Human Growth Hormone (HGH) vs IGF-1 LR3
A detailed comparison to help you understand the differences and choose the right peptide for your research goals.
Human Growth Hormone (HGH)
Human Growth Hormone (somatropin) is a 191-amino acid protein identical to naturally produced GH. FDA-approved for growth hormone deficiency, Turner syndrome, and other conditions. Widely used off-label for anti-aging and performance.
Full details →IGF-1 LR3
IGF-1 LR3 (Long R3 Insulin-like Growth Factor-1) is a modified version of IGF-1 with extended half-life and enhanced potency. The modifications prevent binding to IGF binding proteins, increasing bioavailability.
Full details →Side-by-Side Comparison
| Aspect | Human Growth Hormone (HGH) | IGF-1 LR3 |
|---|---|---|
| Dose Range | 200 mcg–2 mg | 20 mcg–100 mcg |
| Frequency | 1x daily | 1x daily |
| Cycle Length | 12–24 weeks | 4–6 weeks |
| Route | subcutaneous | subcutaneous |
| Mechanism | Binds to GH receptors throughout the body, stimulating IGF-1 production in the liver. Promotes protein synthesis, fat metabolism, and cellular regeneration across multiple tissues. | Binds to IGF-1 receptors to promote protein synthesis, muscle growth, and fat metabolism. The LR3 modification (13 amino acid extension and arginine substitution) extends half-life from minutes to 20-30 hours. |
| Typical Dosage | Medical: 0.1-0.3mg/kg/week divided into daily doses. Anti-aging: 1-2 IU daily. Performance: 2-6 IU daily, sometimes higher. | Research protocols typically use 20-100mcg daily, often divided into multiple injections or administered bilaterally to target muscles. |
| Administration | Subcutaneous injection, preferably at night to mimic natural pulsatile release. Rotate injection sites. Store refrigerated. | Intramuscular injection (site-specific growth) or subcutaneous for systemic effects. Often cycled 4-6 weeks on, equal time off. |
| Side Effects | Joint pain, water retention, carpal tunnel syndrome, potential insulin resistance, and acromegaly features with long-term high doses. | Hypoglycemia, joint pain, water retention, potential jaw/hand growth with extended use, and injection site reactions. |
| Best For |
What They Have in Common
Human Growth Hormone (HGH), IGF-1 LR3 are both commonly used for:
Key Differences
Unique to Human Growth Hormone (HGH):
Which Has Stronger Evidence?
- Fat Loss: Human Growth Hormone (HGH) has stronger research support.
- Recovery & Healing: Human Growth Hormone (HGH) has stronger research support.
| Goal | Human Growth Hormone (HGH) | IGF-1 LR3 |
|---|---|---|
| Muscle Growth | high | high |
| Fat Loss | high | medium |
| Recovery & Healing | high | medium |
Key Studies
Human Growth Hormone (HGH)
- Transgenic Artifacts Caused by Passenger Human Growth Hormone.
Trends in endocrinology and metabolism: TEM, 2018
- [Human growth hormone and Turner syndrome].
Anales de pediatria (Barcelona, Spain : 2003), 2017
- Significance of the disulphide bonds of human growth hormone.
Endokrynologia Polska, 2013
IGF-1 LR3
- IGF-1 LR3 does not promote growth in late-gestation growth-restricted fetal sheep.
American journal of physiology. Endocrinology and metabolism, 2025
- 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
- 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
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