Published human research involving Melanotan 2 is far more limited than online discussions often suggest. The principal clinical evidence consists of one three-person Phase I pilot study and two small erectile-function studies involving ten men each.
This article examines what those studies actually reported, how many people participated and what the results cannot establish. It also explains why studies involving Melanotan 1, afamelanotide or bremelanotide should not be presented as direct clinical evidence for Melanotan 2.
How Much Human Research Exists?
The main published human evidence examined in this guide comes from three small studies involving 23 male participants in total:
- A Phase I pilot study involving three healthy male volunteers
- A placebo-controlled crossover study involving ten men with psychogenic erectile dysfunction
- A placebo-controlled crossover study involving ten men with organic erectile dysfunction
A later publication discussed results from 20 men with psychogenic or organic erectile dysfunction. This was a combined analysis of the same two ten-person study groups, not a separate trial involving 20 additional participants.
This means the available evidence should not be described as a large clinical-trial programme. The studies established that Melanotan 2 is biologically active in humans, but they were not designed to determine its long-term safety or its suitability for routine use.
The First Phase I Pilot Study
The first published human study was conducted by Dorr and colleagues and appeared in Life Sciences in 1996.[1]
It involved three healthy male volunteers. Melanotan 2 was administered by subcutaneous injection over a short experimental period, beginning at 0.01mg per kilogram and increasing to 0.025mg or 0.03mg per kilogram.
The study used five low active doses, administered on alternating days. Its purpose was to investigate biological activity, tolerability and pigmentation, not to establish a consumer dosing protocol.
What the Phase I Study Reported
Two of the three participants developed measurable increases in pigmentation involving areas including the face, upper body and buttocks. The findings demonstrated that Melanotan 2 could affect human pigmentation after limited exposure.
Reported effects also included:
- Mild nausea at several dose levels
- Somnolence and fatigue in one participant at the higher 0.03mg per kilogram dose
- Stretching and yawning
- Spontaneous penile erections
The erections were not the intended outcome of the pigmentation research. Their appearance helped direct later research towards the melanocortin system and sexual function.
What This Study Did Not Establish
The study showed biological activity, but its size and duration create substantial limitations.
Three participants are not enough to determine:
- How frequently particular effects occur in a wider population
- Whether responses differ between men and women
- Long-term safety
- The effect of repeated or prolonged exposure
- The incidence of serious adverse events
- Whether induced pigmentation reduces UV damage or skin-cancer risk
- Whether findings from a controlled research product apply to products sold online
The study should therefore be described as preliminary human evidence, not proof of general safety or effectiveness.
Study in Men With Psychogenic Erectile Dysfunction
In 1998, Wessells and colleagues published a double-blind, placebo-controlled crossover study involving ten men with erectile dysfunction that had no identified organic cause.[2]
In a crossover study, participants receive both the experimental intervention and placebo during different study sessions. Each participant can therefore act as his own comparison.
Penile rigidity was monitored objectively using RigiScan equipment. The study reported that eight of the ten participants developed clinically apparent erections following Melanotan 2.
The mean duration of tip rigidity above 80 percent was approximately:
- 38 minutes after Melanotan 2
- 3 minutes after placebo
These erections occurred without deliberate erotic stimulation during the observation period.
Reported Effects in the Psychogenic Study
Nausea, stretching, yawning and reduced appetite were reported more frequently after Melanotan 2 than after placebo.
The researchers described Melanotan 2 as a potent initiator of erections within this particular study population. However, that conclusion should not be extended into a claim that Melanotan 2 is an established treatment for erectile dysfunction.
The study included only ten men, measured short-term responses and did not establish long-term effectiveness or safety.
Study in Men With Organic Erectile Dysfunction
A second double-blind, placebo-controlled crossover study examined ten men with erectile dysfunction associated with organic risk factors.[3]
Across the crossover sessions, researchers administered 19 Melanotan 2 injections and 21 placebo injections. One participant underwent additional placebo sessions, which explains why the number of injections was greater than the number of participants.
Subjectively reported erections occurred following:
- 12 of 19 Melanotan 2 injections
- 1 of 21 placebo injections
The mean duration of tip rigidity above 80 percent was reported as approximately:
- 45.3 minutes after Melanotan 2
- 1.9 minutes after placebo
Reports of increased sexual desire were also more frequent following Melanotan 2 than following placebo.
