IGF-1 LR3 vs Sermorelin
A detailed comparison to help you understand the differences and choose the right peptide for your research goals.
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 →Sermorelin
Sermorelin is a synthetic analog of GHRH consisting of the first 29 amino acids of the natural hormone. It was previously FDA-approved for GH deficiency diagnosis and treatment in children.
Full details →Side-by-Side Comparison
| Aspect | IGF-1 LR3 | Sermorelin |
|---|---|---|
| Dose Range | 20 mcg–100 mcg | 100 mcg–300 mcg |
| Frequency | 1x daily | 1x daily |
| Cycle Length | 4–6 weeks | 8–12 weeks |
| Route | subcutaneous | subcutaneous |
| Mechanism | 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. | Binds to GHRH receptors in the pituitary gland to stimulate natural GH production and release. Maintains the body's natural feedback mechanisms for GH regulation. |
| Typical Dosage | Research protocols typically use 20-100mcg daily, often divided into multiple injections or administered bilaterally to target muscles. | Typical dosing: 200-500mcg administered once daily, usually before bed. Some protocols use twice daily dosing. |
| Administration | Intramuscular injection (site-specific growth) or subcutaneous for systemic effects. Often cycled 4-6 weeks on, equal time off. | Subcutaneous injection, preferably at bedtime to work with natural GH release patterns. Can be combined with GHRPs for synergistic effects. |
| Side Effects | Hypoglycemia, joint pain, water retention, potential jaw/hand growth with extended use, and injection site reactions. | Generally well-tolerated. May cause injection site reactions, headache, flushing, or dizziness. Less side effects than direct GH administration. |
| Best For |
What They Have in Common
IGF-1 LR3, Sermorelin are both commonly used for:
Key Differences
Unique to Sermorelin:
Which Has Stronger Evidence?
- Muscle Growth: IGF-1 LR3 has stronger research support.
| Goal | IGF-1 LR3 | Sermorelin |
|---|---|---|
| Muscle Growth | high | medium |
| Fat Loss | medium | medium |
| Recovery & Healing | medium | medium |
Key Studies
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
Sermorelin
- A potentially effective drug for patients with recurrent glioma: sermorelin.
Annals of translational medicine, 2021
- Sermorelin: a better approach to management of adult-onset growth hormone insufficiency?
Clinical interventions in aging, 2006
- Sermorelin: a review of its use in the diagnosis and treatment of children with idiopathic growth hormone deficiency.
BioDrugs : clinical immunotherapeutics, biopharmaceuticals and gene therapy, 1999
Ready to Learn More?
Looking for trusted sources?