IGF-1 LR3 vs Melanotan II
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 →Melanotan II
Melanotan II is a synthetic peptide analog of α-MSH with broader receptor activity than Melanotan I. It produces tanning effects and has notable effects on sexual function and appetite suppression.
Full details →Side-by-Side Comparison
| Aspect | IGF-1 LR3 | Melanotan II |
|---|---|---|
| Dose Range | 20 mcg–100 mcg | 250 mcg–1 mg |
| Frequency | 1x daily | 1x daily |
| Cycle Length | 4–6 weeks | 1–2 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. | Non-selective melanocortin receptor agonist affecting MC1R (tanning), MC3R and MC4R (sexual function and appetite). This broader activity explains its multiple effects beyond tanning. |
| Typical Dosage | Research protocols typically use 20-100mcg daily, often divided into multiple injections or administered bilaterally to target muscles. | Typical protocols: 0.25-0.5mg daily during loading phase for 1-2 weeks, then 0.5-1mg before UV exposure for maintenance. Start low to assess tolerance. |
| Administration | Intramuscular injection (site-specific growth) or subcutaneous for systemic effects. Often cycled 4-6 weeks on, equal time off. | Subcutaneous injection. Usually combined with UV exposure for tanning effects. Nasal spray formulations exist but have lower bioavailability. |
| Side Effects | Hypoglycemia, joint pain, water retention, potential jaw/hand growth with extended use, and injection site reactions. | Nausea (common initially), facial flushing, spontaneous erections, increased libido, appetite suppression, and mole darkening. |
| Best For |
What They Have in Common
IGF-1 LR3, Melanotan II are both commonly used for:
Key Differences
Unique to IGF-1 LR3:
Unique to Melanotan II:
Which Has Stronger Evidence?
- Fat Loss: IGF-1 LR3 has stronger research support.
| Goal | IGF-1 LR3 | Melanotan II |
|---|---|---|
| Fat Loss | medium | low |
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
Melanotan II
- Melanotan II nasal spray: a possible risk factor for oral mucosal malignant melanoma?
International journal of oral and maxillofacial surgery, 2025
- Melanotan II User Experience: A Qualitative Study of Online Discussion Forums.
Dermatology (Basel, Switzerland), 2021
- Melanotan II, a melanocortin agonist, partially rescues the impaired thermogenic capacity of pituitary adenylate cyclase-activating polypeptide deficient mice.
Experimental physiology, 2021
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