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Medications and the Breastfeeding Mom

Nationwide, the rate of breastfeeding has increased from 22% in 1972 to over 70% now.  As much as 99% of moms will be exposed to different medications while they are breastfeeding.  For these reasons, it is important to know how medications can affect breast milk.  Some healthcare providers will recommend a mother stop breastfeeding while on any medications.  However, in most cases, this is not necessary.  Interruption of breastfeeding may be difficult or even harmful for a mother and baby, so an individualized approach is better.

Communication with your healthcare provider is essential. If they know your goals for breastfeeding, they can usually choose a medication that allows for safe continuation.  In the rare circumstance when a medication is considered harmful to a baby and no alternative/safer drug can be substituted, the mother may be able to temporarily “pump and dump” her milk until the medication clears her milk. This is extremely rare.

The following are general guidelines only and are not meant to substitute for specific advice from a healthcare provider.  Every mother is unique and she should look for help from someone knowledgeable about her particular case as needed.

Drug penetration into Breast Milk

Many drugs may enter the breastmilk.  The amount depends on many factors and will vary greatly from drug to drug. Therefore, it may be important for your health care provider to look up the drug in a current textbook that specifically gives them this information.  If your health care provider does not have that information readily available, you may have to call another source and/or consult with your pharmacist or the baby’s care provider.  Many hospital nurseries, local La Leche League chapters, OB, pediatric, and WIC offices have up-to-date textbooks on their shelves, which can help, provide the information specific to the medication in question. They will usually be glad to share that information with the provider writing the prescription or the mother herself. A board-certified lactation consultant is also a good source of information that you or your healthcare provider can consult with.

Although there can be great variation, studies show that overall the nursing baby’s dose can often be as little as 1% of the mother’s dose.  This means if the mother is taking a 100 mg dose, the amount in the milk is 1 mg.  Drugs do not enter the breast milk directly from the mother’s blood.  It enters the milk indirectly through the mothers’ breast tissue.  During the first two weeks postpartum, medications may reach their highest concentration in the milk.  At this time, the infants’ digestive system is not well developed and the infant may absorb higher amounts of the drugs.  Therefore, more caution is usually needed with newborns than with older babies. Premature babies have a less mature gut and perhaps other medical problems.  Therefore, even more caution may be necessary with these babies. Your baby’s healthcare provider can give you advice based on your individual baby’s needs.

The amount of the drug in the milk will follow the amount of the drug in the mom’s blood.  As the level of medicine gets higher in the blood, it gets higher in the milk.  This is important to know because the mom may not want to breastfeed when the drug is at the peak in the blood.  If she can wait until the level of drug drops in the blood, she will expose her baby to a lower amount of the drug in her milk.  This works well for short acting drugs (taken every few hours) such as asthma “rescue” inhalers, penicillin, and many types of pain relievers.  It can be a good idea to breast feed right before taking the drug, then hopefully at the next feeding time (in 2 – 4 hours) the blood level of the drug will be lower.

Timing the breastfeeding around the dose may not be as useful or as important for longer acting drugs (taken only once or twice a day). For these, the blood levels are more stable for a longer period of time.  However, the blood and milk levels may be generally lower (overall) for long acting drugs, so it may not be something you need to work around.

The Effects of Drugs on Lactation

There are drugs that can decrease the amount of milk produced by a breastfeeding mom.  A decrease in milk production can have a direct effect on the baby’s growth and weight gain.  One common drug that can reduce the milk supply is the traditional or “combined” birth control pill.  If “the pill” contains estrogen, it is highly likely that it will decrease the amount of milk produced.  See the section below on “Breastfeeding Friendly Birth Control”.

Another common type of medication that can “dry up” milk supply are some cold and allergy remedies, such as antihistamines and decongestants.  In general, if it dries up your nose, it may tend to dry up your milk.  Sometimes these medications can be used for short-term relief - such as a few times at night so you can get some rest when sick.  Just be sure you take in plenty of water and continue to nurse “on cue” (when the baby seems hungry) and this will help protect your milk supply.  In general, however, other “home remedies” such as hot liquids (tea or soup), steam inhalation (a nice warm shower), non-medicated saltwater nose spray or drops, or use of “vaporous” cough drops or back rubs may be tried first for comfort. These will not disrupt breastfeeding. If you need to use decongestants or antihistamines on a regular basis to control allergies, you might want to talk to your health care provider about using some steroidal nasal spray to control your symptoms.  Very little of this is absorbed into your system and would not have a “drying effect” on your milk supply.

