What is Melanotan 2? How does it work?

Melanotan 2, commonly shortened to MT2, is a synthetic peptide associated with increased skin pigmentation. This guide explains what Melanotan 2 is, what limited human research has reported, how it differs from afamelanotide, and why its effects, testing and UK regulatory position need to be described carefully.

For a broader overview of the terminology, reported effects and current UK regulatory position, read our guide to tanning injections in the UK.

What Is Melanotan 2?

Melanotan 2 is a synthetic cyclic peptide developed as an analogue of alpha-melanocyte-stimulating hormone, commonly abbreviated to α-MSH. This naturally occurring signalling hormone is involved in several processes within the body, including the regulation of melanin production. Melanotan 2 is also referred to as Melanotan II or MT-II in scientific literature. It interacts with the melanocortin-receptor system and has been studied for its effects on pigmentation and sexual arousal. Melanotan 2 is not authorised in the United Kingdom as a medicine for cosmetic tanning. Its regulatory treatment depends on the product format and how the product is presented. This distinction is explained in more detail later in this guide.

How Is Melanotan 2 Connected to Pigmentation?

Melanocytes are the cells responsible for producing melanin, the pigment that contributes to the colour of the skin, hair and eyes. The melanocortin 1 receptor, known as MC1R, forms part of the signalling pathway involved in this process. Melanotan 2 can interact with melanocortin receptors, including the receptor associated with melanin production. Increased activity within this pathway can result in greater pigmentation, although the extent and appearance of any change may vary considerably. Natural skin tone, genetics, freckles, moles, existing areas of pigmentation and exposure to ultraviolet radiation can all influence what is observed. Because Melanotan 2 is not selective only for the pigment-related receptor, effects unrelated to skin colour have also been reported.

What Has Human Research Found?

The human tanning evidence most frequently cited for Melanotan 2 comes from a small pilot phase I study published in 1996. The study involved three healthy male volunteers. Following administration under controlled study conditions, increased pigmentation was measured in two participants. The researchers also recorded nausea, flushing, fatigue, stretching and yawning, and spontaneous erections.^[1] This research provides early evidence that Melanotan 2 can affect human pigmentation. However, a study involving only three participants cannot establish long-term safety, show how frequently adverse effects occur or represent the wider population. It should therefore be understood as limited, early-stage evidence rather than proof that Melanotan 2 is safe or suitable for general human use.

What Are Tanning Injections and Nasal Tanning Sprays?

“Tanning injections” is an informal term commonly used for injectable products labelled as containing Melanotan, particularly Melanotan II. “Nasal tanning spray” is similarly used for products presented as delivering a Melanotan compound through a nasal spray. These terms describe product formats and how they are marketed. They are not the names of authorised cosmetic-tanning medicines. Products obtained through unregulated supply chains may differ in identity, measured content, purity, sterility, storage history and manufacturing conditions. The MHRA has warned that the contents of unauthorised products may be unknown and that they have not been shown to meet its standards for quality, safety and effectiveness.^[2]

Are Melanotan I and Melanotan II the Same?

No. Melanotan I and Melanotan II should not be treated as interchangeable names for the same compound. Melanotan II is a shorter, cyclic peptide that acts across multiple melanocortin receptors. It is commonly called Melanotan 2, Melanotan II, MT2 or MT-II. The name Melanotan I is often associated with afamelanotide. Afamelanotide is a different compound supplied as a controlled-release implant under the brand name Scenesse. It is authorised for a specific rare light-sensitivity condition called erythropoietic protoporphyria and is administered under specialist medical supervision.^[3] The authorisation of afamelanotide for that specific medical condition does not mean that Melanotan 2 is clinically equivalent, licensed or approved for cosmetic tanning.

What Effects Have Been Reported?

Effects described in early human research and subsequent medical literature include:

• Nausea
• Facial flushing
• Fatigue or tiredness
• Stretching and yawning
• Changes in appetite
• Spontaneous erections or changes in sexual arousal
• Darkening of freckles, moles and existing pigmentation

More serious events have also appeared in individual medical case reports. These include systemic toxicity accompanied by rhabdomyolysis and kidney dysfunction, as well as prolonged painful erections requiring urgent treatment.^[4][5] A case report describes what happened to one patient or a small number of patients. It can identify a possible safety signal, but it cannot show how frequently an event occurs or prove by itself that Melanotan 2 was the sole cause. Reported associations should therefore be described accurately. They should not be presented as universal outcomes, but they should not be dismissed simply because the available evidence is limited. Our separate guide examines the possible side effects of Melanotan 2 in greater detail.

What About Moles and Pigmentation Changes?

Darkening of existing moles and the appearance of new or more noticeable areas of pigmentation have been reported following Melanotan II use. One published case report described eruptive naevi and darkening of existing naevi shortly after administration.^[6] Reports of this kind do not establish that Melanotan 2 causes melanoma. They also do not allow researchers to calculate the level of risk. UV exposure, family history, natural skin type and other existing risk factors may all be relevant. Nevertheless, changes involving moles should be taken seriously. NHS guidance recommends seeking medical advice about a new mole, growth or lump, or a mole, freckle or patch of skin that changes in size, shape or colour.^[7]

Are the Effects of Melanotan 2 Permanent?

