Free radical

Free radicals are atoms or molecules that carry one or more unpaired electrons, making them highly reactive. They stabilise themselves by stealing electrons from nearby molecules — lipids in cell membranes, collagen fibres, or DNA — triggering chain reactions of oxidative damage. In skin, the primary sources of free radicals are UV radiation (generating reactive oxygen species) and environmental pollutants. Cumulative free-radical damage is a major driver of photoaging: collagen breakdown, loss of elasticity, and hyperpigmentation. Antioxidants in skincare interrupt this chain by donating electrons without becoming damaging radicals themselves.

• Antioxidant A molecule that neutralises free radicals by donating an electron, preventing oxidative damage to skin cells.