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Drugs and Breastfeeding
by Anne Smith, IBCLC

As the number of nursing mothers continues to increase, so does the use of drugs, both legal and recreational. As a nursing mother, you should be aware that there are three things we know for sure about drugs and breastmilk:

  • Nearly all drugs pass into human milk.
  • Almost all medication appears in very small amounts, usually less than 1% of the maternal dose.
  • Very few drugs are contraindicated for nursing mothers.

The issue of which drugs are safe to take during lactation is quite complicated. Many factors must be taken into consideration, such as:

  • The route of administration (your baby is always exposed through the GI tract, but drugs can enter your system several different ways: orally, intravenously, intramuscularly, topically, or through inhalation--topical medications (skin creams) and medications inhaled or applied to the eyes or nose reach the milk in lesser amounts and more slowly than other routes and are almost always safe for nursing mothers; oral medications take longer to get into the milk than IV and IM routes (the drug must first go through the mother's GI tract before it enters the bloodstream, and the milk supply)--with IV drugs, the medications bypasses the barriers in the GI tract to enter the milk quickly and at higher levels, and with IM injections, drugs transfer quickly into the milk because the muscles have so many blood vessels, so the drug enters the bloodstream quickly.

  • The amount taken (the higher the dosage, the more the drug transfers into milk).

  • How often you take the drug (medications taken 30 to 60 minutes before you feed are likely to be a peak blood levels when your baby nurses).

  • Your baby's age and maturity level (premature infants have immature kidney and liver functions and may have trouble processing and eliminating even small quantities of drugs that might not cause problems for larger, full-term infants; however, even full-term baby's protective metabolic systems are not fully developed for the first week of life, so they may not be able to handle chemicals in the milk as well as a baby who is several months old).

  • The frequency and volume of feedings (the baby who is nursing once or twice a day, and is supplemented the rest of the time, will receive less of a drug than the baby who is totally breastfed and may nurse 10-12 times a day). Duration of drug therapy (a medication taken for weeks or months may have a greater impact on nursing than one taken for just a few days).

  • The type of medication (characteristics such as the molecular weight, how fat soluble the drug is, and how long it takes for it to be eliminated from your system, or it's half-life, all affect how much of the drug is transferred into your milk).

  • In the last decade or two, as breastfeeding rates have increased, so have the accuracy of the methods we use to measure drugs in human milk. This is good because in certain situations, such as nursing a very sick premature baby, knowing what medications appear in even very tiny amounts can be significant. On the other hand, some doctors are hesitant to prescribe any medication for a nursing mother once they know that even a tiny amount enters the mother's milk. Many doctors are afraid to prescribe a drug because of the conservative approach taken toward giving drugs to a pregnant woman. They feel that if a drug might possibly cause birth defects in a pregnant woman, then they shouldn't give it to a lactating woman. The difference is that while the placenta lets drugs enter to cross into the developing fetus's bloodstream, the breast serves as a very effective barrier for a fully developed infant.

  • We also live in a society, which, in general, doesn't place a high value on breastfeeding, but does believe in suing anyone and everybody, especially doctors. Doctors tend to err on the side of caution and recommend that a mother wean rather that do research and reassure the mother that the medication is safe for her baby (as the majority of drugs are), or explore alternative, safer medications. Both of these options involve the doctor's willingness to spend time on research, and obtaining access to good lactation information. Many doctors do not have the training or the resources to access this kind of information. Most do not have specific reference books dealing with drugs and breastfeeding in their office, especially if they are not pediatricians or obstetricians. Most of the time, their primary source of drug information is the famous PDR - (Physician's Desk Reference-also known as the doctor's bible.). You should be aware that the PDR contains very little information about breastfeeding, and bases its recommendations on the idea that no drug should be taken by a nursing mother unless it has been proven absolutely safe in all circumstances. The problem with that is that there is virtually no drug in the world, including Tylenol, that can be said to be absolutely safe all the time. The PDR is not the best source of breastfeeding information, because it is an unfortunate fact that pharmaceutical manufacturers often discourage breastfeeding solely for fear of litigation, rather than for well-founded pharmacologic reasons.

