Blue/red light treatment

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 the likelihood of skin damage in the long term. 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 405-420 nm activates a porphyrin (Coproporphyrin III) in Propionibacterium acnes which damages and ultimately kills the bacteria by releasing singlet oxygen. A total of 320 J/cm² of light within this range renders the bacteria non viableBritish Journal of dermatology 2000 effectiveness of blue/red light treatments . 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 and the 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. The light at a dermatologist clinic is likely to be of a higher intensity, however, possibly negating the disadvantage of infrequent use. As of 2007 even though most light boxes are considered expensive, the cost is on a par with the total cost of benzoyl peroxide, moisturiser and facial washes over the total life of the light box.Fact: date=December 2007

Photodynamic therapy

Application in a dermatologist's office is usually much more costly, and not necessarily any more effective, but the visible blue light is sometimes used with off-label use of aminolevulinic acid; this causes the bacteria to generate more than normal quantities of porphyrins which greatly improves response. Whilst temporary redness and edema is experienced, this can give over a year of clearance with just a few applications.