BeeZee
Aron...I have been plagued with these blisters most of my life...I was told that stress, any illness and yes, the sun, could cause an outbreak. The blisters come from the Herpes Zoster virus (chicken pox) which stays in your body and anything that breaks down your resistence can cause an outbreak. Put a SPF 30 (or more) on your lips while sunning, and at the first sign of a blister put an ointment in a tube called "herpecin" it will not stop the process, but it might make the duration of an outbreak shorter, and ease some of the discomfort. Good luck. Bz