Østrogen - og gestagenmetabolismen kan blive forøget ved samtidig indtagelse af stoffer, som er kendt for at påvirke lægemiddelmetaboliserende enzymer, specielt cytochrom P450 enzymer såsom antiepileptika (fx barbiturater, phenytoin, carbamazepin), eller bredspektret antibiotika (rifampicin, rifabutin, nevirapin og efavirenz).
The metabolism of oestrogens and progestagens may be increased by concomitant use of substances known to induce drug-metabolising enzymes, specifically cytochrome P450 enzymes such as anticonvulsants (e.g. phenobarbital, phenytoin, carbamazepin) and anti-infectives (e.g. rifampicin, rifabutin, nevirapine, efavirenz).