Melanotan-2 vs PT-141 (Bremelanotide)
A synthetic copy of the hormone that switches on tanning. Small human trials found it darkened skin without sun exposure and triggered erections in men with erectile dysfunction. It has never been approved by any regulator.
The first FDA-approved peptide that works through your brain to reignite sexual desire—think of it as flipping the 'on' switch for arousal rather than just boosting blood flow like traditional ED meds.
Written by Michael Carroll — Owner, Director of Research · Reviewed by the Peptide Initiative Research Team · Editorial standards
Quick comparison
Dose range
Melanotan-2
0.5–0.5 mg
PT-141 (Bremelanotide)
1.75–1.75 mg
Frequency
Melanotan-2
Once daily
PT-141 (Bremelanotide)
As needed
Administration
Melanotan-2
Subcutaneous injection
PT-141 (Bremelanotide)
Subcutaneous injection
Cycle length
Melanotan-2
4-6 weeks
PT-141 (Bremelanotide)
Ongoing/indefinite
Onset speed
Melanotan-2
Moderate (1-2 weeks)
PT-141 (Bremelanotide)
Rapid (hours to days)
Evidence level
Melanotan-2
Limited human trials
PT-141 (Bremelanotide)
Strong human trials (Phase 3 or FDA approved)
Benefit ratings
Tanning Efficacy
Sexual Function
Tan Longevity
Sexual Desire
On-Demand Use
Clinical Evidence
Compound specifications
Melanotan-2
Molecular formula
C50H69N15O9
Molecular weight
1024.18 g/mol
Half-life
No human value published. In mice, plasma clearance after injection was rapid; no human pharmacokinetic study located.
Bioavailability
Completely absorbed by subcutaneous injection in humans for the related peptide melanotan-I; not separately measured for melanotan-II in humans
CAS number
121062-08-6
PT-141 (Bremelanotide)
Molecular formula
C50H68N14O10
Molecular weight
1025.2 g/mol
Half-life
2.7 hours
Bioavailability
~100% (subcutaneous injection)
CAS number
189691-06-3
Dosing compared
Melanotan-2
Subcutaneous
0.25 mg (250 mcg)
Once daily · First 3-5 days (loading)
Community-reported starting dose, not peer-reviewed. No clinical trial used a flat 0.25 mg dose. The published human trials dosed by body weight at 0.01-0.03 mg/kg subcutaneously in 3 healthy men [1]. Mild nausea was reported at most dose levels in that trial, which is what starting low is commonly described as managing [1].
0.5 mg (500 mcg)
Once daily · Continue loading 7-14 days until desired pigmentation
Community-reported loading dose, not peer-reviewed. The dose used in every published human trial was 0.025 mg/kg subcutaneously, about 1.75 mg for a 70 kg adult, given to 3 healthy men [1] and to 20 men with erectile dysfunction [4][6][7]. Subcutaneous is the only route with human trial evidence [1]. In the phase-I trial, 0.03 mg/kg produced grade II drowsiness and fatigue in 1 of 2 men who reached that dose, which is why 0.025 mg/kg was the dose carried forward [1].
0.5 mg (500 mcg)
2-3 times per week · Ongoing maintenance
Community-reported maintenance schedule, not peer-reviewed. No published trial tested a maintenance phase; the longest published human dosing was 10 subcutaneous doses over 2 weeks in 3 healthy men [1]. A systemic-toxicity case followed a 6 mg self-injection, roughly three times the 0.025 mg/kg dose used in trials [9].
PT-141 (Bremelanotide)
Subcutaneous
1 mg
As needed, ~45 min before sexual activity; no more than once per 24 h · Trial period (assess response/tolerability)
Lower 1 mg trial dose used in practice to gauge nausea tolerance before moving to the FDA dose [6]. Inject into abdomen or thigh.
1.75 mg
As needed, ~45 min before sexual activity; max once per 24 h and 8 doses per 28 days · Ongoing as needed
FDA-approved Vyleesi dose for hypoactive sexual desire disorder in premenopausal women; efficacy shown in the RECONNECT phase 3 trials [1][6].
Best suited for
Melanotan-2
Fair-Skinned Individuals Who Struggle to Tan
If you're the type who burns before you bronze, MT-2 can be a game-changer. It works by telling your skin cells to produce more melanin—the pigment that creates a tan. [13][17] People who normally can't tan often see the most dramatic results.
Those Wanting to Reduce Sun Exposure
MT-2 means you need far less UV exposure to develop and maintain a tan. A few minutes of sun or a brief tanning bed session goes much further. This could potentially reduce your cumulative UV damage over time.
