Penicillins and cephalosporins are the antibiotics of choice during breast-feeding. Wherever possible, it is preferable to use antibiotics which have been used clinically for longer, for example the second generation cephalosporins. Where necessary, other antibiotics can be chosen, but they should always be used at the lowest possible dose.
Drug exposure to the infant may be minimised by the mother taking the medication just after she has breastfed the infant or just before the infant is due to have its longest sleep period.
Although the concentrations of penicillins and cephalosporins in breast milk are too low to have a bactericidal effect in the infant and too low to cause systemic side-effects, the infant may still experience adverse effects by alteration of the oral and gut flora. This may theoretically lead to oral candida infections and diarrhoea.
If an infant has been sensitised to a particular antibiotic in utero, exposure to the antibiotic via breast milk is likely to cause an allergic reaction, no matter how low the breast milk concentration.
Therefore, although penicillins and cephalosporins are considered compatible with breastfeeding, the infant should still be monitored for adverse effects.