Q&A: Safe antibiotics for nursing moms?

My doctor recommended I not take an antibiotic for an infection I developed because I’m nursing and it may harm my baby. Are any antibiotics safe when nursing? —Y.Y., Colrain, Mass.

Some appear safer than others, though the risks haven’t been well studied. There’s concern that ingesting antibiotics through breast milk may cause infants to develop diarrhea, nutritional deficiencies, or other problems. But the amount of antibiotic that passes into breast milk varies by drug, so you can limit your baby’s exposure by using the ones least likely to leach.

The safest appear to be the cephalosporins, such as cefaclor (Ceclor and generic), cephalexin (Keflex
and generic), or cefdinir (Omnicef); macrolides, such as clarithromycin (Biaxin and generic), azithromycin (Zithromax and generic), or erythromycin (E-Mycin and generic); and penicillins,
such as amoxicillin, ampicillin, and oxacillin. Antibiotics to avoid include metronidazole (Flagyl and generic); quinolones, such as ciprofloxacin (Cipro and generic); and tetracyclines, such as
doxycycline (Vibramycin and generic) or minocycline (Minocin and generic).

Taking medication right after nursing may also minimize exposure.