I disagree; if you don't make any medical claims related to melatonin, and the final product doesn't produce any physiological effects due to melatonin, the product can't reasonably be called a medicine just because it contains melatonin
and unlike in the USA, suncreens are not classified as medicines or borderline medicines in Europe
to my mind, the biggest point of contention in using melatonin will be finding enough toxicology data to prove that it's safe for use in leave-on skin products
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