How long should anticonvulsant be taken?

As long as necessary. Your neurologist with specialization in seizure disorders will determine the length of your anticonvulsant therapy depending on your particular type of seizures, their frequency and other comorbidities. Be sure to ask your doctor to switch you off valproic acid and take 1-5 mg of Folic Acid daily if planning to get pregnant. Do not drive unless your neurologists allows you to.