Monotherapy with lamotrigine or levetiracetam, or valproic acid (sodium valproate), should be offered as first-line treatment for generalized onset seizures in men/boys and women/girls who are not of childbearing potential. In women and girls of childbearing potential with generalized onset seizures, lamotrigine or levetiracetam should be offered as first-line monotherapy. If the first monotherapy is not successful for generalized onset seizures, an alternative first-line monotherapy should be tried. Valproic acid (sodium valproate) is not recommended in women and girls of childbearing potential owing to the high risk of birth defects and neurodevelopmental disorders in children exposed to valproic acid (sodium valproate) in the womb. If lamotrigine, levetiracetam and valproic acid (sodium valproate) are not available for generalized onset seizures, monotherapy with either phenytoin or phenobarbital can be considered.