Do Antibiotics Reduce Efficacy of Hormonal Contraception?

Many clinicians and pharmacists advise that women using hormonal contraception (HC) employ backup contraception during treatment with antibiotics. Although rifampin and other rifamycin antibiotics induce hepatic enzymes that metabolize HC steroids, other antibiotics do not have such pharmacokinetic effects. Investigators performed a systematic review of 29 studies addressing pregnancy rates, serum progesterone levels, sonographic evidence of ovulation, changes in bleeding patterns, and pharmacokinetics in women using nonrifamycin antibiotics concurrently with HC.

Concomitant antibiotic use (including penicillins, cephalosporins, quinolones, tetracyclines, macrolides, trimethoprim sulfamethoxazole, metronidazole, dapsone, and isoniazid/strept…