Number 9 Oral Contraceptives Drug Interactions Contraceptive hormones can interact with certain other drugs, reducing the effectiveness of OCs or modifying the effects of the other drugs. If a user of low-dose OCs is taking any of these drugs, she can increase her contraceptive protection by using an additional method of contraception while continuing with her daily pill, or she can change to an OC with 50 g estrogen. If she uses the drug for less than a month, she should continue using her back-up contraceptive method or different pill regimen for at least a week after stopping the drug. If her cycle of 21 contraceptive pills ends during this week, for best protection she can start the next cycle of pills immediately. Women who must take any of these drugs for a long time, such as women being treated for tuberculosis, may want to consider another contraceptive method.
Oral contraceptives can speed up the metabolism of certain other drugs.