Can you take nitrofurantoin while breastfeeding?

What LactMed would consider instead

LactMed ends this record by naming the drugs it would consider in place of nitrofurantoin. Whether any of them fits depends on what you are treating — this is the database’s list, not a recommendation from us.

• Ciprofloxacin
• Levofloxacin
• Trimethoprim

How much nitrofurantoin gets into breastmilk

The time of the peak amounts in milk depends on the food taken with the drug and the dosage form of the drug. Rapid-release capsules of nitrofurantoin macrocrystals reach their peak milk levels either 1 to 2 hours after the dose with food or 4 hours after a high-fat meal. The sustained-release product (Macrobid) has not been studied, but probably has a delayed peak milk time that would be difficult to predict in an individual mother.

Maternal Levels. In one early report, random samples of milk from several women in the first few days postpartum who were receiving 100 mg orally 4 times daily were tested for nitrofurantoin. Nitrofurantoin was undetectable (<2 mg/L) in 20 samples measured.

A second study found milk levels ranging from 0 to 0.5 mg/L in 4 women (time postpartum not stated) 2 hours after a single dose of 200 mg of nitrofurantoin was given orally during therapy with 100 mg 4 times a day. In 5 others receiving 100 mg orally 4 times daily, no drug was detected in milk levels (assay limit not stated).

Six women who were 3 to 6 days postpartum were given 50 or 100 mg of nitrofurantoin macrocrystals orally 3 times a day. Nitrofurantoin was undetectable (<10 mcg/L) in all women before the first dose of the second day of administration with breakfast (fat content not stated). Peak milk levels occurred 1 to 2 hours after the dose. Mothers taking the 50 mg dose had an average of 0.49 mg/L (range 0.2 to 0.7 mg/L) in milk 3 hours after the dose and those given 100 mg had milk levels of 1.19 mg/L (range 0.62 to 2.22 mg/L) in milk at 3 hours. The authors calculated that between 0.06 and 0.28% of a dose was excreted into milk during the 6 hours after a dose.

Four women who were 8 to 26 weeks postpartum received a single 100 mg dose of nitrofurantoin macrocrystals orally with a high-fat meal. Under these conditions, peak milk levels occurred 4 to 6 hours after the dose. Peak levels averaged 2.7 mg/L (range 2.2 to 3.2 mg/L). Milk levels were higher than serum levels and much higher than predicted at all times, indicating active transport into milk. Nevertheless, an exclusively breastfed infant would receive only 0.2 mg/kg daily or about 6% of the weight-adjusted maternal dosage.

Infant Levels. Relevant published information was not found as of the revision date.

What has been seen in breastfed infants

In a prospective follow-up study, 6 nursing mothers reported taking nitrofurantoin (dosage and dosage form not specified). Two mothers reported diarrhea in their infants. No rashes or candidiasis were reported among the exposed infants.

Effects on milk supply

In a prospective follow-up study, 1 of 6 nursing mothers who took nitrofurantoin (dosage unspecified) reported a decrease in milk supply. It is not known if there was a causal relationship.