Can I take nitrofurantoin while pregnant or breastfeeding?
A plain-words look at what the NHS, the US drug label and LactMed say about nitrofurantoin.
In short
Pregnancy: Nitrofurantoin can be taken in pregnancy, but it's generally recommended that you avoid it near the end of pregnancy, as there's a small chance of it causing problems with your baby's red blood cells.
Breastfeeding: You can usually take nitrofurantoin during breastfeeding if your baby is healthy, but speak to your doctor or pharmacist first.
Your doctor, midwife or pharmacist can help you decide.
What this means for you
Pregnancy
- Most babies won't have this problem, but if you're more than 28 weeks pregnant your doctor may recommend another antibiotic.
Breastfeeding
- Small amounts of nitrofurantoin reach breast milk, and side effects in your baby are unlikely.
- But it's best to take it for a short time only, and to talk to your doctor or pharmacist if you need it for more than a few weeks.
- It's important to get treatment if you have an infection, or if there's a risk of infections coming back.
- If your baby has any of the following, do not take nitrofurantoin while breastfeeding: jaundice (signs include yellowing of the skin and the whites of the eyes, which may be harder to see on brown or black skin, pale poo and dark pee), a very high level of a substance called bilirubin in the blood, or glucose-6-phosphate dehydrogenase (G6PD) deficiency, a rare condition affecting red blood cells.
- Side effects in breastfed babies from medicines their mother takes are very rare, but it's important to keep an eye on your baby whenever you take a medicine while breastfeeding.
When to get help
- Contact a healthcare professional or call 111 (NHS 111 in the UK) as soon as you can if your baby is feeding less well than normal or not gaining weight as you'd expect, is vomiting (being sick) or has diarrhoea, or has oral thrush (a fungal infection in the mouth).
- For symptoms not mentioned here, or if you're worried about your baby, you can also speak to any healthcare professional or call 111.
Talk to your doctor or pharmacist
This page is educational, not advice for your own situation. Talk to your doctor, midwife or pharmacist before you start, stop or change any medicine in pregnancy or while breastfeeding.
The details: what each source says
Nitrofurantoin in pregnancy
The NHS says
Nitrofurantoin can be taken in pregnancy, but it's generally recommended that you avoid it near the end of pregnancy, as there's a small chance of it causing problems with your baby's red blood cells.
Most babies won't have this problem, but if you're more than 28 weeks pregnant your doctor may recommend another antibiotic.
In our words, from the NHS page Nitrofurantoin (nhs.uk). Contains public sector information licensed under the Open Government Licence v3.0 (OGL v3.0). The NHS does not endorse this site.
What these words mean
- carcinogenic
- able to cause cancer
Definitions adapted from the NCI Dictionary of Cancer Terms (National Cancer Institute).
The US drug label says
Pregnancy: Teratogenic effects: Pregnancy Category B. Several reproduction studies have been performed in rabbits and rats at doses up to six times the human dose and have revealed no evidence of impaired fertility or harm to the fetus due to nitrofurantoin. In a single published study conducted in mice at 68 times the human dose (based on mg/kg administered to the dam), growth retardation and a low incidence of minor and common malformations were observed. However, at 25 times the human dose, fetal malformations were not observed; the relevance of these findings to humans is uncertain. There are, however, no adequate and well-controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed. Non-teratogenic effects: Nitrofurantoin has been shown in one published transplacental carcinogenicity study to induce lung papillary adenomas in the F1 generation mice at doses 19 times the human dose on a mg/kg basis. The relationship of this finding to potential human carcinogenesis is presently unknown.
Prescribing label, section “Pregnancy” (opening excerpt): NITROFURANTOIN (oral), REMEDYREPACK INC. Read the full section on DailyMed. Quoted verbatim; US labels are written for US prescribers and patients.
More on nitrofurantoin in pregnancy: Bumps (Best Use of Medicines in Pregnancy) leaflet (external site).
