IGF-1 LR3

What IGF-1 LR3 does

IGF-1 LR3 is a modified form of the growth signal IGF-1. People report using it for muscle growth and recovery. No human trial has established a dose, benefit or safety profile. Low blood sugar and unwanted tissue growth are concerns. Mecasermin research does not establish an LR3 dose.

• People report using it for muscle fullness and growth; no human trial has tested these benefits. (Reported by users)
• People report using it around workouts for recovery; recovery benefits in humans are unknown. (Reported by users)
• User reports are mixed: one reported muscle benefit, another no clear benefit. (Reported by users)

Uses in the sources

• Reported for muscle fullness and growth; no human trial has tested these benefits. (Reported by users) (source)
• Reported around workouts for recovery. Human injury-healing and recovery benefits are unknown. (Reported by users) (source)

IGF-1 LR3 dosage

Typical reported dose: 20–40 mcg once a day

• Reported 20–40 mcg daily: 20–40 mcg once daily once daily, under the skin. Reported by users, common report. Studied in: Adults discussing physique use. (source)
• Reported 50 mcg with breaks: 50 mcg per injection; the commenter did not state frequency not stated in this comment, under the skin. Reported by users, occasional report. Studied in: An adult forum commenter reporting SC use. (source)
• Reported 100 mcg into muscle: 100 mcg once daily once daily, into muscle. Reported by users, rare report. Studied in: An adult commenter reporting actual use. (source)
• Forum guide with longer cycles: 30–80 mcg daily, or a separate 50–120 mcg daily range once daily, under the skin. Reported by users, occasional report. Studied in: A community guide, not a clinical study. (source)
• One reported 20→40→60 mcg cycle: 20 mcg in week 1; 40 mcg in middle weeks; 60 mcg in the final week of a 5–6-week cycle before workouts; dosing frequency not stated, under the skin. Reported by users, rare report. Studied in: One 23-year-old man reporting SC pre-workout use. (source)

These are doses reported in labels, trials or user reports, not a personal plan. Check the source behind each one.

Work out syringe units with the dosing calculator

How to mix IGF-1 LR3

Comes as: Community-reported lyophilized powder vials.

Mixed with: Community posts use bacteriostatic water or discuss dilute acetic acid. No human-use diluent is established..

Common vial sizes: 1 mg. Common water amounts: 2, 3 mL.

• One guide describes 1 mg with 2 mL or 3 mL bacteriostatic water. These are community examples.
• Comments disagree about acid versus water and degradation. No validated sterility or stability data settle this.
• Mixing does not remove endotoxin, impurities or an incorrect peptide.

Before mixing: No validated human-use storage specification located.

After mixing: Posts advise refrigeration; a reliable post-mixing shelf life is unknown.

IGF-1 LR3 side effects and risks

Reported side effects

• Low blood sugar: LR3 rate unknown. Related mecasermin can cause severe low blood sugar., serious. Sweating, shaking, confusion or fainting need prompt blood sugar assessment. (source)
• Unwanted tissue or organ growth: Organ growth occurred in guinea pigs; human incidence is unknown., serious (source)
• Fluid retention, tingling or joint pain: Possible class effects; no LR3 specific human rate is available., moderate (source)
• Injection-site reactions or infection: No LR3 incidence estimate. Unregulated injectable quality adds risk., serious (source)
• Cancer-related concerns: A growth signalling concern, not a measured LR3 cancer rate., serious (source)

Stop and get help if

• Confusion, fainting, seizure or low blood sugar that persists: Stop exposure and get emergency care. Do not give food or drink to someone unconscious.
• Trouble breathing, facial swelling or widespread hives: Stop exposure and get emergency care.
• Severe headache with vomiting or new vision changes: Stop exposure and seek urgent care. Mecasermin, a related drug, can raise pressure around the brain.
• Chest pain, severe breathlessness or collapse: Get emergency care now.
• Fever with spreading redness, severe pain or swelling at an injection site: Seek urgent care for possible infection.

Who should avoid it

• pregnant: No human reproductive safety data.
• breastfeeding: Transfer into milk and infant effects are unknown.
• tryingToConceive: Reproductive safety is unknown. This is a precaution.
• under18: No human LR3 pediatric dose has been studied.
• activeCancer: Block active or suspected cancer because LR3 activates growth signalling.
• cancerHistory: Past cancer or a cancer-predisposing condition needs specialist review before growth-factor exposure.
• diabetes: LR3 may lower blood sugar. Human use in diabetes is unstudied.
• diabeticRetinopathy: Human IGF-1 research found worse diabetic eye disease. LR3 risk is unknown.
• seizureDisorder: Low blood sugar can trigger seizures. LR3 risk is unknown.
• sleepApnea: Related mecasermin can enlarge tonsils and obstruct breathing; LR3 risk is unknown.
• heartCondition: Swelling and heart effects need review. LR3 heart safety is unknown.
• kidneyDisease: No human LR3 clearance or dose-adjustment data.
• liverDisease: No human LR3 clearance or dose-adjustment data.
• surgeryPlanned: Fasting or blood sugar medicines need review for low blood sugar.
• other: Severe IGF-1 or ingredient allergy blocks re-exposure, as with related mecasermin.
• testedAthlete: WADA prohibits IGF-1 analogues at all times under S2.3.

Interactions

• Insulin: Expected additive low-blood-sugar risk. No LR3 interaction trial exists.
• Sulfonylureas and other insulin releasers: These medicines lower blood sugar; adding LR3 could compound that effect.
• Other IGF-1 products: LR3 combination safety is unknown.
• Growth hormone and GH secretagogues: People stack these to increase GH/IGF signalling. LR3 combination safety has not been studied.

Product quality risks

• A tested black-market vial contained LR3 with an extra His6 purification tag, not the expected finished molecule.
• A doping-laboratory report also identified unpurified LR3. Neither paper estimates today's market-wide failure rate.
• FDA found poor sterile-production practices at a facility that compounded LR3 among other unapproved products.

What to expect

No human LR3 study found on benefits, safety or how the body handles it. Animal and cell findings cannot establish human dosing.

Key studies

• LR3 structure and binding: LR3 is a distinct molecule with altered binding-protein interactions. (source)
• Organ growth in guinea pigs: Organ growth did not translate into greater overall growth. (source)
• Growth-restricted fetal sheep: LR3 did not improve fetal growth in this model. (source)

IGF-1 LR3 FAQ

• Is IGF-1 LR3 FDA-approved? No FDA-approved LR3 product. A research label is not authorization for human use.
• How do people take it? Under the skin, once daily. The review describes 4–6 weeks on followed by the same time off.. Source: reported by users, not an established dose.
• What's the difference between IGF-1 LR3 and Somatropin? IGF-1 LR3: an unapproved growth signal with no human trials found. Somatropin: prescription human growth hormone, with no proven anti-aging benefit. Why people pair them: people seek more growth signalling and muscle gain.
• Can I take it with Growth hormone? People seek more growth signalling and muscle gain. No LR3 combination trial; fluid retention and blood-sugar effects may add. Source: reported by users. Ask a doctor before combining anything.
• Is it banned in sport? Yes. It is banned in and out of competition (WADA 2026). IGF-1, mecasermin and IGF-1 analogues are prohibited in and out of competition.
• How long does a mixed vial last? Posts advise refrigeration; a reliable post-mixing shelf life is unknown.