Which medication prescribed for active TB may interfere with oral contraceptives?

Rifampin is known to interact with hormonal contraceptives, including oral birth control pills. This medication enhances the metabolism of various substances through the induction of liver enzymes, particularly those in the cytochrome P450 system. As a result, when rifampin is taken concurrently with oral contraceptives, it can decrease their effectiveness by lowering the levels of hormones like estrogen and progestin in the blood. Consequently, patients on rifampin are advised to consider additional or alternative forms of contraception to prevent unintended pregnancies.

Isoniazid, ethambutol, and pyrazinamide, while being integral in the treatment of tuberculosis, do not exhibit the same level of enzymatic induction that affects the metabolism of oral contraceptives. Thus, they do not significantly interfere with the efficacy of hormonal contraceptives as rifampin does. This understanding of pharmacological interactions is crucial for managing patients with active tuberculosis effectively while safeguarding their reproductive health.