Fluconazole (brand name Diflucan) is used to treat vaginal yeast infections.
"Patients who are pregnant or actively trying to get pregnant should talk to their health care professionals about alternative treatment options for yeast infections," the FDA advised Tuesday.
The agency said it is evaluating the results of a recent Danish study that suggested a link between fluconazole and miscarriage, along with additional data and will release final conclusions and recommendations when the review is completed.
Current labeling information suggests that a single 150 milligram (mg) dose of oral fluconazole to treat vaginal yeast infection is safe to take during pregnancy. However, the FDA noted that in rare cases higher doses taken during pregnancy (400 mg to 800 mg a day) had been linked to abnormalities at birth.
In the Danish study, most of the fluconazole use appeared to be one or two doses of 150 mg.
"Until FDA's review is complete and more is understood about this study and other available data, FDA advises cautious prescribing of oral fluconazole in pregnancy," the agency said in a news release.
The agency noted that the U.S. Centers for Disease Control and Prevention recommends only antifungal creams to treat pregnant women with vaginal yeast infections -- even for longer periods than usual if the infections persist or recur.
While the Danish study showed that pregnant women treated with fluconazole had a greater risk of miscarriage than those who used an antifungal cream, it did not prove the drug causes miscarriages, the authors noted.
Still, "women who are trying to become pregnant or who are pregnant should avoid fluconazole," said Dr. Jennifer Wu, an obstetrician and gynecologist at Lenox Hill Hospital in New York City, when the Danish study results came out. "For these women, a topical medicine is the preferred treatment."
Fluconazole (available as a pill or suspension liquid) is the only oral drug used to treat yeast infections during pregnancy, Wu said.
The U.S. Office on Women's Health has more about vaginal yeast infections.
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