Estradiol + Dydrogesterone Efavirenz
ModerateEfavirenz can make Estradiol + Dydrogesterone work less well. Efavirenz speeds up certain liver enzymes (the P450 enzymes 2B6, 3A4, 3A5 and 3A7). These enzymes break down oestrogen and progestogen hormones, so your body clears them faster than it should. Less of the hormone stays in your body, and the medicine may not give you its full benefit. Other medicines that act in the same way include phenobarbital, phenytoin, carbamazepine, rifampicin, rifabutin and nevirapine.
These medicines are often taken together with some care. Your doctor may change a dose, space them apart or check on you more often. Make sure your doctor and pharmacist know you take both.