Do any drugs interact with the effectiveness of oral contraceptives?
Certain drugs may interact with birth control pills to make them less effective in preventing pregnancy or cause an increase in breakthrough bleeding. Such drugs include rifampin; drugs used for epilepsy such as barbiturates (for example, phenobarbital), anticonvulsants such as carbamazepine (Tegretol is one brand of this drug), and phenytoin (Dilantin is one brand of this drug); phenylbutazone (Butazolidin is one brand), and possibly certain antibiotics.
