Melanotan I (MT-1) common uses, half-life, side effects and more

Melanotan I is a synthetic copy of the hormone that tells skin to make pigment. The same molecule is an approved drug called afamelanotide. That approved product is a slow-release implant placed under the skin by a doctor to treat a rare disease that makes sunlight painful. The approval does not cover tanning. People buy Melanotan I as an unapproved powder and inject it to darken their skin without sun exposure. The implant and the powder are the same chemical in very different products so the safety record of one does not transfer to the other.

• Skin darkening without sun exposure
• Photoprotection in a rare light-sensitivity disease (the approved use)
• Reduced sunburn in very fair skin
• Bought as a milder alternative to Melanotan II

Every two months for the approved implant

The approved product is one 16 mg implant placed under the skin by a trained clinician every two months. No verified dose exists for the powder people inject. The early trials that produced tanning used about 0.16 mg per kg a day. That comes to roughly 11 to 13 mg a day for an average adult. The figures of 0.5 to 2 mg that circulate online trace only to uncited seller pages. Dosing past the point where the pigment receptor saturates adds side effects rather than color. No published analysis has ever measured what a gray-market Melanotan I vial actually contains.

The approved implant shows an apparent half-life of about 15 hours. That number belongs to the implant's slow release rather than to the peptide itself. Injected on its own the peptide clears with a half-life of roughly one to two hours. The implant releases most of its drug within five days and is undetectable by day ten. Pigment lasts far longer than the drug does. Tanning peaked about a week after a course ended and was still visible three weeks later. That is why one implant covers two months.

The approved implant is kept refrigerated and protected from light. No storage standard exists for the gray-market powder.

• Nausea and headache each affected about one in five people in trials
• Skin darkening and new moles were the two effects that clearly separated from placebo
• Facial flushing and nausea followed injected doses in an early trial
• Fatigue, dizziness, or drowsiness reported at low rates
• Implant-site reactions that belong to the implant rather than to an injection

Melanotan I switches on the pigment receptor on skin cells and drives the darker pigment without any sun exposure. It is a far more potent and longer-lasting version of the natural hormone. It is often called selective for that pigment receptor. That is wrong. It binds the appetite and arousal receptors too. The approved implant stays mild because it releases slowly and holds a low steady level that saturates the pigment receptor without reaching the others. An injection instead creates a brief high peak. An early trial of injected Melanotan I in healthy volunteers produced flushing and nausea. Once the pigment receptor is saturated more drug cannot make more pigment.

The evidence splits sharply by product. The approved implant has genuine randomized trial evidence in a rare light-sensitivity disease. Two trials in 168 patients found more pain-free time in sunlight. A later study of 117 patients found more time outdoors and less painful reactions. That same study found no drop in how often reactions happened. Cosmetic tanning has almost no evidence behind it. Early trials showed that injections do darken skin though the effect was significant at only three of eight body sites. No trial has tested the gray-market powder people inject for tanning. The approved safety record was generated with a supervised implant and does not describe self-injection.

• The approval covers a rare light-sensitivity disease rather than cosmetic tanning so the tested safety record does not cover what people inject
• It darkens existing moles and freckles and the approved label calls for a full-body skin check twice a year
• Combining it with sunbeds reintroduces the ultraviolet exposure the drug was meant to replace
• Serious allergic reactions including anaphylaxis have been reported and the approved product is barred in reduced liver or kidney function
• Melanoma cases and the muscle, kidney, and prolonged-erection injuries circulating online involve Melanotan II rather than Melanotan I
• Avoid it in pregnancy and breastfeeding since no data exist either way