Blue/Red light treatment for Acne Vulgaris

Sunlight was long known to improve acne, and this was thought to be due to antibacterial and other effects of the ultraviolet spectrum; which cannot be used as a treatment due to long-term skin damage. However, artificial UV didn't work as well as sunlight.

It was found that some of the visible violet light, present in sunlight, in the range 405-420nm activates a porphyrin (Coproporphyrin III) in Propionibacterium acnes which damages and ultimately kills the bacteria by releasing singlet oxygen. A total of 320J/cm^2 of light within this range renders the bacteria non viable . This part of the spectrum is just outside the ultraviolet and produces little if any tanning or sunburn.

Application of the light for 3 consecutive days has been shown to reduce the bacteria in the pores by 99.9%. Since there are few porphyrins naturally found in the skin, the treatment is believed safe except in patients with porphyria; although eye protection is necessary due to light sensitive chemicals in the retina. The light is usually created by fluorescent lamps, bright LEDs or dichroic filament bulbs.

Treatment is often accompanied with application of red light which has been shown to activate ATP in human skin cells (essentially a photobiomodulation effect), and seems to improve response rates.

Overall improvements of on average 76% for 80% of patients occurs over 3 months; most studies show that it performs better than Benzoyl peroxide but treatment is far better tolerated. However, approximately 10% of users see no improvement.

Home use light boxes usually work well, are effective for people with long-term acne, are likely to be cheaper than dermatologist office light treatments, and can be repeated over several years for negligible cost, as opposed to once weekly or fortnightly. As of 2007 even though they are not cheap, the cost is on a par with the total cost of benzoyl peroxide, moisturizer and facial washes over the total life of the light box, and the light boxes may yet get cheaper due to economies of scale.