Mother Nature can take a toll on your body. Wind and cold can both trigger cold sores. So, too, can the sun.
Sun exposure is a well-known cold sore trigger. Ultraviolent (UV) light causes skin damage, and any chinks in your lips' armor can allow the cold sore virus to spring forth in all its unseemliness. We're not talking sunburn-type exposure – for some sufferers, just a little sun can cause a lot of problems in terms of an outbreak. And of course, hot, dry, sunny days can contribute to chapped lips, especially when there's a breeze.
Applying sunscreen to your lips may help prevent sun-induced recurrences of cold sores. Look for a sunscreen designed especially for the lips that has an SPF of 15 or higher. Or, choose a lipstick that contains sunscreen. But keep in mind that water, sweat, or simply licking your lips can minimize the benefits of sunscreen or cause it to wear away quickly. You may need to reapply the product throughout the day if you're often outdoors. (Of course, if the product touches your lips, do not share it with others.)
Unfortunately, applying sunscreen regularly may contribute to oiliness in the skin and actually block pores in some users. Blocked pores, too, can spark irritation that results in cold sores.