Many drugs taken by a mother make their way into her milk. The important question is not whether the drug gets into milk, but whether the levels in
the milk are such that they will affect the baby.
Here are some of the factors that influence how much of a drug gets into a mother's milk and how
it affects her baby.
- While most drugs do pass into your milk, most appear in only minute amounts - usually
around one percent or less of the amount taken by the mother.
- The route of administration influences how fast the medication enters and clears from your
blood, and therefore your milk. For example, some medications come in both oral and
inhalant forms, which have different clearing times.
- It's better to use a short-acting medicine that is taken three or four times a day than to use a
long-acting, once-a-day form of the medication. . Although less convenient, short-acting
medications clear from your blood and milk faster. They're also easier for babies to
metabolize, so there is less risk of the drug accumulating in the infant's system.
- Consider the age of your baby. More caution is called for when giving medication to a
mother who is breastfeeding a premature or newborn infant ten times a day than when
prescribing medication for a woman breastfeeding a one-year-old four times a day. An infant
that feeds more frequently naturally gets more of the medicine, and the smaller size of the
younger infant means the drug will be more concentrated in the baby's body. . Also, the
liver and the kidneys of older infants are better able to metabolize and eliminate the drug.
- Most drugs taken by the mother are of less concern while breastfeeding than if she were
taking them during pregnancy. If a drug is safe to use during pregnancy, it is probably safe
during lactation. There is more reason to be concerned about the effects of a drug on a
growing fetus than on a fully developed infant.
- If there are concerns about possible effects on your baby, can the doctor monitor the baby
during the time you are taking the drug? This might involve checking levels of the drug in
your milk or the baby's blood, or watching carefully for changes in your baby's behavior.
- Be particularly cautious about taking more than one drug while breastfeeding. While each
drug taken separately may be listed in the safe category, together they may be unsafe (if not
for your baby, for you). Be sure to tell your doctor about any medications you are already
taking before he prescribes another. Pharmacists are often the most reliable source of
information on drug interactions.