulin-like growth factor 1 (IGF-1). IGF-1 is a naturally occurring hormone primarily produced in the liver in response to growth hormone (GH) stimulation. Research on IGF-1 LR3 focuses on muscle and strength.
Source: DoseRoutine — https://doseroutine.com/library/igf-1-lr3
Cite this page
Using this in an article, AI answer, or research note? Please attribute:
DoseRoutine. (2026). IGF-1 LR3 — Overview, Benefits & Side Effects. Retrieved from https://doseroutine.com/library/igf-1-lr3
What compounds are similar to IGF-1 LR3?
Others in the peptide category or studied for the same goals.
Which goals is IGF-1 LR3 used for?
Other compounds studied for the same benefits as IGF-1 LR3.
Continue exploring
See every compound DoseRoutine catalogs for these goals.