Cold sores are lesions on the lips or the skin around the mouth that are caused by herpes simplex virus 1 (HSV-1). They are an exceedingly common and annoying fact of life, but most people who suffer only get them occasionally. Some people who are especially susceptible suffer from recurring cold sores and may have several outbreaks every year.
This might be a signal that the immune system is not functioning properly, but usually it is hard to tell why such people are so vulnerable. Both stress and sunshine can suppress the immune system somewhat, and they have both been linked to outbreaks. One reader found a different explanation that led to an intriguing solution.
What Triggers Recurring Cold Sores?
Q. I suffered from recurring cold sores for years. No dermatologist or other health care provider had a good answer.
Ophthalmologist to the Rescue:
Then my ophthalmologist informed me that the herpes virus is easily triggered by sunlight through the retina. This corresponded perfectly with my outbreaks happening immediately after being on a glacier or a day of kayaking.
I began wearing dark sunglasses (and in the case of climbing, wrap-around alpine glasses to stop snow glare) to keep the sunlight from entering my retina and triggering an outbreak. It has made a world of difference. Since gaining this awareness I now have maybe one outbreak a year versus 5 or 6 year.
Ultraviolet Light as a Trigger:
A. Exposure to ultraviolet (UV) radiation (sunlight) has long been known to trigger herpes outbreaks. UV exposure may stimulate viral activity while simultaneously depressing the immune system. Many lip balms contain sunblock, presumably to reduce cold sore outbreaks.
Analyzing the results from the Herpetic Eye Disease Study, a long-term randomized controlled trial, showed that exposure to strong sunlight was linked to the risk of a herpes lesion recurrence (American Journal of Epidemiology, Jan. 15, 2014). We have been unable to find any studies supporting your use of dark sunglasses to prevent cold sore recurrence, but we’re glad to learn how well it works for you.
The Benefits of Sunglasses:
Anyone spending time outside as you do should invest in a good pair of sunglasses regardless of whether or not they help avoid cold sores. Look for a quality pair that blocks both UVA and UVB radiation; it is one of the best things you can do to help prevent the development of cataracts.