I did not take any supplements while on Dilantin. I was in my twenties at the time. I was diagnosed with osteoporosis in my late thirties or early forties after many fractures were regularly sustained. After 20 yr, treatment my osteoporosis for has become osteopeania (a decreased amount of bone). I am now taking an additional vitamin D supplement because 3 years ago my vitamin levels were low.
I take zonisamide and Depakote in addition to lamotrigine.