The two faces of blue light: From treating inflammation to causing oxidative stress in the skin.

Blue light (400-500 nm) is becoming increasingly important in dermatology due to its multidirectional biological effects. Its varied anti-inflammatory, antimicrobial, antitumour and antiproliferative properties make it a promising therapeutic tool in the treatment of various skin conditions, such as acne vulgaris, psoriasis and atopic dermatitis. However, other reports indicate that it can also have harmful effects on the skin, such as hyperpigmentation, disruption of the dermal circadian rhythm, increased free radical production, degradation of carotenoids, DNA damage, activation of apoptotic pathways and accelerated skin ageing. The article presents substances known to protect against blue light exposure, or have a soothing effect, such as antioxidants and photo filters. The paper provides a comprehensive overview of the topic, with the aim of improving understanding of the therapeutic potential of blue light and the need for responsible use in clinical practice.