Adverse Effects in the Organic Study
Nausea and stretching or yawning were again commonly reported. Severe nausea was recorded after four of the 19 Melanotan 2 injections.
This is important because the study demonstrated both biological activity and a meaningful tolerability problem. The results cannot accurately be presented as evidence of benefit without also reporting the adverse effects.
Anyone experiencing a painful erection or an erection lasting four hours or longer requires urgent medical assessment.
Was There a Separate 20-Person Trial?
A 2000 publication reported combined findings from 20 men with psychogenic or organic erectile dysfunction.[4]
It stated that erections occurred in 17 of the 20 participants following Melanotan 2, with an average of approximately 41 minutes of tip rigidity above 80 percent. Increased sexual desire was reported after 68 percent of active doses compared with 19 percent of placebo doses.
However, this publication reviewed the results from the two previously described ten-person study populations. It should not be counted as a separate trial involving another 20 men.
Presenting it as an additional clinical trial would artificially inflate the apparent size of the human evidence base.
What Did the Studies Show About Pigmentation?
The three-person Phase I pilot provides the clearest direct human evidence about Melanotan 2 and pigmentation. Two of its three participants developed measurable increases in pigmentation following the experimental dosing period.
The later erectile-function studies were designed primarily to measure erections, rigidity, sexual desire and short-term adverse effects. They should not be treated as large dermatological trials.
The evidence supports the conclusion that Melanotan 2 can influence human pigmentation. It does not establish that the resulting colour is:
- Even or cosmetically predictable
- Safe
- Permanent or temporary within a defined timeframe
- Equivalent to naturally darker skin
- Protective against sunburn, DNA damage or skin cancer
Learn more about the underlying pigmentation pathway in our guide explaining what Melanotan 2 is and how it works.
Did the Trials Prove That MT2 Protects Against UV Damage?
No. The early development rationale included investigating whether increased pigmentation might provide photoprotection. However, the published Melanotan 2 studies described here did not establish a reduction in sunburn, cellular DNA damage or skin-cancer incidence.
Increased pigmentation and proven protection against UV-related harm are not interchangeable outcomes.
The NHS states that a tan does not protect skin from the harmful effects of the sun and recommends shade, protective clothing and sunscreen with at least SPF 30 and suitable UVA protection.[5]
Melanotan 2 induced pigmentation should not be treated as a replacement for established sun-protection measures.
Were Mole Changes Observed in These Trials?
The current version of this article stated that freckling, darkening of existing moles and new pigmented lesions were observed during the early trials. That wording is too broad.
The small trials established pigmentation and several systemic effects, but concerns involving existing moles, new atypical moles and melanoma largely come from later case reports and reviews of unregulated melanocortin analogue use.[6]
Case reports can identify possible safety signals, but they cannot determine how common an event is or prove that Melanotan 2 caused every reported lesion.
A new mole or a mole, freckle or skin patch that changes in size, shape or colour should be assessed by a qualified healthcare professional. Further information is available in our guide to the possible side effects of Melanotan 2.
Melanotan 2 Is Not the Same as Melanotan 1
Research involving Melanotan 1 or afamelanotide should not be presented as though it involved Melanotan 2.
The names are similar, but the compounds are different. They have different structures, receptor profiles, development histories and regulatory positions.
Afamelanotide has undergone a much larger clinical-development programme for a specific medical indication. Evidence involving a licensed afamelanotide implant cannot be transferred automatically to unlicensed Melanotan 2 products.
Statements such as “Melanotan has been clinically approved” are misleading when used to describe Melanotan 2.
What About Bremelanotide or PT-141?
Bremelanotide, also known during development as PT-141, is related to Melanotan 2 but is not the same compound.
Its development was influenced by the sexual effects observed during Melanotan 2 research. However, later clinical trials involving bremelanotide are evidence for bremelanotide, not additional trials proving the safety or effectiveness of Melanotan 2.
Combining results from these related compounds would make the Melanotan 2 evidence base appear larger than it is.
What Was Not Studied?
The published studies leave many important questions unanswered.
