← Back to Encyclopedia
01 / IDENTITY
Compound Profile
CLASSIFICATION
Linear tridecapeptide; synthetic analog of α-MSH (alpha-melanocyte stimulating hormone). Unlike MT-II which is cyclic, MT-I is a linear peptide that selectively targets MC1-R only.
RECEPTOR
MC1-R ONLY — melanocytes → melanin production → tanning + UV protection
Does NOT activate:
✗ MC3R (no appetite effects)
✗ MC4R (no sexual/erectile effects)
✗ MC5R (no sebaceous gland effects)
✗ Does NOT cross the blood-brain barrier
DEVELOPED BY
University of Arizona — Dr. Mac Hadley & Dr. Victor Hruby, 1980s. Originally designed as a skin cancer prevention tool. Later developed by Clinuvel Pharmaceuticals as Scenesse® (16mg implant).
FDA STATUS
FDA APPROVED — October 2019
Scenesse® approved for erythropoietic protoporphyria (EPP), a rare condition causing extreme sun sensitivity and pain. The first melanocortin-based drug to receive FDA approval.
KEY DISTINCTION
MT-I = tanning + UV protection ONLY. MT-II = tanning + libido + appetite changes. If your goal is ONLY tanning/sun protection, MT-I is the safer, more targeted choice.
02 / HEAD-TO-HEAD COMPARISON
Melanotan I vs Melanotan II
RECEPTORMC1-R only (selective)
TANNING✅ Yes
UV PROTECTION✅ Yes — increases eumelanin
SEXUAL EFFECTS❌ None
APPETITE❌ No change
NAUSEAMild
CROSSES BBB❌ No
FDA APPROVED✅ Yes (Scenesse)
SAFETYSuperior
BEST FORTanning + sun protection
RECEPTORMC1R + MC3R + MC4R + MC5R
TANNING✅ Yes
UV PROTECTION✅ Yes — same mechanism
SEXUAL EFFECTS✅ Strong (erections, arousal)
APPETITESuppressed
NAUSEAModerate-severe
CROSSES BBB✅ Yes
FDA APPROVED❌ No
SAFETYMore side effects
BEST FORTanning + libido/ED
Bottom line: If you want ONLY tanning and UV protection — use MT-I. It's safer, more targeted, and has FDA approval backing its safety profile. Only use MT-II if you specifically want the sexual/libido effects.
03 / MECHANISM
How Melanotan I Works
01
Binds MC1-R on Melanocytes
MT-I is a synthetic copy of α-MSH — a hormone your body already makes. It selectively binds to MC1-R receptors on melanocytes (pigment-producing cells in your skin). Every human has roughly the same NUMBER of melanocytes — MT-I makes them MORE ACTIVE.
02
Activates cAMP → MITF → Tyrosinase Pathway
MC1-R activation triggers a signaling cascade: cAMP increases → MITF transcription factor activates → tyrosinase enzyme production ramps up. Tyrosinase is the rate-limiting enzyme for melanin production. Once elevated, melanin production continues for DAYS after the MT-I has cleared your blood.
03
Increases EUMELANIN Specifically
Two types of melanin: eumelanin (brown/black — protective) and pheomelanin (red/yellow — actually INCREASES UV damage). MT-I specifically increases eumelanin production. This is critical — you're not just getting darker, you're getting darker with the RIGHT type of melanin.
04
Melanosomes Shield Your DNA
Melanocytes package eumelanin into melanosomes and transfer them to surrounding skin cells. These melanosomes position themselves ABOVE the cell nucleus like tiny umbrellas — physically shielding your DNA from UV radiation. This is your body's built-in defense. MT-I turns up the volume.
04 / UV PROTECTION
The Science of Natural Sun Protection
01
Longer Time to Sunburn
Research shows MT-I increases the Minimum Erythemal Dose (MED) by 50-75% in fair-skinned individuals. Someone who burns in 20 minutes may not burn until 35-40 minutes. Combined with sunscreen, you get protection from BOTH outside (SPF) and inside (melanin).
02
UV Absorption + Free Radical Scavenging
Eumelanin absorbs UV photons directly, converting UV energy into harmless heat with >99.9% efficiency. It also neutralizes reactive oxygen species (ROS) generated by UV exposure — the same free radicals that cause skin aging and DNA mutations.
