The clinical relevance of the inductive properties of carbamazepine, phenytoin, phenobarbital and primidone and the inhibitory properties of valproic acid and some antidepressants are well understood; correction factors are provided if appropriate DI studies have been completed. More PK studies are needed for: i) antiepileptics with potent inductive effects for all recently approved antidepressants; ii) high doses of mild CYP3A4 inducers, such as clobazam, eslicarbazepine, oxcarbazepine, rufinamide and topiramate for reboxetine and vilazodone; iii) valproate as a possible inhibitor, mild inducer or both a mild inducer and competitive inhibitor of some antidepressants; and iv) inhibitory effects of long-term fluoxetine use on clobazam, lacosamide, phenobarbital, primidone, carbamazepine, felbamate, tiagabine and zonisamide. Possible synergistic or additive beneficial PD DIs in generalized anxiety disorder, chronic pain, migraine prophylaxis, weight control and menopausal symptoms need study.