As the most important and largest surface barrier, the skin provides a necessary protection to the organism from the external factors, including chemical, biological, and physical irritation, injury, and others. External environmental irritants or their metabolites are inherent oxidants and/or directly or indirectly drive the production of various reactive oxidants, reactive oxygen species (ROSs), owing to the redox imbalances. ROSs, the most common free oxygen radicals, participate in a series of physiological and pathological skin processes. Here, we discussed the role of oxidative events in injury, repair, photoaging, and cutaneous disease development. Intrinsic and extrinsic factors lead to the skin barrier damage, which leads to the disequilibrium in oxidant and antioxidant balance and induces excessive ROS production. The underlying mechanisms include DNA damage, MAPK/AP-1, NF-κB, and JAK/STAT-signaling pathways, apoptosis and autophagy, and autoimmune reaction of melanocytes and keratinocytes. The skin employs a number of antioxidant agents to protect the oxidative balance, such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), ascorbic acid, and tocopherols. The results presented here indicate that antioxidant treatments may be effective when applied in the therapy of cutaneous diseases where oxidative stress plays a prominent pathogenic role.
