To reiterate. Flying is safe. There are at least three aspects of flying to keep in mind. First, as Mark mentioned, overstimulation can be a problem. Second, if you have vestibular issues, the motion of the plane can cause problems (trust me on this one!). Finally, the altitude can, in theory, constrict the flow of blood to the brain, which could effect your headache if you have one. Know this before you fly and you will be better off. If you feel worse, it will pass.