Is Keflex (cephalexin) safe to use during breastfeeding?

Keflex (Cephalexin) Safety During Breastfeeding

Keflex (cephalexin) is safe to use during breastfeeding as it transfers into breast milk in minimal amounts, with relative infant doses of only 0.5% of the maternal dose, well below the 10% threshold of concern.

Safety Profile in Breastfeeding

• Cephalexin is excreted in human breast milk but reaches maximum levels of only 4 mcg/mL within 4 hours after a 500 mg dose and disappears completely from milk within 8 hours after administration 1.
• The average concentration of cephalexin in breast milk is approximately 745 microg/L, corresponding to an absolute infant dose of 112 μg/kg/day and a relative infant dose of only 0.5% of the maternal dose 2.
• This relative infant dose is significantly below the notional 10% level of concern for infant exposure, making systemic effects in the breastfed infant highly unlikely 2.

Potential Concerns and Monitoring

• While systemic effects are unlikely, there is a possibility of local gastrointestinal effects in the breastfed infant, most notably diarrhea 2.
• Mothers should monitor their infants for signs of:
  • Diarrhea (particularly watery or bloody stools)
  • Poor feeding
  • Irritability
  • Changes in stool pattern 1, 2
• If these symptoms occur, healthcare providers should be contacted promptly 1.

Clinical Recommendations

• Cephalexin can be administered in relatively high oral doses without significant gastrointestinal irritation in the mother 3.
• Because it is absorbed high in the intestinal tract, it typically does not disturb the lower bowel flora 3.
• Most antibiotics, including cephalexin, can be used safely during breastfeeding at recommended doses 4.
• No dosage adjustment is necessary for breastfeeding women with normal renal function 3.

Special Considerations

• Caution should be exercised when cephalexin is administered to a nursing woman, but the benefits typically outweigh the risks 1.
• For women with impaired renal function, dosage adjustments may be necessary, as cephalexin is primarily cleared by the kidneys 3.
• If treating mastitis or breast infections in lactating women, clinicians should be particularly vigilant about monitoring for potential gastrointestinal effects in the breastfed infant 2.

Practical Advice

• Mothers can continue to breastfeed normally while taking cephalexin 2.
• There is no need to "pump and dump" or interrupt breastfeeding during cephalexin therapy 4.
• Taking cephalexin immediately after breastfeeding may help minimize infant exposure, although this is generally unnecessary given the low transfer rates 2.