  • In deciding which drug to take, you should always look at the situation from a risk/benefit perspective: The benefits of breastfeeding are well known and undisputed, so doctors should recommend a mother wean only when there is scientific documentation that a drug will be harmful to her infant. In the rare cases where that is proven, a doctor who believes in the value of breastfeeding should take the time to explore alternative therapies, or if nursing must be interrupted, encourage the mother to continue pumping her milk to maintain her supply and return to breastfeeding as soon as possible. If your doctor prescribes a drug which he says in incompatible with breastfeeding, it is reasonable to ask for documentation and/or alternative medications. If your doctor isn't flexible about this, and doesn't understand how important continuing to breastfeed is to you, it makes sense to seek another opinion.

Here are some general guidelines for taking drugs while nursing:

  • Only take a medication if you REALLY need it. Consider alternative, non-drug therapies if possible.

  • If you have a choice, delay starting the drug until the baby is older. A drug which might cause problems for a newborn may be fine for an older, larger, more mature infant

  • Take the lowest possible dose for the shortest possible time.

  • Avoid drugs with long-half lives, sustained-release preparations, or high M/P (milk to blood) ratio. If the M/P ratio is one or higher, that means that more of it is transferred into the milk

  • Schedule the doses so that the lowest amount gets into the milk (take it soon after a feeding, preferably a night feeding, rather than right before nursing).

  • Watch for reactions such as sleepiness, rashes, diarrhea, colic, etc. Although reactions are rare, it is important to keep your doctor informed of any changes.

  • If you must take a drug that is contraindicated, and no alternatives are available, get a good electric pump to maintain your milk supply if you need to wean for more than a day or two. Your supply will build up when the baby starts nursing again.

Some very general information about drugs that are usually considered safe to take during breastfeeding follows:

  • If the drug is commonly prescribed for infants, it is most often safe to take while nursing, because the baby generally gets a much lower dose from the milk than he would from taking it directly. Examples are most antibiotics, such as amoxycillin.

  • Drugs considered safe during pregnancy are usually, but with a few exceptions, safe to take while nursing.

  • Drugs that are not absorbed from the GI tract (stomach or intestines) are usually safe. Many of these drugs are injected, such as heparin, insulin, lidocaine, or other local anesthetics. Immunizations such as german measles, flu shots, TB tests, or Hepatitis A and B, are not harmful to the baby--even the ones with live viruses.

Most antiepileptic medications, antihypertensive medications, and nonsteroidal antinflammatory medications are safe during lactation. Antidepressant medications and their use by nursing mothers are being extensively studied, as more and more women are currently being treated for depression, which often occurs during the postpartum period. Some studies suggest that the one-year old infants of mothers who are depressed may not exhibit normal neurobehaviorial development. It is therefore important to treat depression and also to continue breastfeeding during treatment, because one of the many benefits of breastfeeding is its positive effect on neurodevelopment.

Use of antidepressant medication does not normally contraindicate breastfeeding. We do have more information about the safety of some medications than we do about others.

Currently, the most widely prescribed antidepressants are SSRI (seretonin-selective reuptake inhibitors) such as Paxil and Zoloft. Both appear in mother's milk in very small amounts. Zoloft is the preferred antidepressant for nursing mothers because it is effective for many mothers, and studies on breastfed babies show that their blood levels are usually too low to be measured. It is usually the first medication to try.

Paxil is usually considered safe for nursing mothers. It seems to get into the milk in very minimal amounts. Prozac is not the drug of choice because it has a longer half-life and more appears in milk that the other SSRI medications. Prozac should be avoided if the mother is nursing a premature or newborn infant, especially if she took the medication during her pregnancy. Treatment with Prozac is less likely to cause problems if the baby is 4-6 months old because the baby is better able to eliminate it when he is older.

The tricyclic antidepressants (such as Trofanil and Pamelor) appear in milk in very small amounts, but they take several weeks to start working and many mothers have troubling side effects. According to Dr. Hale (Medications and Mother's Milk, 2000) ".many studies show minimal to no effect of the tricyclics on infants..". Wellbutrin (Zyban) is an older antidepressant that has a different structure from SSRI and tricyclic medications. It may appear in milk, but the amount is so low that it is unlikely to cause problems in the breastfed baby. It is often used to help with smoking cessation.

