Cold sores caused by the Herpes simplex virus are usually associated with winter colds and flu, stress and being a bit run down. However UV light is a well known trigger for the herpes simplex virus. Many people clear their desks, pack up the family and car, sighing with relief that the summer holidays have arrived and then find a few days into the holiday that the sun sea and sand has let out the stowaway. Approximately 90% of the adult population has at some point been infected with the Herpes simplex virus and for many it does not cause too many problems. The virus usually presents as a common cold sore but it can also present as mouth ulcers, in the eyes (ocular) and in between the fingers (herpes whitlow).
Numerous studies have established the relationship between UV light and the herpes simplex virus.
A new study, the Herpetic Disease Study (HEDS) investigated the relationship between the UV index and recurrences of ocular simplex virus in 700+ people over a period of fifteen months. Results showed that when the UV index was high, spending more than 8 hours a week outside led to an increased number of ocular herpes outbreaks. An older study with 4295 participating patients with recurrent Herpes simplex 1 infection showed that 10% of the study group have recurrences of cold sores at least once a year but that this rose to 40% in July and August and the rate of recurrences was higher in younger people.
Cold sores can ruin a holiday for children and young people. Children in particular can find it very difficult to eat and whilst the sea water may help, it also hurts.
If you or your children have cold sores it is important to know what triggers them and what works to prevent them. People have different trigger factors and some treatments work for some and not for others. See the Patient QI Cold Sore Treatment Strategy for more information.
Ludema et al. Association between unprotected ultraviolet radiation exposure and recurrence of ocular herpes simplex virus. Am J Epidmiolo. Jan 2014.
Ichihashi et al. Sunlight is an important causative factor of recurrrent herpes simplex. Cutis Nov 2004.