Updated January 6, 2016
In August 2011 the FDA changed the classification of Fluconazole (Brand Name: Diflucan), a commonly prescribed antifungal medication taken orally for the treatment of vaginal yeast infections, to a Category D drug. This means that there is evidence of human fetal risk but that benefits may warrant use of the drug in pregnant women only when medically necessary. Yet it is still commonly prescribed.
Fluconazole has been found to cause birth defects in infants born to mothers who took it in high doses (400-800 mg/day) during the first trimester of pregnancy, confirmed again recently in a review done in Denmark using national health registries t review outcomes in each pregnancy in which a prescription for oral fluconazole was filled after the sixth week of pregnancy. These were were matched with up to four pregnancies without fluconazole exposure. Over 1.4 million pregnancies from 1997 through 2013 were reviewed.
Miscarriage occurred (between 7 and 22 weeks' gestation) significantly more often in exposed than unexposed pregnancies. The oral drug (compared to vaginal insertion) was associated with significantly higher risk of miscarriage.
Previous research has suggested a link between high-dose oral fluconazole therapy and congenital malformations. Birth defects included brachycephaly (short, broad head), abnormal facial structure, abnormal skull development, cleft palate, bowing of the femurs, thin ribs and long bones, arthrogryposis, and congenital heart disease. It is usually only used in such high doses for women who are immunocompromised – for example, with HIV/AIDS or who are undergoing chemotherapy – and develop a systemic fungal infection. For otherwise healthy women, a yeast infection is anything but life threatening – though when bad it can feel like there's a red alert going on down there!
Typical dosing of fluconazole for common vaginal yeast infections is 150 mg as a one-time dose. The FDA stated that the risks do not appear to be associated with this single 150-mg dose. At this dose the drug remains category C, which means there are no adequate studies in humans and, although studies of animals have shown an adverse effect on the fetus, potential benefits may warrant use of the drug in pregnant women despite potential risks. There are few published studies of in utero exposure to low doses of fluconazole. While most showed no consistent pattern of abnormalities, the studies have been too small to accurately detect an increased risk for major birth defects overall and none of the studies were large enough to accurately detect an increased risk for rare or unique birth defects or syndromes.
Given the identified risks of high doses, and the uncertain safety of typical doses, I find it hard to understand why a vulnerable population – pregnant women and their babies – continue to be exposed to a potentially risky pharmaceutical treatment at any dose when simple, safe, and effective remedies for common vaginal infections are available. Diflucan has been a medical mainstay for treating vaginal yeast infections for decades. For your garden-variety infection, a single dose at 150 mg might do the trick. For many women, however, more than one dose is needed. I don't know about you ladies, but the thought of taking a drug that is associated with birth defects, even if rare, makes me consider the alternatives – whether I'm pregnant or not.
Read Treating Vaginal Infections Naturally for more information on natural approaches.