The herbal preparation St. John's Wort is currently being studied extensively, but there is not as much information about its effect on breastfeeding as there is about the prescription antibiotics. Because there is more information available about these other medications, it is suggested that they be used during lactation rather than St. John's Wort. Use of this herb is not recommended during pregnancy.

For information about OTC (over the counter) medications, see article on When a Nursing Mother Gets Sick.

There are some prescription drugs which should never be taken during breastfeeding. These include Bromocriptine (also called Parlodel - this used to be given to formula feeding mothers soon after birth to dry up their milk, but was discontinued due to side-effects); Ergotamine (used to treat migraines), and Cyclosporine, Cyclophosphamide, Methotrexate, and Doxorubicin, used to treat cancer or organ transplant rejection.

There are also a number of radioactive compounds that require temporary cessation of breastfeeding. A nuclear medicine physician can work with you before the test is done to use a compound that has the shortest excretion time in breastmilk. Try to pump enough milk to freeze before the test to feed the baby during the time the milk is unsafe. Pump to maintain your milk production but discard your milk until it is screened by the radiology department to make sure it is safe to resume nursing.

There are some "recreational drugs" that should not be used at all, or used only in moderation while you are nursing. These include alcohol, caffeine, nicotine, marijuana, cocaine, heroin, hallucinogens, and amphetamines. With cocaine, heroin, PCP (angel dust), and LSD, the data is clear: they should never, EVER be used by nursing mothers, even in small doses. They can and do cause serious medical problems in you and your baby. If you must abuse these drugs, don't nurse your baby--and get some help.

Although ideally, all nursing mothers would be drug-free all the time, the reality is that many mothers will smoke cigarettes, drink alcohol or coffee, toke on a joint, or take uppers occasionally. These drugs are so prevalent that it is worth addressing their use. We get back to that risk/benefit thing we discussed earlier. We know the benefits of breastfeeding versus the risks of artificial feeding (see article Why Breastfeed?). Although none of the drugs mentioned above are good for you or your baby, there is no evidence of serious harm, especially when used in moderation.

When it comes to smoking, avoid having the baby breathe second-hand smoke of any kind. Nicotine in large doses can cause low milk supply, poor let-down reflex, and intestinal upsets in the baby. If you can't quit, smoke after you nurse, don't smoke around the baby, and cut down as much as you can. If you smoke fewer than a half a pack a day, the risks to the baby are small. The fewer cigarettes you smoke, the smaller the chance that you will encounter problems.

Marijuana is the most commonly used illegal drug among nursing mothers. The active ingredient, THC, is concentrated in human milk and may make your baby sleepy. Inhaling passive smoke increases the amount he absorbs. As with nicotine, exposing your baby to second-hand smoke increases the amount of the drug he receives. There is one study that found an exposure to marijuana through mother's milk was associated with decreased motor development at one year. (Ashley & Little, 1990) Because there is little evidence of real harm, it is probably better to continue nursing if you smoke pot occasionally than to wean and deprive the baby of the protective benefits of breastfeeding.

Alcohol gets into your milk quickly, but is also diluted relatively quickly by the water in the baby's body. Alcohol ingestion can decrease your milk supply, and may delay your baby's motor development, especially if you drink large amounts on a regular basis. There no evidence that alcohol consumption in moderation poses a serious risk for your baby. A glass of wine with dinner, or an occasional couple of beers shouldn't make you feel guilty. If you want to be conservative, wait at least two hours for every drink you consume before you nurse your baby. This means that if you want to go out and celebrate your anniversary and really blow it out, you nurse the baby before you leave, feed him expressed milk or formula during the night, have several drinks (I found that the combination of sleep deprivation and not drinking for nine months of pregnancy made me a very cheap date--one or two drinks and I was ready to nod off.) and then start nursing again in the morning.

