Not necessarily true. The exposure of the breastfed infant to medications in milk is usually 10 or more times lower than fetal exposure to the same drug in pregnancy. Furthermore, concerns about teratogenicity are nonexistent during lactation. Also, the old FDA categories (A, B, C, D, X) applied only to pregnancy and have nothing to do with lactation. New drug labeling has been implemented by the Food and Drug Administration that stresses the importance of breastmilk for the baby.

Not true. The phrase “concentrated in milk” usually refers to the concentration in milk being higher than in the mother’s bloodstream. Another way to express this is that a drug has a milk-to-plasma (M/P) concentration ratio >1. What is important is how much drug an infant receives during a day and how this compares to the infant dose of the drug. The M/P ratio does not accurately reflect these values.^1–3

Not true. Over time, a drug in breastmilk will return to the mother’s bloodstream and be eliminated by the mother. This occurs when the mother eliminates the drug from the bloodstream and the concentration in milk becomes higher than in the blood. This situation is similar to what occurs when a person drinks alcohol. Some alcohol goes into the brain and causes effects, but over time it leaves and is eliminated as the person metabolizes the alcohol.

Not true. Pumping milk from the breast does not hasten the overall elimination from the mother’s body, because only a small fraction of the drug in the mother’s body is in her breastmilk. After pumping, the drug returns to the milk from the mother’s bloodstream to about the same level in milk as prior to pumping.

Not true. Most side effects that have been reported in breastfed infants have been in first 1-2 months after birth. While some drugs should be avoided in newborns, older infants usually tolerate the amounts in milk well unless they are extremely toxic, such as cytotoxic cancer chemotherapy and some central nervous system depressants. Older infants metabolize and eliminate drugs much better than neonates. Infant age is one of the most important factors in determining a drug’s safety during breastfeeding.

Not necessarily. Most drugs applied to the skin are poorly absorbed into the mother’s bloodstream, so the amounts that get into milk are very low. One exception to this rule is the use of iodine or povidone iodine on large skin surfaces or on mucous membranes. Enough iodine can be absorbed and excreted into the mother’s milk to suppress the infant’s thyroid. Chlorhexidine is an alternative antiseptic that does not affect the thyroid.

When a drug in a cream or ointment is applied on or near the mother’s nipple where the baby can take the drug directly into the mouth, the infant can receive a fairly large dose of the drug. Care also needs to be used with very potent drugs applied to the skin where the infant might have skin-to-skin contact with the mother. Simply covering these areas so they don’t come into contact with the infant is sufficient.

Not true. Just like the drugs applied to the skin discussed above, these products are not absorbed well into the mother’s body. No special precautions are needed after the use of hair products by the mother.