Antibiotic Interference with Oral Contraceptives: Can a Dental Visit Make you Pregnant?

Oral contraceptives are a safe and effective form of birth control used by millions of women in the United States and around the world. There have been anecdotal reports of unintended pregnancies after antibiotics were prescribed to women on oral contraceptives. Dentists and physicians have therefore been advised to warn female patients on oral contraceptives of a potential interaction and to advise additional forms of contraception when prescribing antibiotics. This issue has caused consternation among dentists, physicians, and patients, coming to a climax in the lay media with the headline “A Dentist Visit Can Make You Pregnant” in a supermarket tabloid. Fortunately, scientific studies have failed to show any decrease in oral contraceptive efficacy with any antibiotics except for one: rifampin, which is not typically used in dentistry. It is therefore not necessary to warn patients of a potential interaction between antibiotics used in dentistry and oral contraceptives when scientific evidence has consistently and repeatedly failed to support such an interaction. The history of modern birth control can be traced back to 3000 BC, when condoms were made out of fish bladders, linen sheaths, or animal intestines. By 1838, condoms and diaphragms were made out of vulcanized rubber. Margaret Sanger was a birth control activist who helped reproductive physiologist Gregory Pincus obtain a small grant to begin contraceptive research in 1951. In 1957, the United States Food and Drug Administration (FDA) approved an oral contraceptive (Envoid) for menstrual disorders. In 1960, the FDA approved the first hormonal oral contraceptive for birth control. The pill was not available to married women in all states until a Supreme Court ruling in 1965. It became available to unmarried women in all states after another Supreme Court ruling in 1972. Today there are more than 100 million women using birth control pills globally, with more than 11 million in the United States.1 Modern oral contraceptives typically contain two hormones, estrogen and progestin. It is possible for various medications to impact oral contraceptive efficacy, causing unintended pregnancies. There have been many classes of drugs implicated in oral contraceptive failure, including antibiotics, anticonvulsants, antidepressants, antihistamines, thyroid hormones, diuretics, vitamins, and antiulcer medications [Table 1].3 In the 1970s, the potent enzyme-inducer rifampin, an antibiotic used for tuberculosis treatment, was first implicated in oral contraceptive failure due to its interaction with the oral contraceptive, rendering them less effective. Since then, many other antibiotics have also been blamed for unwanted pregnancies and their interaction. As a result, dentists and physicians have been indoctrinated with the fear of “wrongful birth”: an unwanted pregnancy due to a possible interaction of which the woman was not informed. A manufacturer’s warning of a possible interaction is included in many package inserts of antibiotics and oral contraceptive formulations. It is alleged that if the dentist or physician does not warn of a possible interaction and advise additional birth control methods when on the antibiotic, then he or she can be legally liable for this “wrongful birth,” including child support payments until the child is 18 years of age. Table 1. Drugs implicated in oral contraceptive failure.