Which medication will interfere with the effectiveness of oral contraceptives?

Carbamazepine is known to interfere with the effectiveness of oral contraceptives due to its enzyme-inducing properties. It belongs to a class of medications that can increase the metabolism of oral contraceptive hormones, thereby leading to reduced plasma levels of these hormones. This interaction can decrease the contraceptive efficacy, potentially resulting in unintended pregnancies.

In contrast, the other medications listed do not have this effect. Sumatriptan, typically used for migraine treatment, does not affect hormone levels and therefore does not interfere with contraceptives. Atenolol, a medication for hypertension and certain heart conditions, also does not interact with oral contraceptives in a way that would compromise their effectiveness. Glipizide, an oral medication for managing diabetes, similarly does not have any significant interaction with hormonal contraceptives.