Maternal use of oral opioids during breastfeeding can cause infant drowsiness, which may progress to rare but severe central nervous system depression. Like codeine, pharmacogenetics probably plays a role in the extent of central nervous system depression with dihydrocodeine. Newborn infants seem to be particularly sensitive to the effects of even small dosages of narcotic analgesics. Dihydrocodeine possibly caused severe respiratory depression in one newborn infant whose mother was taking the drug for cough. If dihydrocodeine is required by the mother of a newborn, it is not a reason to discontinue breastfeeding; however, once the mother's milk comes in, it is best to provide pain control with a nonnarcotic analgesic and limit maternal intake of dihydrocodeine to 2 to 3 days at a low dosage with close infant monitoring. If the baby shows signs of increased sleepiness (more than usual), difficulty breastfeeding, breathing difficulties, or limpness, a physician should be contacted immediately. Because there is little published experience with dihydrocodeine during breastfeeding, an alternate drug may be preferred, especially while nursing a newborn or preterm infant.