Is Bactrim (sulfamethoxazole/trimethoprim) safe to use during lactation?

Safety of Bactrim (Sulfamethoxazole/Trimethoprim) During Lactation

Bactrim (sulfamethoxazole/trimethoprim) should be used with caution during lactation and is considered possibly safe only in healthy term babies; it should be avoided in infants who are glucose-6-phosphate dehydrogenase deficient, jaundiced, or premature. 1

Risk Assessment

• Bactrim is excreted in breast milk in small amounts (approximately 2-5% of the recommended daily dose for infants over 2 months of age) 2
• The CDC contraindicates Bactrim in nursing mothers with infants less than 2 months of age due to the risk of kernicterus (bilirubin-induced brain damage) 3
• Bactrim is specifically contraindicated in:
  • Premature infants 1
  • Jaundiced infants 2
  • Infants with glucose-6-phosphate dehydrogenase deficiency 1
  • Infants younger than 2 months of age 2

Potential Adverse Effects

• Sulfonamide component may cause:
  • Hyperbilirubinemia in neonates due to displacement of bilirubin from plasma proteins 1
  • Hemolytic anemia, particularly in G6PD-deficient infants 1
• Other potential concerns include:
  • Alteration of infant intestinal flora 1
  • Potential for false-negative cultures if the infant develops a febrile illness 1
  • Theoretical risk of kernicterus in susceptible infants 3, 2

Alternative Antibiotics for Lactating Women

If Bactrim is contraindicated or if the infant has risk factors, consider these safer alternatives:

• Penicillins and aminopenicillins (e.g., amoxicillin) - considered compatible with breastfeeding 1, 4
• Cephalosporins - considered compatible with breastfeeding 1, 4
• Macrolides (e.g., azithromycin) - probably safe, though there is a very low risk of hypertrophic pyloric stenosis if used during the first 13 days of breastfeeding 1, 4

Clinical Decision Algorithm

1. Assess infant risk factors:

   • Is the infant less than 2 months old? → Avoid Bactrim 2
   • Does the infant have jaundice? → Avoid Bactrim 2
   • Does the infant have G6PD deficiency? → Avoid Bactrim 1
   • Is the infant premature? → Avoid Bactrim 1

2. If no risk factors are present:

   • Bactrim can be used with monitoring of the infant for jaundice, rash, or diarrhea 5
   • Consider shorter treatment courses when possible 4

3. If risk factors are present:

   • Select an alternative antibiotic based on the infection being treated 4
   • Monitor infant closely if Bactrim must be used due to maternal indication with no suitable alternatives 5

Special Considerations

• The safety profile of Bactrim in lactation is better established than some newer antibiotics like linezolid, daptomycin, or tigecycline 5
• If Bactrim is required for maternal treatment of MRSA or other resistant infections, the benefits to the mother may outweigh the potential risks to the infant, particularly with close monitoring 5
• When treating urinary tract infections in lactating women, trimethoprim alone might be considered as an alternative with potentially fewer risks than the combination product 6