I was on it for only one and a half years--after seizures were recorded in the EMU during my presurgical workup they dumped me on a high
dose, since you can start off on a high
dose--and I have osteopenia, primarily on my upper femur on both sides. As I only recently learned, dilantin is especially bad for premenopausal women (not good for anyone, of course) even if you're on it for only a year, for example.