They did not provide reliable long-term information about:
- Cardiovascular effects
- Liver or kidney safety
- Hormonal or reproductive effects
- Repeated long-term exposure
- Use during pregnancy or breastfeeding
- Effects in women
- Interactions with medicines or underlying health conditions
- Long-term changes to moles or pigmentation
- Skin-cancer incidence
- Nasal absorption or intranasal effectiveness
The injection studies also cannot be used to prove that an intranasal product delivers a comparable amount of Melanotan 2 into the body. Different administration routes require their own pharmacokinetic and clinical evidence.
Clinical Research Is Not the Same as User Experience
Online testimonials can describe what an individual believes happened after using a product, but they do not provide the controls found in clinical research.
A user report often cannot establish:
- The identity of the substance used
- Its measured content or purity
- Whether another factor caused the reported effect
- How frequently the experience occurs
- Whether the result would apply to another person
User experiences should therefore be labelled as anecdotal rather than being presented as clinical evidence.
Laboratory Analysis Is Not a Human Trial
Independent laboratory analysis can examine the identity, measured content and reported purity of the submitted sample. It does not establish clinical safety or effectiveness.
Pure MT2 publishes its available independent laboratory analysis. The current document reports that the submitted sample was identified as Melanotan II, with measured content of 9.97mg and reported purity of 99%.
Those findings apply to the sample identified by laboratory order number 100011931. The report does not establish:
- How the product affects a person
- Clinical safety or effectiveness
- Sterility or suitability for human use
- Absorption through the nose or another administration route
- Regulatory approval
- The composition of a different sample, lot or batch
Chemical analysis and clinical research answer different questions and should not be treated as interchangeable forms of evidence.
UK Regulatory Position
Melanotan 2 is not a licensed medicine in the United Kingdom.
The UK Government has previously stated that no Melanotan product holds UK marketing authorisation and that Melanotan products are subject to medicines regulation.[7]
The early experimental studies did not result in Melanotan 2 becoming an authorised treatment for tanning, UV protection or erectile dysfunction.
What Can We Conclude From the Human Studies?
The studies provide evidence that Melanotan 2 is biologically active in humans.
Within the small groups investigated, researchers observed:
- Increased skin pigmentation in two of three healthy volunteers
- Spontaneous erections in some male participants
- Increased reports of sexual desire in the organic erectile-dysfunction study
- Nausea
- Stretching and yawning
- Reduced appetite
- Fatigue or somnolence at a higher experimental dose
These findings show that Melanotan 2 can affect several melanocortin-related biological pathways. They do not establish that it is safe, suitable for general use or effective for a licensed medical purpose.
The most important limitation is scale. The controlled and pilot evidence discussed here involved only 23 men, with short treatment or observation periods and no adequate long-term follow-up.
The balanced conclusion is therefore that Melanotan 2 has demonstrated human biological effects, while its long-term safety, wider effectiveness and risk profile remain inadequately established.
Important Information
This article is provided for general educational purposes. It does not provide medical advice, recommend Melanotan 2 or supply instructions for administering it.
Anyone experiencing severe or persistent symptoms should seek medical advice. A painful erection or one lasting four hours or longer requires urgent medical assessment.
Sources and Further Reading
- Dorr RT, et al. Evaluation of Melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study. Life Sciences. 1996.
- Wessells H, et al. Synthetic melanotropic peptide initiates erections in men with psychogenic erectile dysfunction: double-blind, placebo-controlled crossover study. Journal of Urology. 1998.
- Wessells H, et al. Effect of an alpha-melanocyte stimulating hormone analog on penile erection and sexual desire in men with organic erectile dysfunction. Urology. 2000.
- Wessells H, et al. Melanocortin receptor agonists, penile erection, and sexual motivation: human studies with Melanotan II. International Journal of Impotence Research. 2000.
- NHS. Sunscreen and sun safety. Reviewed 24 March 2026.
- Habbema L, et al. Risks of unregulated use of alpha-melanocyte-stimulating hormone analogues: a review. International Journal of Dermatology. 2017.
- UK Parliament. Melanotan and UK regulatory controls. Answered 16 June 2014.
Last evidence review: 18 September 2026.