What's In Your Breast Milk?

Many medicines and drinks—even certain foods—can affect your baby if you're nursing. Here's how to make sure you both stay safe and healthy.

Boosting breastmilk supply mom breastfeeding baby
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Demetria Santillan, of Tucson, Arizona, had been nursing her son, Ramiro, for nearly twelve months when she developed a urinary-tract infection. Her doctor said she needed medication and would have to stop breast-feeding for a week; another doctor agreed. Santillan, who didn't want to stop nursing, consulted a third physician. "It took some legwork, but he found a safe drug," she recalls.

Anything you ingest while nursing might end up in your breast milk—and affect your baby. But this does not automatically mean you have to wean if you need to take medication.

In fact, you seldom even have to forgo small indulgences such as coffee. "The question is how much of a substance is in your breast milk, how much the infant consumes, and whether he metabolizes or eliminates it efficiently," says Patrick McNamara, Ph.D., a professor of pharmaceutical sciences at the University of Kentucky College of Pharmacy, in Lexington. There are steps you can take help keep your breast milk pure -- the first is to be informed.

Rx for Safety

The Food and Drug Administration does not mandate testing the safety of medications on lactating women. However, this doesn't necessarily mean you must forgo essential drugs. While Lauren Picker, of New York City, was nursing, she refused to take pain relievers for a migraine. Finally, a nurse practitioner told her that it was safe to take Tylenol with codeine.

Picker was lucky; doctors aren't always aware of the many pharmaceutical options available to lactating women. The problem, explains Lawrence M. Gartner, M.D., a professor emeritus of pediatrics and obstetrics/gynecology from the University of Chicago, stems partly from doctors' information sources. "They tend to look up drugs in the Physicians' Desk Reference," he notes. This guide, created by the pharmaceutical industry, recommends almost no medication for nursing mothers. "Drug companies would have to do extensive research to get the FDA to approve drugs specifically for lactating mothers, which is prohibitively expensive," Dr. Gartner says. In reality, scientists are finding that many drugs are safe (see list below).

Generally, medications are thought to be acceptable for breast-feeding women and their babies if they are commonly prescribed to infants, are considered safe during pregnancy, or are taken topically or by injection. Still, consult a doctor before using any drug.

Raise a Glass Cautiously

One beer or glass of wine probably won't cause harm, but think twice before drinking more heavily. The alcohol will accumulate in your baby's bloodstream, causing sleepiness and other changes—or even intoxication, Dr. Gartner warns. If you're going out for cocktails, pump and freeze milk beforehand, then pump and dump milk afterward to keep up your supply. You can usually resume breast-feeding by morning.

People often say that sipping wine before nursing helps bring down your milk, but it actually has the opposite effect. Alcohol reduces the body's levels of prolactin, the hormone that stimulates milk production. "A baby will suckle more avidly because he has to work harder, but still gets less milk," says Carol Huotari, a board-certified lactation consultant and manager of the Center for Breastfeeding Information at La Leche League International, in Schaumburg, Illinois. Regular drinking can also lead to reduced weight gain in infants.

Smoking Out Trouble

Nicotine is also passed on to babies via breast milk and can cause diarrhea, vomiting, or fussiness. In one study, 40 percent of babies breast-fed by smokers were colicky, versus 26 percent of infants nursed by nonsmokers.

Like alcohol, nicotine seems to reduce prolactin levels and milk supply. "Some mothers who smoke and breast-feed have babies who don't gain weight well," Huotari says. If you must smoke, don't do it near the baby. Nicotine lev-els peak in milk about 30 minutes to an hour after you smoke.

Ease Your Caffeine Jitters

A cup of coffee with breakfast, even another with lunch, probably won't affect your nursing infant. But if you down a couple of tall lattes every morning and sip cola all afternoon, your baby may become restless and irritable or even have trouble sleeping, especially if she's a newborn. "The less mature the baby, the longer it takes her to clear the caffeine out of her system," says Ruth A. Lawrence, M.D., a professor of pediatrics, obstetrics, and gy-necology at the University of Rochester Medical Center, in New York. Limit yourself to two cups of coffee in a 24-hour period, and avoid other drinks that contain caffeine.

Food for Thought

Do you need to monitor other aspects of your diet? Some experts recommend avoiding excessive amounts of artificial sweeteners. Aspartame-sweetened drinks are a better choice than those made with saccharin, which is secreted in breast milk in greater amounts.

Many nursing women avoid foods like garlic and broccoli because they make some infants gassy, but every baby reacts differently, so there are no universal "bad foods." On the other hand, some breast-fed infants do demonstrate sensitivities and may become fussy or develop a rash if their mother eats a certain food. (Common culprits include dairy products, broccoli, cauliflower, and oatmeal.) If your child seems to be reacting to something in your diet, keeping a food diary can help you identify the cause. Try eliminating the suspect food for a week to ten days and, with a little bit of luck, you'll see your baby's symptoms start to wane.

Lastly, there has been some indication that eating peanut products while you're nursing may sensitize some children to them, triggering a dangerous allergy later. The evidence is still circumstantial, but you may wish to avoid peanuts until you wean.

Which Drugs Are Safe?

Which drugs are safe for lactating women and their babies? Here's what the American Academy of Pediatrics says about some common medications.

Usually Safe


Most nonsteroidal anti-inflammatory medications, including ibuprofen



Thyroid medications



Most antihistamines

Use With Caution


Antianxiety drugs (like Xanax and Valium)


Recreational drugs (like marijuana and cocaine)

Radioactive drugs (such as radioactive iodine, used to treat thyroid disorders)

Anticancer drugs

Ergotamine (for migraines)



For more information, try these resources:

  • The Website of the American Academy of Pediatrics (www.aap.org).
  • The FDA's Website (www.fda.gov).
  • Medications and Mothers' Milk, by Thomas W. Hale, Ph.D. (Pharmasoft Medical Publishing, 2000)
  • Breastfeeding: A Guide for the Medical Profession, by Ruth A. Lawrence, M.D., and Robert M. Lawrence, M.D. (Mosby -- Year Book, 1998)
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