Cold sores, also known as fever blisters, are small, painful blisters that usually rupture spontaneously after three or four days, leaving behind a raw, weeping, open sore. Although they result from infection with the herpes simplex virus, not all people who have the virus develop cold sores. Exposure to ultraviolet radiation from the sun, stress, illness and dental work are just a few of the recognized triggers for cold sores, according to the Academy of General Dentistry. While some --- like stress, illness and dental work --- are unavoidable, wearing sunscreen reduces your risk of cold sores caused by ultraviolet radiation.
Significance
In the January 2008 issue of the "International Journal of Epidemiology," researcher Robyn M. Lucas, Ph.D. and her colleagues from the Australian National University attempt to quantify the impact of ultraviolet light exposure on the health problems of people around the world. According to Dr. Lucas, ultraviolet light from the sun suppresses the activity of the immune system within exposed skin. The result, Dr. Lucas says, is often cold sores. Dr. Lucas' data implicate sun exposure in 25 to 50 percent of cold sore outbreaks.
Function
MayoClinic.com says that there are two types of sunscreens: physical and chemical. Physical sunscreens contain ingredients like zinc oxide or titanium dioxide that reflect ultraviolet light away from your skin. Chemical sunscreens contain ingredients such as avobenzone or oxybenzone that absorb ultraviolet radiation, so that the skin cells beneath it do not. Most sunscreens contain more than one ingredient in order to provide complete coverage against different wavelengths of ultraviolet light, or UVA and UVB, as they are commonly known.
Application
You can purchase sunscreen in the form of cream, lotion, gel, stick, spray and lip balm. To prevent cold sores, you may wish to use a combination of cream or lotion on your face, followed by lip balm on your lips. You should apply sunscreen a few minutes before you step into the sun, so that it has time to absorb into your skin. The National Institutes of Health's MedlinePlus website recommends reapplying every two hours that you spend in the sun, or every 80 minutes if you are in water or perspiring heavily. Although sunscreens come in strengths -- called sun protection factor or SPF -- up to 30, MedlinePlus recommends consulting with a doctor or pharmacist to determine your individual needs.
Risks
Sunscreen can cause local skin irritation. If you experience this, ask your doctor or pharmacist to recommend a different brand. Since the body requires sunlight to produce vitamin D, Dr. Lucas notes that use of sunscreen increases the risk of vitamin D deficiency. Eating foods naturally rich in vitamin D, such as egg yolks or saltwater fish, or fortified with vitamin D, such as milk and some grain products, wards off this complication. If you don't eat any of these foods regularly, consider taking a multivitamin that contains vitamin D.
Benefits
Dr. Lucas' results show that sun exposure contributes to 25 to 50 percent of cold sores. If you live in a sunny area or your job requires you to spend a lot of time in the sun, you may find that using sunscreen reduces the number of cold sores you experience by even more than 50 percent. In addition to preventing cold sores, sunscreen also protects against other problems such as skin cancer and skin aging.
Considerations
Sunscreen isn't the only option for preventing cold sores. Hats and other headgear such as burkas also offer sun protection, as does limiting outdoor time or staying under an umbrella or canopy. Sunscreen does not replace conventional medical treatment for cold sores or any other condition. People with severe or frequent cold sores, or cold sores that last longer than two weeks should see a doctor.
References
- Academy of General Dentistry: What Are Cold Sores?
- "International Journal of Epidemiology"; Estimating the Global Disease Burden Due to Ultraviolet Radiation Exposure; Robyn M. Lucas, Ph.D. et al.; January 2008
- MayoClinic.com: Sunscreen: Answers to Your Burning Questions
- National Institutes of Health: Vitamin D
- "Archives of Internal Medicine"; The Treatment of Herpes Simplex Infections; Christina Cernik, M.D., et al.; June 9, 2008
