Caffeine

An antioxidant that can help reduce puffiness and improve skin's appearance. Caffeine acts primarily as a non-selective adenosine receptor antagonist, blocking adenosine's vasodilatory effects and leading to localized vasoconstriction, which helps reduce redness and puffiness (e.g., under-eye bags). It also inhibits phosphodiesterase, increasing intracellular cyclic AMP (cAMP) levels in adipocytes, thereby activating hormone-sensitive lipase to promote lipolysis and reduce fat cell size, relevant for anti-cellulite applications. Additionally, caffeine is a potent antioxidant, scavenging free radicals to protect skin from oxidative stress.

The Cosmetic Ingredient Review (CIR) Expert Panel concluded that Caffeine is safe as a cosmetic ingredient in the current practices of use and concentration. It is generally well-tolerated topically, with low irritation or sensitization potential, though some sensitive individuals may experience mild irritation at higher concentrations.

Look for products with 0.5-10% (most formulas, especially eye creams, use 0.5-5%; anti-cellulite products may use higher concentrations up to 10%). for clinical efficacy.