Ingredient

Adenosine

A naturally occurring compound found in all living cells that signals skin to rebuild collagen -- the protein responsible for firmness. In K-beauty, it is one of the only cosmetic ingredients formally approved by Korean health authorities to make wrinkle-reduction claims, which means the evidence standard is more rigorous than most. Effective from 0.04%; most products use 0.04-0.1%, with results typically visible after 4-8 weeks.