Nitrofurantoin while breastfeeding
The NHS says
You can usually take nitrofurantoin during breastfeeding if your baby is healthy, but speak to your doctor or pharmacist first.
Small amounts of nitrofurantoin reach breast milk, and side effects in your baby are unlikely. But it's best to take it for a short time only, and to talk to your doctor or pharmacist if you need it for more than a few weeks. It's important to get treatment if you have an infection, or if there's a risk of infections coming back.
If your baby has any of the following, do not take nitrofurantoin while breastfeeding: jaundice (signs include yellowing of the skin and the whites of the eyes, which may be harder to see on brown or black skin, pale poo and dark pee), a very high level of a substance called bilirubin in the blood, or glucose-6-phosphate dehydrogenase (G6PD) deficiency, a rare condition affecting red blood cells.
Side effects in breastfed babies from medicines their mother takes are very rare, but it's important to keep an eye on your baby whenever you take a medicine while breastfeeding.
Contact a healthcare professional or call 111 (NHS 111 in the UK) as soon as you can if your baby is feeding less well than normal or not gaining weight as you'd expect, is vomiting (being sick) or has diarrhoea, or has oral thrush (a fungal infection in the mouth).
For symptoms not mentioned here, or if you're worried about your baby, you can also speak to any healthcare professional or call 111.
In our words, from the NHS page Nitrofurantoin (nhs.uk). Contains public sector information licensed under the Open Government Licence v3.0 (OGL v3.0). The NHS does not endorse this site.
LactMed says
Administration of nitrofurantoin directly to infants under 1 month of age and in those with glucose-6-phosphate dehydrogenase (G6PD) deficiency is contraindicated because of potential hemolysis in these infants. However, the time of greatest risk for hemolysis in fullterm newborns without G6PD deficiency might be as short as 8 days after birth.[1] Nitrofurantoin doses in milk are low and it can be used while breastfeeding older infants, but alternate drugs are preferred in mothers of infants under 8 days of age, or infants with G6PD deficiency of any age. Observe infants for possible diarrhea.
“Summary of Use during Lactation”, LactMed record “Nitrofurantoin” (LM202), quoted verbatim. Everything LactMed reports about Nitrofurantoin while breastfeeding.
What these words mean
- contraindication
- a reason not to use a treatment, because it may be harmful
Definitions adapted from the NCI Dictionary of Cancer Terms (National Cancer Institute).
The US prescribing label says
Nursing Mothers: Nitrofurantoin has been detected in human breast milk in trace amounts. Because of the potential for serious adverse reactions from nitrofurantoin in nursing infants under one month of age, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother (see CONTRAINDICATIONS ).
Prescribing label, section “Nursing Mothers”: NITROFURANTOIN (oral), REMEDYREPACK INC. Label on DailyMed. Quoted verbatim; US labels are written for US prescribers and patients.
Other names
UK brand names (per the NHS): Macrobid.
Sources
- NHS, Nitrofurantoin (nhs.uk), page last reviewed 6 January 2026. Paraphrased. Contains public sector information licensed under the Open Government Licence v3.0.
- US drug label: NITROFURANTOIN (oral), REMEDYREPACK INC., human prescription drug, label effective 1 September 2026, set ID 87505f8f-2056-4e55-adf5-5b7309081d7c. DailyMed (National Library of Medicine). Public domain; quoted verbatim.
- Drugs and Lactation Database (LactMed), National Institute of Child Health and Human Development (NICHD), via NCBI Bookshelf, record “Nitrofurantoin” (LM202), bulk release of 22 September 2026. LactMed on NCBI Bookshelf. Public domain; quoted verbatim. LactMed is a registered trademark of the U.S. Department of Health and Human Services.
- Bumps (Best Use of Medicines in Pregnancy), UK Teratology Information Service: Bumps (Best Use of Medicines in Pregnancy) leaflet. Linked, not reproduced.
Sources checked 26 September 2026. How we source and check every page.
Educational summary of named sources, not medical advice.