Ask a doctor or pharmacist before using folic acid with any other medications, especially:
methotrexate;
nitrofurantoin;
pyrimethamine;
tetracycline;
a barbiturate such as phenobarbital or secobarbital; or
seizure medicine such as phenytoin or primidone.
This list is not complete. Other drugs may interact with folic acid, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.
 Folic acid drug interactions (more detail)
