AcneExposure to sunlight

The seasonality of visits to dermatology offices can be used to estimate the effect of sunlight on risk of acne vulgaris. Most studies of seasonality find higher rates of acne vulgaris in winter or spring, lower rates in summer.

In some countries, acne vulgaris is more common in winter: Saudi Arabia1 and Turkey2.

Acne is more common in spring in some countries: Nepal3.

In Sweden, “The majority of subjects with atopic eczema, acne vulgaris or seborrheic dermatitis experienced improvement after exposure to sunlight.”4.

In Germany, “About one-third of the patients reported an aggravation of their acne in winter, but also approximately one-third of the patients complained about an aggravation of their acne in summer. Another third did not notice any change.”5.

However, in India, aggravation was more pronounced in summer, likely due to high temperature and humidity leading to sweating6.

These findings support a role of sunshine in reducing the risk of acne vulgaris. UVB seems to have the ability to destroy bacteria7. However, the findings regarding season may not be necessarily due to solar UVB. Laser therapy using blue light lasers has proven effective in treating acne vulgaris8. One study using high-intensity, narrow-ban 405-420 nm light found “more than an 80% response to 420 nm acne phototherapy with a significant reduction of 59-67% of inflammatory acne lesions after only eight treatments of 8-15 minutes. The reduction in lesions was steady in the follow-ups at 2, 4 and 8 weeks after the end of therapy. Prolonged remission was evident in the 8 weeks after the end of therapy. No adverse effects or patient discomfort were noted in any of the patients.”9.

The reason blue light is effective is that it heats and destroys porphyrins accumulated in the Propionibacterium acnes bacteria. However, red light is also effective, has an anti-inflammatory effect, and penetrates deeper into the skin10.

Thus, many wavelengths in sunlight appear to reduce the risk of acne vulgaris.

Page last edited: 13 May 2011


  1. Al-Ameer, A. M. Al-Akloby, O. M. Demographic features and seasonal variations in patients with acne vulgaris in Saudi Arabia: a hospital-based study. International journal of dermatology. 2002 Dec; 41 (12): 870-1.
  2. Tamer, E. Ilhan, M. N. Polat, M. Lenk, N. Alli, N. Prevalence of skin diseases among pediatric patients in Turkey. The Journal of dermatology. 2008 Jul; 35 (7): 413-8.
  3. Jha, A. K. Gurung, D. Seasonal variation of skin diseases in Nepal: a hospital based annual study of out-patient visits. Nepal Medical College journal : NMCJ. 2006 Dec; 8 (4): 266-8.
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  8. Ammad, S. Gonzales, M. Edwards, C. Finlay, A. Y. Mills, C. An assessment of the efficacy of blue light phototherapy in the treatment of acne vulgaris. Journal of cosmetic dermatology. 2008 Sep; 7 (3): 180-8.
  9. Elman, M. Slatkine, M. Harth, Y. The effective treatment of acne vulgaris by a high-intensity, narrow band 405-420 nm light source. Journal of cosmetic and laser therapy : official publication of the European Society for Laser Dermatology. 2003 Jun; 5 (2): 111-7.
  10. Nouri, K. Villafradez-Diaz, L. M. Light/laser therapy in the treatment of acne vulgaris. Journal of cosmetic dermatology. 2005 Dec; 4 (4): 318-20.