Can you take nalidixic acid while breastfeeding?
What LactMed says
The National Library of Medicine’s own summary, quoted in full. We do not write a verdict of our own on this question, and we do not compress theirs into a label.
Limited information indicates that maternal doses of nalidixic acid up to 2 grams daily produce low levels in milk and would usually not be expected to cause any adverse effects in breastfed infants with monitoring of the infant for possible effects on the gastrointestinal flora, such as diarrhea or candidiasis (thrush, diaper rash). Nalidixic acid should be avoided while breastfeeding a glucose-6-phosphate dehydrogenase (G6PD) deficient infant. Other agents are preferred, especially while nursing a newborn or preterm infant.
Quoted from Nalidixic Acid — Drugs and Lactation Database (LactMed®), National Institute of Child Health and Human Development, revised July 15, 2024.
What LactMed would consider instead
LactMed ends this record by naming the drugs it would consider in place of nalidixic acid. Whether any of them fits depends on what you are treating — this is the database’s list, not a recommendation from us.
How much nalidixic acid gets into breastmilk
Maternal Levels. One paper reported old, unpublished data obtained from the manufacturer in which a breastmilk concentration of 2 mg/L was found at an unspecified time in 4 women taking nalidixic acid 1 gram orally 4 times daily.
Thirteen lactating women were given 2 grams of nalidixic acid as a single dose between the third and eighth day postpartum. The average concentration of nalidixic acid in milk during the first four-hour collection period was 0.64 mg/L (range 0.3 to 1.1 mg/L); concentration in milk from other collection periods were as follows: 0.43 mg/L at 4 to 7 hours; 0.2 mg/L at 7 to 10.5 hours; 0.1 mg/L at 10.5 to 16 hours and 0.02 mg/L at 16 to 24 hours after the dose. Using the peak milk level data from this study, the authors estimated that an exclusively breastfed infant would receive a maximum of 300 mcg daily with this maternal dosage regimen, or less than 0.3% of an infant dose.
Infant Levels. Relevant published information was not found as of the revision date.
What has been seen in breastfed infants
Decreased weight gain, pallor, jaundice occurred in a 16-day-old infant probably caused by hemolytic anemia induced by maternal use of nalidixic acid orally 1 gram four times daily and amobarbital 65 mg orally three times daily. The infant developed jaundice, hyperbilirubinemia, reticulocytosis, eosinophilia, Heinz bodies and other signs of hemolysis 7 days after its mother was started on nalidixic acid. No G-6-PD deficiency or hemoglobin Zurich could be demonstrated.
Effects on milk supply
Relevant published information was not found as of the revision date.
Frequently asked questions
Can you take nalidixic acid while breastfeeding?
What the NIH's Drugs and Lactation Database says about Nalidixic Acid while breastfeeding — quoted in full. The full record is quoted on this page, and the decision is one to make with the person who prescribed it — LactMed itself states it is not a substitute for professional judgement.
What can I take instead of nalidixic acid while breastfeeding?
LactMed lists Ciprofloxacin, Levofloxacin, Nitrofurantoin, Trimethoprim as alternate drugs to consider. That is the database's own list for this drug — whether any of them suits you depends on what you are treating.
Does nalidixic acid pass into breastmilk?
LactMed's measured drug levels for nalidixic acid are quoted in full on this page, under "How much gets into breastmilk".
Do I need to pump and dump after taking nalidixic acid?
LactMed does not frame its records that way — it reports measured drug levels in milk and what has been observed in breastfed infants, which is what this page quotes. "Pump and dump" advice for a specific drug and dose should come from your clinician or a pharmacist, not from a general rule.
More on nalidixic acid
LactMed states that the information it presents is not a substitute for professional judgement, and that you should consult your healthcare provider for breastfeeding advice related to your particular situation. Nothing on this page is medical advice.