While most of us don't think about this very often, you can get a sunburn on your lips just like you can anywhere else. This is the reason that so many of the lip balms that we use contain sunscreen, which you might not have even noticed. Dry and swollen lips can certainly be a sign of a sunburn, but it could alternatively be a sign of something as simple as chapped lips from being too dry and perhaps having gotten some wind burn or other irritation. Just like the rest of your skin, the lips are very sensitive to prolonged exposure, and should be protected. Given that they are regularly moistened with saliva and then have to dry, adding a waxy coating such as a lip balm to help keep the moisture in can be especially helpful for helping them heal quickly. Making sure that your balm also contains UV protection will make sure that your lips don't get sunburned in the future. Lips are especially problematic as they are subjected to repeated moist/dry cycles, and the wax in balms can help to break these. Please use sunscreen, and please talk to your doctor
to make sure the irritation and dryness aren't caused by a more serious issue.