Types of Medications and Their Safety

Breastfeeding Friendly Birth Control: Hormonal methods of birth control are best put off until the milk supply is well-established, generally considered 6 weeks after delivery. Some birth control pills, the “patches”, and the “ring” all contain estrogen, therefore are best avoided if there is another choice that will work for the mother.  A special progestin-only “mini” pill does not affect the milk production.  If a combination (estrogen-containing) pill must be used, the “low-dose” combination would be preferred.  No study has shown that exposure to female hormones (estrogen) via mother’s milk is harmful to male infants. 
Depo-Provera birth control shots can be used with breastfeeding women because this method does not seem to affect the milk supply.  Using Depo-Provera at four to six weeks is generally safe for the mothers and infants.  Other good birth control methods for breastfeeding include all methods of natural family planning, the intrauterine device (both hormonal and non-hormonal), and the new “Implanon” (rod implanted under the skin).  Permanent sterilization (“tying your tubes”) does not directly affect the milk supply long term.  However, if the surgery involves a long period of separation for the mother and newborn baby it can indirectly interfere with getting the milk supply established if more than one feeding is missed.  Planning and communication so that the baby is not given bottles of formula when the mother is in surgery can make things go smoothly for the nursing couple.

Antibiotics:  Fortunately, antibiotics do not usually cross into the milk in high levels.  The most common complaints are some diarrhea and colic in the baby.  There may also be thrush (fungal infection in the mouth and throat) caused by the overgrowth of Candida yeast.  If there is any bloody diarrhea, the baby’s healthcare provider must be notified!

Penicillins and Cephalosporins:  This group of antibiotics produces less than 0.1% in the breast milk.  It is well tolerated, with only a skin rash sometimes seen in the infant.  As with adults, an allergic reaction is possible, but rare. Diarrhea is also rare.

Erythromycin:  Studies have shown that only a very small amount of this drug enters the milk.  Zithromax is a “close cousin” to this group.  No side effects have been noted in the infant.

Sulfonamides:  Sulfonamides are generally considered a safe group for older babies.  However, use of these drugs is discouraged during the last trimester (three months) of pregnancy and during the first month of the infant’s life.  They have been shown to increase risk of jaundice in the infant (See BABY PROBLEMS LINK).  It may be better to use a different antibiotic if possible, especially in a baby less than a month old. 

Fluoroquinolone:  These antibiotics (Cipro, Floxin, and Noroxin) are usually used for urinary tract infections.  This group should be avoided and if necessary used with some caution.  They have been shown to cause diarrhea and colitis in the infant.  If this family of drug must be used Norfloxacin is the drug of choice.

Flagyl:  Depending on the reason for treatment, this drug can be give in just one dose one time, or  two to three times a day for a longer period.  If it is given for only one dose, the mother is encouraged to pump and discard the milk for a 12-hour period.  There is still controversy whether a mother should continue to breast feed if taking this drug for up to 10 days.  Many times, a safer drug can be substituted.  If the mother is being treated for a vaginal infection, a vaginal gel may be used rather than the pills. Then almost no medication is absorbed and this is preferred to taking the pills when breastfeeding.

Aminoglycosides (including Gentamycin):  These drugs are usually only given in the hospital by I.V.  They are so poorly absorbed by the gut that they pose no problems to the breastfeeding infant.

Pain Medications: Mothers who need pain relief need to treat their pain appropriately, so that they will be comfortable and relaxed. Pain and tension can interfere with breastfeeding also, for example, in the new mother recovering from a cesarean delivery.

Opiates:  Opiates are used for severe pain.  They include morphine, Demerol, and fentanyl.  Morphine levels are low in the breastmilk, and pose a low risk for the infant.  Demerol has a longer half-life and has caused significant sedation in the infant.  It should not be used during delivery or postpartum in breastfeeding women.  Fentanyl levels are low in the breastmilk and it has a short half-life.  It poses little risk. Vicodin has been used a lot in breastfeeding mothers and has shown no problems in the infant.  Again, the mother may want to breastfeed away from the peak time of the drug in their system to be sure. Codeine should be avoided if another drug will do, as some mothers have a genetic weakness in the metabolism of this drug. This allows excessive levels to build up, possibly causing over-sedation in the baby, which can interfere with breathing.

Nonsteroidal analgesics:  This includes Naprosyn, Motrin (Ibuprofen) and Aleve- usually used for less severe pain. .  These medications are probably safe because transfer into the milk is low.  Ibuprofen is the best of this group because it can be safely used in infants and the amount in the milk is extremely low.

Acetaminophen (Tylenol):  This medication is safe to use in low to moderate doses.  This medication enters the milk poorly.  However, long-term high doses should be avoided.

Aspirin:  Levels of aspirin in breastmilk are low.  However, there may be a connection with aspirin and Reyes syndrome.  There is a possibility that an infant that breastfeeds and has a virus could contract this syndrome.  It may be safer to use one of the other medications while breastfeeding.

Anticonvulsants:  In general, anticonvulsants are safe to use for a breastfeeding mom.  They do enter the milk to some degree, and may be measurable in the infant.  The baby’s blood can be taken to measure the amount of medication in the infant’s system.  The mom also should watch for excessive sleepiness or weakness and “droopiness” in the infant.  If there is a concern about the baby, the pediatrician needs to be called immediately.

