Phototherapy remains an essential dermatological treatment. Ultraviolet (280–400 nm) therapy is of significant significance; but, there remain concerns on its long-term use, as it can lead to skin ageing and carcinogenesis. A review described the role and the mechanism of action of blue light (400–500 nm), a UV-free method. 

Nitric oxide (NO) and reactive oxygen species (ROS) are the main mediators of cellular responses to blue light. However, its detailed mechanism is yet not clear. Light parameters are the main factors responsible for biological changes induced by blue light. It has been shown that blue light generates an anti-inflammatory and antiproliferative effect; making it advantageous for hyperproliferative and chronic inflammatory skin diseases like atopic dermatitis, eczema, and psoriasis. 

Blue light has also shown a reduction in itching and may be beneficial to hair growth. It can be utilized for treating acne vulgaris by reducing follicular colonization of Propionibacterium acnes. 

While there are studies that elaborate the negative effects of blue light like increased oxidative stress, reduced antioxidative capacity of fibroblasts, desynchronization of the cells’ nighttime rhythm, and increased inflammatory response, making it a hot topic of debate. Yet this method seems to be safe and the only observed clinical adverse effect may be transient hyperpigmentation. 

Further studies are warranted to develop accurate protocols since the clinical effects depend on the light parameters and the treatment length. The duration of the treatment, the dose as well as the intensity of irradiations all should be taken into account. No major adverse effects are reported yet, but long-term safety needs to be monitored as there is a lack of studies considering the long-term effects of blue light on the skin.

Source- Sadowska M, Narbutt J, Lesiak A. Blue Light in Dermatology, Life 2021, 11(7), 670; https://doi.org/10.3390/life11070670