I've been facing allergies when i'm outside and its caused by Sun. I'm sufferinf from it near about 4years. The causes is when I go outside, i cant withstand against the heat of the sun and lateron I turn red to those areas which are exposed directly. Right after turning red, my skin burns and it turns into hives. I used to take Allegra 180 but I'vr stopped it. Most of the time even if I'm outside, I coverup myself except my feets, neck, face and palms which gets exposed to Sun.