The nurse is counseling a woman who will be starting rifampin. The patient is currently taking oral contraceptives. Which statement is true regarding rifampin therapy for this patient?

A higher dose of rifampin will be necessary because of the contraceptive.

The incidence of adverse effects is greater if the two drugs are taken together.

Women have a high risk for thrombophlebitis while on this drug.

Oral contraceptives are less effective while the patient is taking rifampin.