Question 1

What is IGF-1 LR3?

Accepted Answer

IGF-1 LR3 (Long Arginine-3 IGF-1) is a synthetic, longer-acting analog of human insulin-like growth factor 1. It carries an arginine substitution at position 3 and a 13-amino-acid N-terminal extension, giving it 83 amino acids total versus 70 for native IGF-1. The structural changes lower its affinity for IGF binding proteins and stretch its half-life to roughly 20-30 hours. It is sold as a research reagent and is not FDA-approved for any human use.

Question 2

What is the half-life of IGF-1 LR3?

Accepted Answer

Approximately 20-30 hours, compared to roughly 12-15 hours for native IGF-1. The longer half-life is the reason once-daily dosing is the standard schedule across research-community protocols.

Question 3

What dose ranges appear in IGF-1 LR3 research protocols?

Accepted Answer

Research-community sources cluster between 20 and 100 mcg per day, given as one daily SubQ or IM injection. Lower-end ranges (20-40 mcg/day) are most commonly cited for tolerance assessment and women's protocols. Above roughly 50-60 mcg/day, observed effect frequency rises faster than the perceived signaling benefit. None of these ranges are validated clinical doses.

Question 4

How is IGF-1 LR3 reconstituted?

Accepted Answer

Add bacteriostatic water to the lyophilized vial, pouring slowly down the inside wall — never directly onto the powder. Swirl gently, do not shake. Refrigerate immediately at 2-8°C. A 1 mg vial reconstituted with 2 mL of BAC water gives 500 mcg/mL; a 50 mcg dose at that concentration is 0.10 mL (10 units on a U-100 insulin syringe). For custom math, use the Pep Pal calculator .

Question 5

What is the standard cycle length?

Accepted Answer

Most research-community protocols cap on-time at 4-6 weeks with at least equal time off between cycles. The ceiling reflects observed patterns of progressive insulin resistance, organ-growth concern, and IGF-1 receptor desensitization. Continuous multi-month use is widely discouraged.

Question 6

How real is the hypoglycemia risk?

Accepted Answer

Very real. In the Increlex (native mecasermin) FDA-approved program, hypoglycemia was reported in 42% of subjects, with five subjects experiencing severe episodes requiring assistance and four experiencing seizures or loss of consciousness. The rate was highest in the first month. Mitigation is consistent across all sources: eat 30-50 grams of fast-acting carbohydrates within 30 minutes of every injection, never inject fasted, never inject before sleep, and keep glucose tablets accessible during cycles.

Question 7

Should IGF-1 LR3 be injected SubQ or IM?

Accepted Answer

Both routes are used in research protocols. SubQ is simpler and is the most-cited default. IM injection into a freshly trained muscle is reported in research interest in localized hyperplasia signaling, though the long half-life means the peptide distributes systemically regardless of site. Same hypoglycemia rules apply to both routes.

Question 8

Can IGF-1 LR3 be combined with insulin?

Accepted Answer

No. The combination produces additive hypoglycemia and has been associated with hospitalizations in research-community reporting. Both compounds lower blood glucose and the combined effect is unpredictable. This is treated as an absolute contraindication across virtually every published research-community source.

Question 9

Does IGF-1 LR3 increase cancer risk?

Accepted Answer

IGF-1 signaling is mitogenic and anti-apoptotic — both relevant to cancer biology. The Increlex label cites preclinical 2-year rat carcinogenicity studies in which increased mammary and skin tumor incidence occurred at high IGF-1 exposure. Tomas et al. (1997) reported that IGF-1 LR3 increased tumor growth in tumor-bearing catabolic rats. Epidemiological literature (LeRoith 2003; Pollak 2008) has linked elevated circulating IGF-1 to higher risk of certain cancers in human cohorts. Anyone with active or prior cancer, or strong family history, should not use IGF-1 LR3.

Question 10

Why never inject IGF-1 LR3 before bed?

Accepted Answer

Two reasons. First, hypoglycemic episodes during sleep are harder to detect and respond to. Second, exogenous IGF-1 can suppress the natural overnight GH pulse through hypothalamic-pituitary feedback. Most research protocols schedule injections at least 2-3 hours before bedtime.

Question 11

What vial sizes are common?

Accepted Answer

1 mg (1,000 mcg) and 0.1 mg (100 mcg) lyophilized vials are the most common research-grade sizes. The 1 mg vial is more practical for full cycles; 0.1 mg vials are usually used for short cycles or first-time tolerance assessment.

Question 12

Is IGF-1 LR3 FDA-approved?

Accepted Answer

No. IGF-1 LR3 is not FDA-approved for any human therapeutic use. The closest FDA-approved IGF-1 product is mecasermin (Increlex) , native recombinant human IGF-1, approved only for the long-term treatment of growth failure in pediatric patients with severe primary IGF-1 deficiency or GH gene deletion with neutralizing antibodies. There is no adult or performance-related FDA indication for any IGF-1 product.

Question 13

Is IGF-1 LR3 banned by WADA?

Accepted Answer

Yes. IGF-1 LR3 falls under the World Anti-Doping Agency's S2 category (peptide hormones, growth factors, related substances, and mimetics) and is prohibited at all times — both in and out of competition. Mongongu et al. (2020) published a validated detection method for IGF-1 LR3 in athlete samples.

Phase	Daily reference amount	Units / volume
Weeks 1–2	20 mcg (0.02 mg)	6 units (0.06 mL)
Weeks 3–4	40 mcg (0.04 mg)	12 units (0.12 mL)
Weeks 5–8	50 mcg (0.05 mg)	15 units (0.15 mL)

IGF-1 LR3.

Calculated volume reference

Cited protocol & reconstitution guide