Melanotan II

Key points

• Melanotan II is a synthetic melanocortin peptide, first explored decades ago as a possible tanning agent.
• It acts on several melanocortin receptors at once, which is why its effects, on skin colour, appetite and arousal, are broad and hard to predict.
• It has never been approved as a medicine, and the MHRA has warned the public against using it.
• Human evidence is very limited, and there are reports of serious harms.

Quick facts

What it is

Synthetic melanocortin peptide (cyclic, 7 amino acids)

Marketed for

Skin tanning; sometimes appetite or erections

UK status

Never approved; MHRA has warned against use

Human evidence

Very limited; one small early study

How it works

Melanotan II activates a family of melanocortin receptors. One of them increases the skin pigment melanin, which is the tanning effect. Others, in the brain, influence appetite and sexual arousal, which explains the other reported effects. Because it is not selective, it switches on several systems at once, and the results vary from person to person. The more targeted peptide bremelanotide (PT-141) was later developed from the same research.

What the evidence shows

Human testing barely got started. The main early study involved just three volunteers and a single dose, and it is backed only by animal and laboratory work. There is no body of controlled human evidence for safety or benefit, which is a large part of why it was never approved.

What it does not settle

• There is almost no human safety or efficacy data.
• Effects in women, and any long term risks, are essentially unstudied.
• The effect on moles and skin cancer risk has not been established.

Side effects

Common

• Nausea soon after injecting, flushing, tiredness and yawning, and general darkening of the skin rather than an even tan.
• Spontaneous erections and reduced appetite are also reported.

Less common but serious

• Existing moles can darken or grow. Any change in a mole should be checked promptly, since the effect on skin cancer risk is not known.
• Rare but serious harms have been reported, including kidney problems, muscle breakdown and prolonged painful erections. Seek urgent care for flank pain, blood in the urine, severe muscle pain, or an erection lasting more than four hours.

Report any suspected side effect through the MHRA Yellow Card scheme.

UK legal status and access

Melanotan II has never been approved as a medicine, so it is not available through registered clinics or pharmacies. It is sold online as a research chemical, with no checks on quality or sterility. The MHRA has warned against buying or using it.

Common questions