A study gave a synthetic hormone called melanotan‑I (0.16 mg per kg body weight, injected under the skin in three 10‑day rounds over three months) to fair‑skinned volunteers. It made their skin much darker, especially in people who started with very little melanin, and cut sunburn cell damage by more than half and DNA damage by about 60%. This suggests melanotan‑I can boost natural tanning and give real UV protection, but it’s still an experimental approach.

Epidermal melanin reduces some effects of UV radiation, the major cause of skin cancer. To examine whether induced melanin can provide protection from sunburn injury, 65 subjects completed a trial with the potent synthetic melanotropin, [Nle4-D-Phe7]-alpha-melanocyte-stimulating hormone ([Nle4-D-Phe7]-alpha-MSH) delivered by subcutaneous injection into the abdomen at 0.16 mg/kg for three 10-day cycles over 3 months. Melanin density, measured by reflectance spectroscopy, increased significantly in all [Nle4-D-Phe7]-alpha-MSH-treated subjects. The highest increases were in volunteers with lowest baseline skin melanin levels. In subjects with low minimal erythemal dose (MED) skin type, melanin increased by an average of 41% (from 2.55 to 3.59, P < 0.0001 vs placebo) over eight separate skin sites compared with only 12% (from 4.18 to 4.70, P < 0.0001 vs placebo) in subjects with a high-MED skin type. Epidermal sunburn cells resulting from exposure to 3 MED of UV radiation were reduced by more than 50% after [Nle4-D-Phe7]-alpha-MSH treatment in the volunteers with low baseline MED. Thymine dimer formation was also shown to be reduced by 59% (P = 0.002) in the epidermal basal layer. This study has shown for the first time the potential ability of a synthetic hormone that augments melanin production to provide photoprotection to people who normally burn in direct sunlight.