Can I take Flagyl (metronidazole) while breastfeeding?

Metronidazole (Flagyl) During Breastfeeding

Metronidazole (Flagyl) is possibly safe during breastfeeding, but temporary interruption of breastfeeding for 12-24 hours after taking a dose is recommended to minimize infant exposure.

Safety Assessment

Metronidazole transfers into breast milk at concentrations similar to those found in maternal plasma. According to the European Respiratory Society guidelines, metronidazole is classified as "possibly safe" during breastfeeding 1. However, the FDA drug label notes that "because of the potential for tumorigenicity shown for metronidazole in mouse and rat studies, 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" 2.

Recommendations for Different Dosing Regimens

Single-Dose Treatment (2g)

• If you need to take a single 2g dose of metronidazole:
  • Take the dose immediately after breastfeeding
  • Pump and discard breast milk for 12-24 hours after taking the medication 3
  • Resume breastfeeding after this period when drug levels are significantly reduced

Multiple-Dose Treatment

• For standard treatment regimens (e.g., 400-500mg three times daily):
  • Metronidazole is excreted in breast milk at concentrations similar to plasma levels 4
  • Infant plasma levels reach approximately 15% of maternal plasma levels 5
  • Studies have not shown significant adverse effects in breastfed infants 4

Potential Concerns and Monitoring

While metronidazole in breast milk has not been associated with serious adverse effects in most infants, there are some theoretical concerns:

• Potential for altered taste of breast milk (metallic taste)
• Possible infant gastrointestinal disturbances
• Theoretical concern about long-term effects (though not documented in humans)

Alternative Approaches

If you are concerned about taking metronidazole while breastfeeding, discuss these options with your healthcare provider:

1. Temporary interruption of breastfeeding with pumping and discarding milk during treatment
2. Consideration of alternative antibiotics if appropriate for your condition
3. Delaying treatment if clinically appropriate and your condition is not severe

Bottom Line

The evidence suggests that metronidazole use during breastfeeding poses minimal risk to healthy, full-term infants, especially with short-term use. However, to minimize exposure, consider temporarily interrupting breastfeeding for 12-24 hours after taking a dose, particularly with the single-dose (2g) regimen.

If you must continue breastfeeding without interruption while taking metronidazole, the available evidence indicates this is likely safe for short-term use, as studies have not demonstrated significant adverse effects in breastfed infants 6.