Is Metronidazole (Flagyl) safe during pregnancy?
What the FDA-approved label for Metronidazole (Flagyl) actually states in its Pregnancy Risk Summary — not a secondhand verdict. The decision is one to make with your prescriber.
What the label’s pregnancy summary says
The label states there are no adequate and well-controlled studies in pregnant women, but published case-control, cohort, and two meta-analyses covering more than 5,000 pregnant women (many with first-trimester exposure) mostly did not show an increased risk of congenital anomalies or other adverse fetal outcomes. One study suggested an increased risk of cleft lip (with or without cleft palate) that was not confirmed in later work. Metronidazole crosses the placenta and its effects on human fetal organogenesis are not known; animal reproduction studies at doses similar to the maximum human dose showed no evidence of fetal harm. The label does not establish a clear risk. Anyone who is or may become pregnant should discuss use with their prescriber.
Frequently asked questions
Is Metronidazole safe to take during pregnancy?
The label's §8.1 does not report a clear risk for Metronidazole (summary above), which is reassuring but is not the same as a guarantee of safety — no drug is studied in pregnancy the way it is in other adults. Use it in pregnancy only after discussing it with your prescriber. The one universal rule: do not start or stop a medication in pregnancy without medical advice — an untreated condition can carry its own risk to a pregnancy.
What does the FDA label say about Metronidazole in pregnancy?
The summary above is transcribed from the label's Pregnancy Risk Summary (§8.1). Since 2015 FDA labels replaced the old A/B/C/D/X letter categories with a narrative that describes what human and animal data actually show, which is what you are reading here — not a single letter grade.
Is Metronidazole safe while breastfeeding?
That is a separate question the label answers in a different section (§8.2, Lactation), and it does not always match the pregnancy verdict. This page covers pregnancy only. For breastfeeding, ask your prescriber or pharmacist, or check the NIH LactMed database, which summarizes the drug-in-breast-milk evidence.
More guides for Metronidazole
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The pregnancy information is transcribed from the drug’s FDA-approved label (§8.1) and mirrors what the label states — “insufficient data” is never rounded up to “safe.” This is general reference information, not medical advice. Whether to take any medication in pregnancy is a decision for you and your prescriber; do not start or stop a drug on your own, because an untreated condition can also carry risk.