Year-Round Tan Maintenance
Unlike a natural tan that fades quickly, MT-2 tans last longer and can be maintained year-round with minimal upkeep. Many users find they can keep their summer color through winter with just weekly maintenance doses.
Those Experiencing Low Libido
MT-2 has significant effects on sexual arousal and function in both men and women. [18][13] While PT-141 is more targeted for this purpose, [10] some users appreciate getting tanning and libido benefits from one peptide.
PT-141 (Bremelanotide)
Women with Low Sexual Desire (HSDD)
PT-141 is FDA-approved specifically for premenopausal women with acquired, generalized hypoactive sexual desire disorder—when you used to have normal desire but it's faded, and it's causing real distress in your life. It's the only approved treatment that works through brain pathways rather than hormones.
Men Who Don't Respond to Viagra-Type Medications
While not FDA-approved for men, clinical research shows PT-141 may help men with erectile dysfunction who don't respond to PDE5 inhibitors like Viagra or Cialis. Because it works through the brain rather than blood vessels, it offers a completely different approach.
Those Wanting On-Demand Treatment
Unlike daily medications like flibanserin (Addyi), PT-141 is used only when you want it—take it 45 minutes before intimacy. This gives you control over timing without committing to daily pills.
People Seeking to Address the 'Wanting' Part of Intimacy
Many sexual health treatments focus on the physical mechanics (blood flow, lubrication). PT-141 is unique because it targets desire itself—the psychological 'wanting' that initiates intimacy. It works on your brain's arousal circuits.
Side effects
Melanotan-2
Common
- Facial flushing
- Nausea
- Darkening of moles and freckles
- Spontaneous erections (men)
- Drowsiness and fatigue
Uncommon
- New mole formation
- Headaches
Serious
- Priapism (prolonged erection)
- Concerning mole changes
PT-141 (Bremelanotide)
Common
- Nausea
- Facial flushing
- Headache
- Injection site reactions
Uncommon
- Skin darkening (hyperpigmentation)
Serious
- Blood pressure increase
Safety & evidence
Melanotan-2
Evidence level
Limited human trials
FDA status
Not FDA approved
Safety overview
Human safety data for melanotan-2 comes from small trials totalling about 23 men, plus a handful of published case reports. In the phase-I study of 3 healthy men, mild nausea was reported at most dose levels, and the 0.03 mg/kg dose caused grade II drowsiness and fatigue in 1 of the 2 men who reached it — which is why 0.025 mg/kg was the dose carried forward [1]. Across 20 men with erectile dysfunction given 0.025 mg/kg, severe nausea occurred in about 1 in 8 (12.9%) [4]. In the psychogenic erectile-dysfunction trial, nausea, stretching and yawning, and reduced appetite were each more common on melanotan-2 than on placebo, though none required treatment [6]. Beyond the trials, single case reports describe rhabdomyolysis (muscle breakdown that can injure the kidneys) after a 6 mg injection [9], ischaemic priapism needing surgery [10], melanoma in a 20-year-old woman who used it alongside sunbeds [8], and mucosal melanoma in a 22-year-old woman who used a nasal spray version [11]. A case report shows that something happened in one person; it cannot show how often it happens.
Contraindications
- History of melanoma or skin cancer
- Family history of melanoma
- Large number of atypical moles
- Pregnancy or breastfeeding
- Severe cardiovascular disease
PT-141 (Bremelanotide)
Evidence level
Strong human trials (Phase 3 or FDA approved)
FDA status
FDA approved for this use
Safety overview
PT-141 has undergone rigorous FDA review and was approved in 2019 based on two large Phase 3 clinical trials involving over 1,200 women. The most common side effect is nausea (affecting about 40% of users), which typically decreases with repeated use. The drug causes transient increases in blood pressure (average 2-3 mmHg) and slight decreases in heart rate, which is why it's contraindicated in uncontrolled hypertension. Long-term safety data from the 52-week extension study showed no new safety concerns.
Contraindications
- Uncontrolled high blood pressure
- Cardiovascular disease
- History of heart attack or stroke
- Pregnancy or planning pregnancy
- Currently breastfeeding
Which is right for you?
Choose Melanotan-2 if...
- Achieving a natural-looking tan
- Reducing sun exposure time
- Enhancing libido and sexual function
- Appetite suppression
Choose PT-141 (Bremelanotide) if...
- Restoring sexual desire
- Treating hypoactive sexual desire disorder (HSDD)
- Enhancing arousal response
- Supporting intimacy when desire is low