Sunlight is an important causative factor of recurrent herpes simplex

Cutis. 2004 Nov;74(5 Suppl):14-8.


To evaluate the role of exposure to solar UV radiation (UVR) in primary and recurrent herpes simplex virus 1 (HSV-1) infections, we investigated the self-reported cause of infection among diagnosed patients in Hyogo Prefecture, Japan. Among 4295 infected patients, 3678 had HSV-1, and 2656 of those patients (72.2%) had a recurrent flare-up. Fatigue was the most commonly reported cause of a flare-up among all patients, followed by the common cold and sun exposure. Sun-induced HSV-1 flare-up was reported by 10.4% of the total study population. However, this increased to 19.7% among patients diagnosed in July and August, to 28% among patients younger than 30 years diagnosed in July and August, and to 40% among patients younger than 30 years diagnosed in July and August with a recurrent infection. These results suggest the important role of solar UVR in the development of recurrent HSV-1, possibly due to UVR-induced immunosuppression or direct reactivation of HSV-1 in the neural ganglia.

Publication types

  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Age Factors
  • Aged
  • Aged, 80 and over
  • Child
  • Child, Preschool
  • Fatigue / complications
  • Female
  • Herpes Simplex / etiology*
  • Herpesvirus 1, Human / radiation effects*
  • Humans
  • Infant
  • Leisure Activities
  • Male
  • Middle Aged
  • Recurrence
  • Seasons
  • Sex Factors
  • Sunlight / adverse effects*
  • Ultraviolet Rays / adverse effects*