Effect of Antiepileptic Drugs on Oral Contraceptives

Abstract

We found no studies that measure, or even estimate, any increase in pregnancy rates in women taking antiepileptic drugs. Antiepileptic drugs known to induce the hepatic cytochrome P450 (CYP450) isoenzyme cause decreased sex hormone levels in women taking oral contraceptives, raising the potential for decreased effectiveness of oral contraceptives and increased risk of unplanned pregnancy. (Strength of Recommendation [SOR]: C, based on small cohort studies). Antiepileptic drugs that do not induce this hepatic isoenzyme are not thought to compromise the effectiveness of oral contraceptives. (SOR: C, based on small cohort studies and randomized controlled trials).