There is not enough reliable human evidence to provide a universal timeline for how long pigmentation or other reported effects will last. General skin pigmentation may reduce as skin cells naturally renew, but the rate and extent of any change can differ between individuals. Freckles, moles and areas of hyperpigmentation may behave differently from a general change in skin tone. Claims that every effect will disappear within a guaranteed number of weeks or months are not supported by strong clinical evidence. Our separate guide discusses whether effects associated with Melanotan 2 are reversible.

Does Melanotan 2 Protect Against UV Damage?

No tan should be treated as adequate protection against ultraviolet radiation. A darker appearance does not make skin immune to sunburn, DNA damage, premature skin ageing or skin cancer. The NHS states that there is no safe or healthy way to obtain a UV tan and that a tan does not protect the skin from the harmful effects of the sun.^[8] Current NHS sun-safety advice includes:

• Spending time in the shade when sunlight is strongest
• Covering the skin with suitable clothing
• Avoiding sunburn
• Using sunscreen with an SPF of at least 30
• Choosing sunscreen with at least four-star UVA protection
• Reapplying sunscreen regularly and after swimming or sweating

These precautions remain relevant regardless of natural skin tone or visible pigmentation.

What Can Independent Laboratory Testing Show?

Laboratory testing can provide useful information about the particular sample submitted for analysis. Depending on the methods used, a report may record:

• The reported identity of the submitted substance
• Measured content
• Reported purity
• The analytical method used
• The testing date
• The laboratory responsible for the analysis
• A sample, order or batch identifier

The laboratory document currently published by Pure MT2 records a sample identified by laboratory order number 100011931. The report identifies the submitted sample as Melanotan II, records measured content of 9.97mg and reports purity of 99%. The analysis was completed in January 2026. Those findings relate only to the submitted sample identified in that document. The report does not establish:

• Clinical safety or effectiveness
• Sterility or suitability for human use
• Nasal absorption or delivery
• Regulatory approval
• The composition of another vial, lot or future batch

Laboratory analysis should therefore be described precisely. It can support specific identity, measured-content and purity statements about the tested sample, but it does not make a product an authorised medicine or demonstrate that it is safe for human use. View the complete Pure MT2 laboratory report and chromatogram.

What Is the UK Regulatory Position?

The UK regulatory position is more specific than a simple statement that every Melanotan 2 product is treated in exactly the same way. In a December 2025 parliamentary answer, the Department of Health and Social Care stated that Melanotan II injections and pens are considered medicinal products. Medicinal products require the relevant marketing authorisation to be legally sold and supplied in the United Kingdom.^[9] The same answer stated that tan-enhancing nasal products marketed clearly for cosmetic self-tanning, without a medical purpose, do not fall within medicines regulations or the MHRA’s remit.^[9] Regulatory classification can therefore depend on the product format, its presentation and the claims used to market it. A disclaimer should not be treated as a substitute for specialist regulatory or legal advice.

When Should Someone Seek Medical Advice?

Anyone experiencing concerning, severe or persistent symptoms should contact a qualified healthcare professional. NHS 111 can provide advice when someone is worried about their health but does not require immediate emergency assistance. Urgent medical help should be sought for symptoms such as difficulty breathing, collapse, chest pain, severe confusion or a prolonged and painful erection. Any new or changing mole, unusual growth or changing patch of pigmentation should also be assessed by a healthcare professional. Suspected adverse reactions involving a medicine or unauthorised product can be reported through the MHRA Yellow Card scheme.^[10]

Summary

Melanotan 2 is a synthetic melanocortin peptide associated with increased skin pigmentation. Early human evidence exists, but the study most often cited for pigmentation involved only three participants and does not establish long-term safety. Reported effects range from nausea, flushing and pigmentation changes to more serious events described in individual case reports. These reports can identify possible safety signals but cannot establish how commonly an event occurs or prove causation in every case. A darker appearance should not be confused with protection from ultraviolet radiation. Independent laboratory testing can provide useful information about the particular sample analysed, but it cannot demonstrate clinical safety, effectiveness, sterility or regulatory approval. In the United Kingdom, Melanotan II injections and pens are treated as medicinal products. Cosmetic tan-enhancing nasal products presented without a medical purpose are treated differently under the current position described by the Department of Health and Social Care.

Sources and Further Reading

1. Dorr RT, Lines R, Levine N, et al. Evaluation of Melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study. Life Sciences. 1996;58(20):1777-1784.
2. Medicines and Healthcare products Regulatory Agency. Side effects reports of Melanotan II products, FOI 24/274. 17 April 2024.
3. European Medicines Agency. Scenesse: European public assessment information.
4. Nelson ME, Bryant SM, Aks SE. Melanotan II injection resulting in systemic toxicity and rhabdomyolysis. Clinical Toxicology. 2012;50(10):1169-1173.
5. Mallory CW, Lopategui DM, Cordon BH. Melanotan tanning injection: a rare cause of priapism. Sexual Medicine. 2021;9(2):100298.
6. Schulze F, Erdmann H, Hardkop LH, et al. Eruptive naevi and darkening of pre-existing naevi 24 hours after a single injection of Melanotan II. European Journal of Dermatology. 2014;24(1):107-109.
7. NHS. Melanoma skin cancer.
8. NHS. Sunscreen and sun safety.
9. UK Parliament, Department of Health and Social Care. Legal status of products containing Melanotan II. Answered 15 December 2025.
10. Medicines and Healthcare products Regulatory Agency. Yellow Card reporting scheme.

Last evidence review: 22 September 2026