Drugs and chemicals in breast milk.

Most of the drugs present in the maternal circulation are transferred in varying degrees into breast milk. Not enough is yet known regarding the long- and short-term effects and safety of these drugs on the nursing infant. The final concentration of the drug in mothers milk depends on such factors as lipid solubility and the degree of ionization and protein-binding of the particular drug molecule. This paper is a somewhat detailed review of the drugs and chemicals which are currently known to have adverse effects on some breast-fed babies and those which are not currently considered hazardous to infants. Each type of drug e.g. anticonvulsants and anticoagulants is discussed separately. OCs (oral contraceptives) are not to be taken during the lactation period. OCs can cause a decrease in the milk supply and alterations in the composition of the milk. The longterm effects of OCs on infants are not yet known.