30 - Drugs that May Reduce Combined Hormonal Contraceptive Efficacy

Interacting Drug Documentation Antituberculous     Rifampin Established; reduced efficacy if <50 microg EE Antifungals     Griseofulvin Strongly suspected Anticonvulsants and sedatives     Phenytoin, mephenytoin, phenobarbital, primidone, carbamzepine, ethosuximide Strongly suspected; reduced efficacy if <50 microg EE; trials lacking Antibiotics     Tetracycline, doxycycline Two small studies find no association   Penicillins No association documented   Ciprofloxacin No effect on efficacy of a 30 microg EE + desogestrel pill   Ofloxacin No effect on efficacy of a 30 microg EE + levonorgestrel pill Antiretrovirals Variable effects; see manufacturer or other

EE = ethinyl estradiol.