Nitrofurantoin (Macrolid®)

Last Update: 22 May 2025

Medication

Table of content

1. What is it? 2. What are the risks according to research? 3. Breastfeeding/ chestfeeding 4. What about fathers and sperm donors? 5. Key points

Welcome to our fact sheet on nitrofurantoin during pregnancy and breastfeeding/chestfeeding. This information is based on available published literature. It should not take the place of medical care and advice from your healthcare provider.

The HEALTHY PREGNANCY HUB team is collaborating with MotherToBaby to share information on this topic. The original version is available here (February 2024).

Serene, our chatbot, can also answer your questions about medications during pregnancy.

Please note that this fact sheet is based on United States information and has been adapted for Canada, with a review by our Canadian experts. Minor differences may exist between the two countries. Always consult your healthcare professional for information tailored to your situation.

1. What is nitrofurantoin?

Nitrofurantoin is an antibacterial medication that has been used to treat urinary tract infections (UTIs). Some brand names are Macrobid®, Macrodantin®, and Furadantin®.

Sometimes when people find out they are pregnant, they think about changing how they take their medication, or stopping their medication altogether. However, it is important to talk with your healthcare providers before making any changes to how you take your medication. Your healthcare provider can talk with you about using nitrofurantoin and what treatment is best for you.

The American College of Obstetricians and Gynecologists (ACOG) states that it is “reasonable to offer” nitrofurantoin in the first trimester when other medication is not available. ACOG also states that the use of nitrofurantoin in the second and third trimester has been considered a first-line treatment for UTIs.

The product label for nitrofurantoin recommends that individuals who are near the end of their pregnancy (38 to 42 weeks gestation) or are otherwise close to delivery should not use this medication.

2. What does research say about the risks during pregnancy?

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, pregnant individuals 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, pregnant individuals 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.

3. Breastfeeding/ chestfeeding while taking nitrofurantoin

Nitrofurantoin gets into breast milk in small amounts. In a report on 6 individuals taking nitrofurantoin while breastfeeding or chestfeeding, 2 noted that their children had diarrhea. When any antibiotic is taken during breastfeeding or chestfeeding, babies can be watched for diarrhea or rash.

The product label for nitrofurantoin recommends that people who are breastfeeding or chestfeeding should not use this medication when infants are less than 1 month old or if the nursing infant has a diagnosis of glucose-6-phosphate dehydrogenase deficiency (G6PD) due to the risk of hemolytic anemia (breakdown of red blood cells). However, the benefits of treating your condition, as well as the benefits of breastfeeding or chestfeeding, may outweigh possible risks. Use of nitrofurantoin while breastfeeding or chestfeeding an older infant without G6PD is unlikely to cause side effects. Your healthcare providers can talk with you about using nitrofurantoin and what treatment is best for you while you are nursing. Be sure to talk to your healthcare provider about all your breastfeedin or chestfeeding questions.

4. What about fathers and sperm donors?

If a male takes nitrofurantoin, could it affect fertility or increase the chance of birth defects?

When nitrofurantoin was given to male 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 a 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 a male’s 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 here.

Key points

Nitrofurantoin (Macrobid®, Macrodantin®, Furadantin®) is an antibiotic prescribed to treat urinary tract infections.
Most studies have not found a link between this medication and an increased risk of miscarriage or birth defects. It is unknown whether it may increase the risk of other pregnancy complications.
Nitrofurantoin can be used during pregnancy, but the manufacturer advises against using it late in pregnancy (between 38 and 42 weeks) due to a rare risk of anemia in the newborn.
Nitrofurantoin passes into breast milk in small amounts. It is generally considered safe while breastfeeding, unless the baby is under one month old or has a rare condition called G6PD deficiency.
Always talk to your healthcare provider to discuss the benefits and risks of this treatment during pregnancy or breastfeeding.

References

Please click here to view references.

Disclaimer

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