The clinical and histological effect of home-use, combination blue-red LED phototherapy for mild-to-moderate acne vulgaris in Korean patients: a double-blind, randomized controlled trial

Summary Background Blue and red light have been reported to have beneficial effects on acne. However, there has been no double‐blind, randomized study of acne treatment for combined blue and red light‐emitting diode (LED) devices, and the associated molecular mechanisms have rarely been investigated. Objectives To evaluate the efficacy, safety and histological changes of combined blue and red LED phototherapy for acne vulgaris. Methods Thirty‐five patients with mild‐to‐moderate acne were randomly assigned to either a home‐use irradiation group using an LED device, or a control group using a sham device. The treatment group was instructed to serially irradiate their forehead and cheeks with 420‐nm blue light and 660‐nm red light for 2·5 min twice daily for 4 weeks. Results At the final visit at 12 weeks, both inflammatory and noninflammatory acne lesions had decreased significantly, by 77% and 54%, respectively, in the treatment group. No significant difference was observed in the control group. In the treatment group, sebum output reduction, attenuated inflammatory cell infiltrations and a decreased size of the sebaceous gland were found. The immunostaining intensities for interleukin (IL)‐8, IL‐1α, matrix metalloproteinase‐9, toll‐like receptor‐2, nuclear factor‐κB, insulin‐like growth factor‐1 receptor and sterol response element binding protein (SREBP)‐1 were reduced concomitantly. Messenger RNA expression of SREBP‐1c was also decreased. No severe adverse reactions were reported. Conclusions This LED phototherapy was safe and effective for treating not only inflammatory but also noninflammatory acne lesions, with good compliance. The experimental results correlated well with clinical results, partly elucidating the related molecular mechanisms. What’s already known about this topic? • Standard acne treatments have demonstrated modest efficacy, but they may cause various side‐effects and discomforts. • It has been reported that the beneficial effects of blue and red light on acne result from different, distinct mechanisms. However, there has been no double‐blind, randomized study for phototherapy with a combination of blue and red light‐emitting diodes (LEDs). • Previous clinical research has rarely elucidated the molecular interactions between visible light and active acne lesions. What does this study add? • A 12‐week, double‐blind, randomized sham‐device‐controlled study demonstrated that home‐use combination phototherapy with blue and red LE