The folic acid in this medicine can lower the level of phenobarbital in your blood. That could make phenobarbital work less well, so seizures may be harder to control. Phenytoin, another epilepsy medicine, may be affected the same way. If you take phenobarbital, talk to your doctor before you start this combination. Don't stop or change your epilepsy medicine on your own.
These medicines are often taken together with some care. Your doctor may change a dose, space them apart or check on you more often. Make sure your doctor and pharmacist know you take both.