At a glance: Melanotan II is a lab-made hormone analog developed in the 1980s as a sunless tanning agent. It is sold online as injections and nasal sprays, sometimes called the "Barbie drug." It is not approved anywhere for human use, the FDA does not consider it a legal ingredient, and health agencies in several countries have warned against it since 2007. Reported risks include mole changes, painful prolonged erections, and rare kidney and muscle damage.
What is Melanotan II?
Melanotan II (MT-II) is a synthetic, ring-shaped (cyclic) version of alpha-melanocyte-stimulating hormone (alpha-MSH), the natural hormone that triggers skin pigment. It was created at the University of Arizona in the 1980s alongside Melanotan I, as part of research into tanning without sun exposure.
Melanotan II was licensed to Palatin Technologies, which dropped it in 2000 and instead developed a closely related compound, bremelanotide, now FDA-approved as Vyleesi for low sexual desire in women. Melanotan I went on to become afamelanotide (Scenesse), an approved medicine for a rare light-sensitivity disorder. Melanotan II itself was never developed into a medicine.
How does Melanotan II work?
Unlike Melanotan I, Melanotan II is non-selective: it activates several melanocortin receptors at once, which explains its wide range of effects:
- MC1R (skin): stimulates pigment cells to make melanin, darkening skin without sun
- MC4R and possibly MC3R (brain): trigger sexual arousal and spontaneous erections
- Appetite centers: reduce hunger, which some users seek for weight loss
- Other effects: nausea, flushing, yawning and stretching are common reactions
What the research shows so far
| Type of study | What was found | Strength of evidence |
|---|---|---|
| Early University of Arizona human studies (1990s) | Small studies found it darkened skin and triggered erections, including in men with erectile dysfunction, with nausea and flushing common | Small early trials; never developed further |
| Case reports | Melanoma, rapidly changing or new moles, kidney infarction (loss of blood supply), rhabdomyolysis (muscle breakdown) with kidney failure, and priapism | Individual reports; cause not always proven |
| Melanoma risk reviews (2013, 2021) | No conclusive evidence it directly causes melanoma; increased risk among users is linked to heavier sun and sunbed exposure | Reviews of limited data |
| Large controlled trials | None | None |
Most of what is known about Melanotan II's risks comes from case reports in people using unregulated products.
Why it gets attention
- Sunless tanning, marketed on social media as the "Barbie drug" or "tan jab"
- Nasal sprays sold online and in some salons and gyms
- Libido and erectile effects, which led to the development of bremelanotide
- Appetite suppression, which some users exploit for weight loss
How it is used
Melanotan II is sold online as powder for injection under the skin and as nasal sprays. These products are unregulated, untested for accurate labeling or sterility, and there is no established safe dose. A tan from Melanotan II does not replace sunscreen. This page does not provide dosing guidance.
What about side effects?
Commonly reported side effects:
- Skin changes: uneven darkening, new moles, or existing moles that grow or darken, and dark lines in the nails
- Flushing, nausea, vomiting, headache and reduced appetite
- Spontaneous and prolonged erections
Serious risks reported:
- Melanoma: cases have been reported in users, mostly alongside other risk factors such as fair skin, heavy sun or sunbed use, or family history. Darkened moles can also make melanoma harder to spot.
- Priapism: an erection lasting over four hours is a medical emergency that can cause permanent damage.
- Kidney damage: case reports describe kidney infarction and kidney failure linked to muscle breakdown (rhabdomyolysis).
- Allergic reactions, and infection from non-sterile products
It should not be used by anyone with a history of skin cancer, and its safety in pregnancy and breastfeeding is unknown.
Regulatory status
- Not approved for human use in any country. The FDA has not reviewed it for any use and does not consider it a legal dietary supplement or cosmetic ingredient.
- Warnings since 2007 from health agencies in multiple countries, including Australia's TGA, which has warned against tanning products containing melanotan, and UK trading standards, which linked nasal tanning sprays to skin cancer and breathing problems.
- Products are nevertheless sold online and in some gyms and salons, with no quality control.
Melanotan II vs related compounds
| Melanotan II | Melanotan I (afamelanotide) | Bremelanotide (Vyleesi) | |
|---|---|---|---|
| Receptors | Several (skin, brain, appetite) | Mainly pigment (MC1R) | Several, used for sexual desire |
| Main use | Unapproved tanning, libido | Approved implant for EPP | Approved for low sexual desire in women |
| Human evidence | Small early studies, case reports | Phase 3 trials | Phase 3 trials |
| US status | Not approved; not a legal ingredient | FDA-approved (2019) | FDA-approved (2019) |
The bottom line
Melanotan II is a powerful, non-selective hormone analog that was abandoned as a drug candidate, while two relatives became approved medicines. Today it circulates only as an unregulated tanning and libido product, with no controlled safety data and case reports of serious harm. Tanning safely means sunscreen and sunless lotions, not injections. Anyone with new or changing moles should see a dermatologist.
Frequently asked questions
What is Melanotan II?
A shorter synthetic analog of alpha-MSH that acts on several melanocortin receptors. Bremelanotide (PT-141) was developed from it.
How is Melanotan II taken?
Injection; not a licensed medicine.
Is Melanotan II FDA approved?
Not approved.
That means no regulator has reviewed its safety, effectiveness or manufacturing quality for this use.
What has research shown about Melanotan II?
- Skin tanning and erectile function in small human studies in the 1990s.
- Case reports of changes in moles and other side effects.
What side effects have been reported?
- Nausea
- Flushing
- Spontaneous erections in men
- Darkening of skin
Serious or less common risks are listed in the Side Effects section above.
What is still unknown about its safety?
Most of it. Melanotan II has not been through the trials that establish long-term safety in people, and products sold online are made by unregulated labs. Independent testing of online peptides has repeatedly found contents that do not match the label.
References
- WebMD: Melanotan, overview, uses, side effects and precautions. View source
- Peters B, et al. Melanotan II: a possible cause of renal infarction: review of the literature and case report. CEN Case Reports. 2020. View source
- Bohm M, et al. An overview of benefits and risks of chronic melanocortin-1 receptor activation (melanotan II melanoma cases). JEADV. 2025. View source
- Wikipedia: Melanotan II (history, receptor activity, melanoma reviews, regulatory warnings). View source