Many medications and illegal drugs taken by a lactating mother are found in breast milk.  While most medications are greatly diluted by the processes of digestion and metabolism, some medications are concentrated in breast milk.  Infants, because of their small size, may be more sensitive to small doses of medications.  All mothers who have breastfeeding infants should discuss the use of any medication with their doctor.

Are medications taken by the mother found in breast milk?

Yes.  Most medications are diluted or greatly metabolized before entering the breastmilk so many medications are safe for breastfeeding mothers.  When the mother takes a medicine by mouth, it passes several steps before affecting a baby:

1. Passes through the mother's digestive system
2. Absorbed by the mother's bloodstream
3. Metabolized by the mother's liver
4. Diffuses into the breast milk
5. Passes through the infant's digestive system
6. Enters the infant's bloodstream
7. Metabolized by the infant's liver

In most cases, each of these steps reduces the potency of a medication before affecting the breastfeeding infant.

Are some medications found in high concentrations in breast milk?

Yes.  This is an important concept.  Some medications, especially medications that affect the brain, are concentrated in breast milk.  This means that breast milk may contain a higher concentration of the medication than the mother's blood.  Breast milk has a high fat content, and this fat helps some medications (i.e., lipophilic - fat-loving) absorb readily into breast milk where it is "trapped."  This is the same reason drugs like seizure medications enter the brain so well.  Some medications prefer the slightly more acidic breast milk when compared to the mother's blood.

If the dose of medication to the breastfed infant is so small, what is the danger?

Remember that infants are much smaller than the mother.  Even tiny doses of certain medications can have profound effects on an infant.

What about antibiotics?

Most antibiotics in the mother are safe for breastfeeding infants.  Perhaps the highest risk to the infant is that the antibiotics will kill the "good" bacteria in the infant's colon.  This can lead to severe diarrhea or even a severe systemic infection.

What about pain medicines?

Ibuprophen (i.e., Motrin or Advil) and acetaminophen (i.e., Tylenol) are generally considered safe for a mother to take while breastfeeding... but check with your doctor.  Stronger pain medicines like morphine, codeine, methadone and demerol have to potential to cause sedation and breathing difficulty in breastfeeding infants.  These medicines are sometimes used in breastfeeding mothers under the close supervision of a doctor.

What about decongestants?

Decongestants like pseudoephedrine (i.e., Sudafed) are NOT recommended for breastfeeding mothers.  These medicines can reduce the mother's production of breastmilk which could potentially cause dehydration or malnutrition in a breastfeeding infant.

How about caffeine?

A small amount of caffeine enters the breast milk after consumed by the mother.  While the dose is small, caffeine in breast milk stays in the infant's system longer than it would in an adult.  Small doses can cause jitteriness and stimulation in the infant.

How about alcohol?

Alcohol crosses into the breast milk.  The effects on the infant are dose-related, which means the more a mother drinks, the more likely it is to affect the infant.  Alcohol has also been shown to reduce breast milk production and infants are likely to drink less when alcohol is found in breast milk (possibly due to an unpleasant taste of the milk).  Mother's who must drink alcohol during breastfeeding should consider waiting one hour or more (per drink) before feeding the infant.  This allows the concentration of alcohol in breastmilk to decrease along with the decrease in blood alcohol level of the mother. 

Intoxication of any form (i.e., getting drunk or high) is potentially harmful to the mother and baby.  Intoxicated mothers who have "passed out" have unintentionally suffocated young infants.

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