For many years, dentists have been advised that female patients who use oral contraceptives should use additional barrier contraceptive protection during and until the first week after antibiotic therapy. Anecdotal case reports of oral contraceptive failures appeared to support this practice. An article by Lapp notes that recent research has concluded that such practice is not based on sound evidence. The author cites studies showing that the unintended pregnancy rate among users of oral contraceptives who concomitantly used tetracycline, erythromycin, or minocycline was not significantly different from the generally calculated failure rate for users of the contraceptives. Antibiotics that have not been proven to reduce oral contraceptive efficacy include cephalosporins, penicillins, clindamycin, tetracyclines, macrolides, and quinolones. The American College of Obstetricians and Gynecologists has used existing evidence to conclude that tetracycline, doxycycline, ampicillin, and metronidazole do not affect steroid levels produced by oral contraceptives. One exception to this is the antituberculosis drug rifampin, which does interfere with oral contraceptive efficacy but is not usually prescribed by dentists.
(Source: GDA Action, The Journal of the Georgia Dental Association, February 2005)
