Caffeine penetrates skin effectively and works through multiple pathways: it breaks down fat cells (relevant for anti-cellulite claims), acts as an antioxidant against UV damage, and increases blood flow to skin. Most commercial products contain 3% caffeine, though the study doesn't clarify whether this concentration actually delivers the claimed benefits in real-world use.

This is a review article that examined existing research on caffeine's mechanisms in skin, including lab studies using Franz diffusion cells to measure how caffeine penetrates skin barriers.

Funding not disclosed in abstract