9 drugs that interact with oral contraceptives

Drugs which increase the metabolism of oestrogens and progestogens can reduce the efficacy of oral contraceptives.

This occurs when the drugs induce the activity of metabolising enzymes in the liver and intestinal mucosa. One example is  the complementary medicine St John's wort which can potentially lead to a failure of oral contraception.

Although not an enzyme inducer, griseofulvin can also potentially reduce