Is Nitrofurantoin safe during pregnancy?
What the FDA-approved label for Nitrofurantoin 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 contraindicates nitrofurantoin in pregnant women at term (38 to 42 weeks gestation), during labor and delivery, or when the onset of labor is imminent, because of the risk of hemolytic anemia in the newborn (immature erythrocyte enzyme systems). For earlier pregnancy, the label says published epidemiological studies have reported inconsistent findings on first-trimester use and major birth defects and cannot definitively establish the presence or absence of risk; the limited studies available have not identified drug-associated risks of major birth defects, miscarriage, or other adverse outcomes, and animal studies showed no fetal harm at up to 6 times the human dose. Anyone who is or may become pregnant should discuss use with their prescriber.
Frequently asked questions
Is Nitrofurantoin safe to take during pregnancy?
The label flags a real concern for Nitrofurantoin — see the summary above. This is not a drug to start or continue in pregnancy on your own; it needs a prescriber weighing the specific risks against the reason you would take it. 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 Nitrofurantoin 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 Nitrofurantoin 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.
The questions people actually ask about nitrofurantoin in pregnancy
Answered by MotherToBaby, the fact sheets written by the Organization of Teratology Information Specialists and published through the NIH. Quoted in full — we do not condense them.
I take nitrofurantoin. Can it make it harder for me to get pregnant?
It is not known if nitrofurantoin can make it harder to get pregnant.
Does taking nitrofurantoin increase the chance of miscarriage?
Miscarriage is common and can occur in any pregnancy for many different reasons. Two studies including 173 pregnancies did not find an association with nitrofurantoin use and an increased chance for miscarriage. However, people with untreated urine infections might have a greater chance for miscarriage.
Does taking nitrofurantoin increase the chance of birth defects?
Every pregnancy starts out with a 3-5% chance of having a birth defect. This is called the background risk. Most studies with nitrofurantoin do not suggest an increased chance of birth defects. Some studies on nitrofurantoin have suggested an increased chance of birth defects with use in pregnancy. However, study design flaws make some of the results in these studies questionable. There are also many studies on nitrofurantoin use in pregnancy that did not find birth defects. Overall, an increased chance for birth defects has not been confirmed.
Does taking nitrofurantoin in pregnancy increase the chance of other pregnancy-related problems?
It is not known if nitrofurantoin can cause other pregnancy-related problems, such as preterm delivery (birth before week 37) or low birth weight (weighing less than 5 pounds, 8 ounces [2500 grams] at birth). However, people with untreated urine infections might have a greater chance for these and other pregnancy complications, including preeclampsia (high blood pressure and problems with organs, such as the kidneys) that can lead to seizures (called eclampsia), and cesarean section (C-section).
There have been reports of newborns with hemolytic anemia (breakdown of red blood cells) when they were exposed to nitrofurantoin late in pregnancy. For this reason, the manufacturer has recommended using different antibiotics to treat urine infections later in pregnancy.
Does taking nitrofurantoin in pregnancy affect future behavior or learning for the child?
Studies have not been done to see if nitrofurantoin can cause behavior or learning issues for the child.
If a male takes nitrofurantoin, could it affect fertility or increase the chance of birth defects?
When nitrofurantoin was given to males at doses higher than typically used for 2 weeks, sperm production was low or stopped in 13 out of the 36 study participants. Low sperm production could affect fertility (ability to get partner pregnant). However, use of typical doses of 100mg twice daily for one week did not have this same effect. This means that with typical use, nitrofurantoin is unlikely to affect male fertility. In general, exposures that fathers or sperm donors have are unlikely to increase risks to a pregnancy. For more information, please see the MotherToBaby fact sheet Paternal Exposures at https://mothertobaby.org/fact-sheets/paternal-exposures-pregnancy/ .
Quoted from MotherToBaby Fact Sheets — Nitrofurantoin, published February 2024. MotherToBaby states its fact sheets should not take the place of medical care and advice from your healthcare providers.
Breastfeeding is a separate question — what LactMed says about nitrofurantoin
More guides for Nitrofurantoin
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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.