I take Imuran and I am extra cautious about wearing and reapplying sunblock. However I get horrible headaches if I am not wearing sunglasses. I have had this problem for as long as I can remember, even as a child. When it is really bright out I also have to wear a hat with a good brim because of the light, what I end up with are horrible tension headaches from squinting.
That's interesting. I spent a lot of time in the sun as a child. I've never had issues. Until this year (or maybe last year, idk). One other thing that I have problems with is dry eyes.
Generally, the headaches start in 5-10 minutes and get worse as time goes on. Even standing in the shade with the sunlight reflecting from the asphalt bothers me. And yea, I always squint.