Loss of oral contraceptive efficacy by concurrent antibiotic administration.

There are approximately 10 million women in the United States who are currently taking oral contraceptives on a daily basis. Although the actual number is not known, it is also estimated that a large number of these same women are on concomitant drug therapy. In recent years there have been a number of published reports linking a loss of contraceptive efficacy with the concurrent administration of other drugs, including antibiotics. Whereas the actual risk of drug interaction between antibiotics and oral contraceptives is yet unknown, it is important that women who are on oral contraceptive therapy be aware of possible contraceptive failure. This article reviews the published incidence of oral contraceptive/antibiotic interaction, along with a discussion of the possible mechanisms by which this interaction occurs. Recommendations are also presented for the health management of women taking oral contraceptives and other prescribed drugs.