ReviewDrug interactions between oral contraceptives and antibiotics
Section snippets
Sources
Published studies from 1966 through December 1999 were identified through MEDLINE and Lexis/Nexis Medical Library searches (without language restriction) using the term “oral contraceptives,” cross-indexed with “antibiotics,” “adverse effects,” and “pregnancy.” Related articles in the MEDLINE database using the additional MeSH term “drug interactions” also were identified. A total of 167 articles were retrieved for analysis, and another 32 articles were identified by review of the references
Clinical reports of antibiotics apparently causing OC failure
The first report of potential interactions between antibiotics and OCs appeared in 1971 when Reimers and Jezek6 reported an increased incidence of intermenstrual breakthrough bleeding in 38 of 51 women treated concomitantly with OCs and rifampin. Shortly thereafter, rifampin was implicated in five unplanned pregnancies among 88 women with tuberculosis who were taking both rifampin and OCs. Another 62 women suffered from menstrual irregularities.7 Over the next decade, another 13 reports
Discussion
Based on retrospective case series (usually without control groups) and individual case reports, it has long been suspected that the prescription of oral antibiotics to women using OCs may occasionally result in OC failure in otherwise compliant patients. Caution must be exercised in the interpretation of these data because of recall bias and the possibility that individuals may underreport poor compliance when they are confronted with an unplanned (or unwanted) pregnancy or are requesting
Conclusions
The following statements, recommended by the Council on Scientific Affairs, were adopted as American Medical Association policy in June 2000.
- 1.
Women prescribed rifampin concomitantly with OCs faced significant risk of OC failure and should be counseled about the additional use of nonhormonal contraceptive methods during the course of rifampin therapy.
- 2.
Women using combined OCs should be informed about the small risk of interactions with antibiotics and that it is not possible to identify in
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Cited by (0)
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Members and staff of the Council on Scientific Affairs at the time this report was prepared were: Myron Genel, MD (Chair), New Haven, CT; Michael A. Williams, MD (Chair-Elect), Baltimore, MD; Roy D. Altman, MD, Miami, FL; Scott D. Deitchman, MD, MPH, Duluth, GA; J. Chris Hawk III, MD, Charleston, SC; John P. Howe III, MD, San Antonio, TX; Hillary D. Johnson, St. Louis, MO; Nancy H. Nielsen, MD, PhD, Buffalo, NY; John F. Schneider, MD, PhD, Chicago, IL; Melvyn L. Sterling, MD, FACP, Orange, CA; Zoltan Trizna, MD, PhD, Galveston, TX; and Donald C. Young, MD, Iowa City, IA. Staff: Barry D. Dickinson, PhD (Secretary); James M. Lyznicki, MS, MPH (Assistant Secretary); and Marsha Meyer (Editor), Chicago, IL.