Cold remedies:  Not a lot is known about the amount of these medications in the milk.  It would be best not to use the medication while breastfeeding if possible due to the effect on milk supply (see above).  Medicated nasal sprays are probably safe because of the low levels in the blood, but are usually not recommended, as they are not very effective and can cause worsening of the congestion after 2-3 days of use.

High Blood Pressure Medication:  Some of these drugs can pass through the breast milk in doses high enough to affect the infant.  Medications in the beta-blocker family, such as Propranolol could slow breathing and cause low blood sugar in the infant.  The ACE inhibitor family should be used very carefully.  Nifedipine, in the “calcium channel blocker” family, is probably the preferred medication.  If sedation, slow heart rate, or low blood pressure is noticed in the infant, the drug needs to be changed, or breastfeeding should be stopped. The prescribing provider and the baby’s provider may need to work together to help choose the safest medication.

Dental Medications:  Most medications used by the dentist are fairly safe.  The only one that should not be used is Demerol. Local anesthetics (such as Lidocaine or Xylocaine) have minimal levels in the breastmilk.  To be safe, the mom could pump and dump for up to 6 hours after getting the medication.  More than likely, most of the medication would be out of her system by the next feeding.

Vaccines:  Most vaccines are safe to use.  All killed vaccines are safe for the breastfeeding mom.  The only live virus that is questionable is the oral polio vaccine.  This is not because it will harm the infant during breastfeeding, but because it may decrease the infant’s antibodies with later exposure.

Radiologic or Diagnostic Tests:  The type of medication used will determine what the breastfeeding mom will need to do.  In general, if a radioactive compound is used, the mom will need to discard the milk for a period of five “half-lives”.  You will need to ask your physician what the half-life of the medication is. Multiplying the number of hours in the half-life by 5 tells you how long the milk is considered radioactive and toxic. For example, if the half-life is 2 hours, breastmilk would be considered “safe” ten hours after the procedure (5 X 2 = 10).  If Iodine-131 or Iodine -125 is used, breastfeeding needs to be stopped completely as these tend to linger in the milk for extremely long periods, and can be unpredictable.  Most medications used for CAT scans and MRI’s are rapidly cleared from the body and do not get absorbed orally by the infant.  In those cases, pumping and dumping for one feeding should be safe. Your doctor may be able to consult with the radiologist and give you more information.

Drugs of Abuse:  All brain-altering drugs should be avoided by breastfeeding mothers.  They readily enter the breastmilk and will affect the infant.  Cocaine, pot, and PCP will enter the infants system and can cause positive urine tests for up to a full month.  Cocaine in particular is highly dangerous and should never be used when breastfeeding. Anything that the mother smokes will be inhaled by the infant and have direct effects on the infant.

Antidepressants:  All antidepressants are secreted into the breastmilk to some degree.  This has been an area of a lot of research lately.  The tricyclic antidepressants (TCAs) do not seem to have any long term effects in breastfeeding infants, however, these are not always safe and effective for the mother.  SSRI antidepressants such as Prozac, Zoloft, and Paxil have fewer side effects in the adult, and can be used with caution in the breastfeeding mom.  Prozac is usually not preferred. It has shown side effects in the baby like colic and nervousness, or the opposite- extreme sedation.  Studies have shown that Zoloft has little or no absorption in the breastmilk and cannot be found in the infant’s blood.  Paxil has also been shown to have extremely low levels in the breast milk. Celexa and Lexapro, being newer, have less data that can be used to make a good recommendation.  In general, short acting formulas of antidepressants are preferred over the once a day, long acting forms, so that the nursing can be done around the dosing as described above. This strategy will minimize the baby’s exposure to the medicine. Herbal products (such as St. John’s Wort) should be used with extreme caution because no studies have been done and there is no information on their safety with breastfeeding.

In Conclusion

It is important for you to know the medications you are taking. Likewise, your healthcare provider needs to know about your breastfeeding, the age of your baby, etc. to help you make an informed choice about any therapy that is needed.   A word of caution: Almost all “manufacturer’s information” provided for consumers (including the PDR or Physician’s Desk Reference) will caution AGAINST breastfeeding without consideration of the mother’s need for treatment and the need and desire to continue breastfeeding. This unqualified recommendation is partly due to their need to protect themselves from legal liability.
However, your healthcare provider can provide a more balanced point of view. You should discuss any medications, either prescribed or over-the-counter, with your healthcare provider to make sure they are the safest options for you and your infant.  Many times, with communication and care breastfeeding can continue while mother is being treated for minor illnesses or chronic problems.

For more information, Dr. Thomas Hale has a website about medications and their safety in breastfeeding. Your physician or health care provider might appreciate being given this reference, as they may not have all the information they need to help make good choices in managing both your medical care and breastfeeding.

The website is
His textbook Medications and Mother’s Milk is considered an easy to use and authoritative text on the subject and was used as a reference for this article.

Hale, T. (2006) Medications and Mother’s Milk, 12th ed.  Pharmasoft Publishing