Hello,
Thank you for your query at DoctorSpring.com
Though there is not enough literature to conclusively point out the side effect profiles but it does have interaction with immunosuppressants like Cyclosporine, Birth control pills, e.t.c
Since you're not taking any medicine, you should not worry.
Also yes it may cause photosensitivity and also increase damage from prolonged exposure to sun, but this is not a reported side effect, more of a theoretical possibility, still using protective sunscreen is a good idea.
You can continue taking 900 mg, but do not exceed the dose in any way.
Regards.