Some recommendations on limiting alcohol intake:

  1. Use expressed milk to feed if needed after drinking

  2. Eat before and while drinking to minimize the alcohol absorption

  3. Drink Slowly. Sip your drinks and space them 2-3 hours apart.

  4. Choose drinks low in alcohol, or diluted with water or juice (such as champagne punch, 3oz port or vermouth, 5oz. of beer or wine).

  5. Factor in your baby's age. Infants under four weeks of age detoxify alcohol alcohol at a lower rate than babies over three months, due to liver maturation, and preemies' livers are less mature than full-term babies. As with any drug, you need to be more conservative if you are nursing or pumping milk for a tiny preemie or new born than if you are breastfeeding an older, more mature baby (6-12 months).

The caffeine in five or less cups of coffee each day will not cause a problem for most nursing mothers and babies. If you consume more than that, some babies will be fussy and over-stimulated. Some babies and mothers are more sensitive to caffeine than others. If you think it's causing a problem, try substituting decaf products for a couple of weeks and see if it makes a difference.

When you use amphetamines in the usual prescription doses, they are compatible with nursing. If you abuse them, they can accumulate in your milk, but even then normally don't cause problems for the baby. Symptoms in the baby with amphetamine abuse may include irritability and sleeplessness--so don't take more than the doctor recommends. Duh.

Most drugs, including chocolate (yes, it's kind of a drug) and herbal preparations are safe when taken in moderation. Keep this in mind while you are nursing. No, you don't have to be Mother Teresa and give up all your vices. Yes, you do have to exercise common sense and self control and make some sacrifices for this new little person in your life--but not as many as you had to make while you were pregnant.

For more detailed information about the safety of specific drugs during lactation, here are some resources:

The AAP (American Academy of Pediatrics) has published a statement called "The Transfer of Drugs and Other Chemicals Into Human Milk". It has 8 Tables--Drugs That Are Contraindicated During Breastfeeding, Drugs of Abuse Contraindicated During Breastfeeding, Radioactive Compounds That Require Temporary Cessation of Breastfeeding, Drugs Whose Effect on Nursing Infants Is Unknown But May Be of Concern, Drugs That Have Been Associated With Significant Effects on Some Nursing Infants and Should Be Given to Nursing Mothers With Caution (be aware that this category includes drugs that are known to have caused one single case of diarrhea--that's how conservative they are), Maternal Medications Usually Compatible With Breastfeeding (a long list), Food and Environmental Agents: Effect on Breastfeeding, Generic Drugs and Corresponding Trade Names, and Trade Names and Generic Equivalents. The AAP statement was first published in 1983, and revised in 1989. Because so many new drugs have come out during the past ten years, many drugs currently in use have not been reviewed by the AAP and don't appear on this list.

Two other excellent resource books, and the ones that I use all the time, are written by Dr. Thomas Hale, an expert on drugs and breastfeeding. He publishes an excellent reference book called Medications and Milk, and updates it every year. It provides detailed information on drugs, including herbs, and includes useful information about the drug's half-life, milk/plasma ratio, side effects, AAP ratings, and more. He also has a book called Clinical Therapy in Breastfeeding Patients (first edition) that gives an overview of medications that are useful for specific conditions. This is useful for doctors who are prescribing for lactating patients, especially because it gives alternative medications for different conditions. Both books are available in paperback, and I think no doctor's office should be without them. Dr. Hale's website: http://neonatal.ttuhsc.edu/lact/.

Another resource is the Lactation Study Center in Rochester, New York. Designed primarily for physicians, they will search their data bank for information and get back to you quickly. This includes drug information as well as information about any breastfeeding topic. Ruth Lawrence, Professor of Pediatrics and OB/GYN (and mother of 9 ) is probably the best known medical expert in the field of lactation, and is the author of another excellent resource book: Breastfeeding: A Guide for the Medical Profession (5th edition). The number for the Lactation Study Center is 716-275-0088.

Remember that not all herbal preparations are safe to take while breastfeeding. While herbs are "natural", they can be quite potent and cause serious side effects. For more information about herbs and breastfeeding, check out http://lalecheleague.org/llleaderweb/LV/LVJunJul98p43.html.

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