I used to get itch all over when I was in the sun. No sunburn or rash, it was weird. First time it happened was in Hawaii, I ended up in the emergengy room after a sleepless night. They gave me IV Benadryl and I was OK after a few hours. I was on 6mp and Asacol at the time.
I ended up buying hats and long sleeve shirts for the rest of my vacation in Hawaii!