Blue Light Phototherapy

Blue Light Phototherapy is a treatment for acne that uses high intensity blue light (~415 nm) to directly kill acne-causing Propionibacterium acnes bacteria that are growing in the skin.

P. acnes bacteria produce a molecule called Coproporphyrin III that produces free radicals when exposed to high intensity blue light. Blue Light Phototherapy works by causing Coproporphyrin III to produce enough free radicals to damage and kill P. acnes bacteria. P. acnes bacteria fluoresce when exposed to high intensity blue light, which can be observed with the help of special photographic filters (see attached image).

Multiple clinical research studies have reported that Blue Light Phototherapy can temporarily reduce the number of acne-causing P. acnes bacteria that are growing within hair follicles. This reduction can significantly improve acne symptoms in many patients. However, the effect of Blue Light Photherapy is temporary, so treatment must be repeated on a regular basis.
Blue Light Phototherapy is non-invasive and generally has few side effects. Blue Light Phototherapy complements many other types of acne treatments and can be a helpful component of a comprehensive acne treatment plan.

In some cases, the skin of patients is treated with a sensitizing agent prior to Blue Light Phototherapy. This sensitizing agent (eg. ALA or MAL) causes P. acnes bacteria to increase their production of Porphyrins, thus making them more sensitive to treatment. The combination of Blue Light Phototherapy and a sensitizing agent is called Photodynamic Therapy (PDT). In addition to acne, Photodynamic Therapy is also used to treat certain types of skin cancer.

Blue Light Phototherapy is primarily available in dermatology clinics that have a focus on acne. It may also be available at some spas and wellness centers. Blue Light Phototherapy systems can also be purchased for home use. The effects of Blue Light Phototherapy are temporary and achieving the maximum therapeutic benefit requires regular treatments.

There are many home use Blue Light systems available for purchase on the internet. However, it should be noted that almost all of the acne research studies that reported positive results were using high-intensity Blue Light Phototherapy systems. Many of the small, inexpensive Blue Light products that are sold on the internet are unlikely to produce enough of blue light (in the correct spectrum) to be effective for the treatment of acne. Most home use Blue Light Phototherapy systems use LEDs as the light source.


Light-emitting diode 415 nm in the treatment of inflammatory acne: An open-label, multicentric, pilot investigation. Tremblay, et al. 2006.
An open study to determine the efficacy of blue light in the treatment of mild to moderate acne. Morton, et al. 2005.
Clinical Efficacy of Self-applied Blue Light Therapy for Mild-to-Moderate Facial Acne. Gold, et al. 2009.
Phototherapy with blue (415 nm) and red (660 nm) light in the treatment of acne vulgaris. PAPAGEORGIOU, et al. 1999.
Blue and Red Light Combination LED Phototherapy for Acne Vulgaris in Patients with Skin Phototype IV. Lee, et al. 2006.
Laser and other light therapies for the treatment of acne vulgaris: systematic review. Hamilton, et al. 2008.
Blue light phototherapy in the treatment of acne. Tzung, et al. 2004.
Acne phototherapy with a high-intensity, enhanced, narrow-band, blue light source: an open study and in vitro investigation. Kawada, et al. 2002.
The effective treatment of acne vulgaris by a high-intensity, narrow band 405-420 nm light source. Elman, et al. 2003.
Eradication of Propionibacterium acnes by its endogenic porphyrins after illumination with high intensity blue light. Ashkenazi, et al. 2003.