03
Reduced UV-Induced DNA Damage
Higher eumelanin content correlates with 10-100× lower rates of UV-induced DNA mutations. Eumelanin also supports faster repair of cyclobutane pyrimidine dimers (CPDs) — the DNA lesions that lead to skin cancer mutations.
MT-I is NOT sunscreen. It enhances your body's natural UV defense but does not replace sunscreen, protective clothing, or shade. Use MT-I AS PART OF a comprehensive sun protection strategy, not instead of one. Always monitor moles and freckles — get 6-month skin checks while using any melanocortin peptide.
05 / DOSING PROTOCOL
Tanning Protocol
Vial: 10mg · BAC Water: 2mL · Concentration: 5,000 mcg/mL (1 unit = 50 mcg)
| PHASE | DOSE | FREQUENCY | DURATION | NOTES |
|---|
| LOADING — Start |
250 mcg
5 units |
Daily |
Day 1–3 |
Start here. Assess tolerance. Mild nausea possible. |
| LOADING — Ramp |
500 mcg
10 units |
Daily |
Day 4–7 |
Double if day 1-3 tolerated well. |
| LOADING — Peak |
750–1000 mcg
15–20 units |
Daily |
Week 2 |
Optional. Many stay at 500 mcg. Visible tanning begins. |
| ✅ MAINTENANCE |
500–1000 mcg
10–20 units |
2× per week |
Ongoing |
Maintain your tan indefinitely. Pigmentation fades in 4-8 weeks if stopped. |
Injection Technique: SubQ (subcutaneous) injection. Rotate sites: abdomen, thigh, upper arm. Inject slowly to reduce stinging. 30-90 minutes before UV exposure for maximum melanin priming.
After Stopping: No withdrawal effects. Pigmentation fades gradually over 4-8 weeks as melanin naturally turns over. No rebound. Can restart anytime — full results return within 7-10 days.
06 / SEASONAL STRATEGY
Year-Round Protocol
🌱 SPRING (March–April)
Start loading phase. Build your base tan before summer UV ramps up. This is the ideal time to begin — melanin takes 2-3 weeks to fully develop.
☀️ SUMMER (May–September)
Maintenance 2×/week. Your melanin is at peak. 30 minutes of sun does what 2-3 hours used to. Combined UV protection from melanin + sunscreen = maximum defense.
🍂 FALL (October)
Taper to 1×/week. UV exposure drops naturally. Your tan will hold longer than without MT-I. Optional to continue through fall.
❄️ WINTER (November–February)
Off season. Stop MT-I. Pigmentation fades naturally over 4-8 weeks. No need to maintain a tan when UV exposure is minimal. Resume in March.
07 / SIDE EFFECTS
What to Expect
⚡
Nausea (mild — loading phase only)
Most common side effect. Usually resolves within 30-60 minutes. Significantly milder than MT-II. Dose-dependent — staying at 250-500 mcg minimizes this.
⚡
Facial Flushing
Temporary warmth/redness in the face. Histamine-related. Usually resolves within 1-2 hours. More common during loading.
⚠️
Darkening of Moles & Freckles
Existing moles and freckles may darken. This is expected — melanocytes in those areas are already more active. Monitor all moles for changes in shape, border, or asymmetry. Get a skin check every 6 months while using any melanocortin peptide.
What MT-I does NOT cause (unlike MT-II):
❌ No spontaneous erections
❌ No sexual arousal changes
❌ No appetite suppression
❌ No yawning/fatigue
❌ Does not cross the blood-brain barrier
SOURCES
· PeptideDeck — MT-I vs MT-II Full Comparison Guide (2026)
· RealPeptides — Melanotan I Dosing Protocol
· FDA Scenesse® Prescribing Information (October 2019)
· Peptides.org — Melanotan I Dosage Calculator
· Photoprotection research literature — eumelanin UV absorption studies
· Clinuvel Pharmaceuticals — Scenesse clinical trial data (EPP)
⚠ RESEARCH & EDUCATIONAL USE ONLY. Apex Protocol LLC is not a licensed medical provider. Nothing on this platform constitutes medical advice, diagnosis, or treatment. All peptide compounds referenced are research chemicals not approved by the FDA for human use (Scenesse® implant is FDA-approved for EPP only — not the injectable research form). Information is provided solely for educational purposes based on publicly available scientific literature. Always consult a qualified medical professional before beginning any new health protocol.