Is it okay to continue breastfeeding if a mother is starting on Keflex (cephalexin) 500mg four times a day (QID) for 7 days for mastitis?

Breastfeeding While Taking Cephalexin for Mastitis

Yes, it is absolutely safe to continue breastfeeding while taking cephalexin 500mg QID for mastitis. 1 The benefits of continuing breastfeeding during mastitis treatment significantly outweigh any potential risks to the infant.

Safety of Cephalexin During Breastfeeding

Cephalexin is considered compatible with breastfeeding based on multiple lines of evidence:

• According to FDA drug labeling, cephalexin is excreted in breast milk in small amounts, reaching a maximum level of 4 mcg/mL after a 500mg dose, and gradually disappears within 8 hours after administration 1
• The relative infant dose of cephalexin through breast milk is approximately 0.5% of the maternal dose 2, which is well below the 10% threshold generally considered safe for breastfeeding infants

Benefits of Continuing Breastfeeding with Mastitis

Continuing breastfeeding during mastitis treatment is actually recommended because:

1. Regular milk removal is a crucial part of mastitis treatment 3
2. Interrupting breastfeeding can worsen engorgement, potentially leading to blocked ducts and worsening the mastitis 3
3. Stopping breastfeeding may contribute to early cessation of breastfeeding altogether 3
4. The risk of necrotizing enterocolitis increases in premature infants if breast milk is temporarily replaced with formula 3

Treatment Approach for Mastitis

For optimal treatment of mastitis while breastfeeding:

1. Continue breastfeeding on the affected breast to ensure complete emptying
2. Complete the full course of cephalexin 500mg QID for 7 days to prevent recurrence
3. Use warm compresses before feeding to help with milk flow
4. Consider pain medication like ibuprofen or paracetamol, which are also compatible with breastfeeding 3

Potential Side Effects to Monitor

While cephalexin is considered safe during breastfeeding, be aware that:

• Some infants may experience mild gastrointestinal effects, particularly diarrhea 2
• If the infant develops significant diarrhea, consult with the pediatrician, but this is uncommon

Important Considerations

• Mastitis occurs in approximately 10% of breastfeeding mothers in the US 4
• Early and appropriate treatment of mastitis is essential to prevent complications like breast abscess 4
• Cephalexin is effective against Staphylococcus aureus, which is a common cause of mastitis 4

In conclusion, the evidence strongly supports continuing breastfeeding while taking cephalexin for mastitis. The benefits of maintaining breastfeeding far outweigh any minimal risks to the infant, and continued breastfeeding actually helps resolve the mastitis more quickly.