Taking B6 with levetiracetam

Hi question about epileptic medication . My son has been on Levetiracetam 2.5mg for three weeks he’s having some mood side effects. I have seen online that giving B6 vitamin pyridoxine may help . Does anybody have any experience with this ? Thank you . My son is 18 and he is taking high doses of B5 and B Complex too . What dose would be safe to give ?