Maternal Medications and Breastfeeding

Here is one of the most common questions I receive: “I have been put on drug x and have been told I cannot breastfeed. Is that true?”


The short answer is: Almost no medication taken by the mother requires her to stop or interrupt breastfeeding. The real question, though, is “Which is safer for the baby? Breastfeeding with minuscule amounts of drug in the milk, and the amounts in the milk are almost always minuscule, or artificial feeding?” The answer is, with very few exceptions, “keep breastfeeding, it’s better for your baby and also for you”.


This is true, in spite of doctors telling mothers they cannot breastfeed because there are no studies that have been done on most drugs and breastfeeding. But the fact is, even when there have been studies, they have often been done with only 2 or 3 breastfeeding mothers and their babies. And even if such a study on 3 mothers and their babies shows that almost no drug gets into the milk, what does that tell us? Not much. Telling the mother that there are no studies on a particular drug usually is not true. Often there are studies, on small numbers of mothers and babies, but saying this is a handy, plausible way for the physician or pharmacist to tell the mother that she cannot breastfeed.


However, there is good, scientific information, very useful information, with regard to the majority of drugs. And the information available makes it possible, in the vast majority of cases, to be able to say that a particular drug is compatible with continued breastfeeding. A good text is Medications and Mother’s Milk, by Thomas Hale. But you don’t really have to buy the book. You can get all the information you need about most drugs on Wikipedia.  And by sending me your question.


Help with breastfeeding


Why is continuing breastfeeding almost always safer for the baby?


The reason is that little word “minuscule”. With the vast majority of drugs, so little of the medication enters the mother’s milk, that when one compares the risks of not breastfeeding to the risk, almost non-existent, of that tiny amount of drug in the milk, it is clear that continuing breastfeeding is safer for the baby.


The risks of not breastfeeding are well documented, not only for the baby, but also for the mother, so the risks for the mother also need also to be taken into account. Which risks?  Of course, there is the risk of painful engorgement and mastitis despite pumping. But I am talking long term: a mother who breastfeeds has a lower risk of breast cancer, ovarian cancer and uterine cancer. As well, she has a lower risk of high blood pressure, high cholesterol, and insulin resistance. And the longer she breastfeeds, the lower her risks.


When it is a toddler at the breast, another issue arises. Many toddlers are very attached to breastfeeding, and whether one agrees with toddlers breastfeeding or not (what is wrong with it?), forcing them from the breast can result in serious emotional distress. Any mother faced with a “need” to stop breastfeeding an 18 month old, and trying to do so, knows that this is true.


Why are the amounts of most drugs in the milk so low?


The amount of any drug that gets into the milk depends first and foremost on its being in the blood. If the drug is not in the blood, it cannot get into the milk. This is important when mothers are told that they cannot breastfeed if they are using eye drops, for example. How much drug could get into the blood since the cornea of the eye has no blood supply?  Some that goes down the tear ducts into the mother’s mouth?  That is ridiculous.  It is the same for tooth whitener as the enamel of the teeth has no blood supply. I receive a surprising number of emails asking about tooth whiteners.


A drug that is not absorbed into the mother’s blood from her intestines or elsewhere also cannot get into the milk.
So what information is available?


1. In some cases drug does not get into the milk at all, the amounts are zero. Here are some examples:


• Monoclonal antibodies such as etanercept (Enbrel) and infliximab (Remicade) and many newer ones are now commonly used to treat inflammatory diseases and other diseases such as multiple sclerosis, psoriasis, rheumatoid arthritis and many others thought to be due to an abnormal immune response. These monoclonal antibodies, also called biologicals, are, essentially, antibodies and as such are very large molecules with a molecular weight of approximately 150,000. Any drug having a molecular weight of 800 or more is too large to get into the milk.


• Heparin is a drug used to prevent clotting of the blood, an anticoagulant. It is too large to get into the milk. Even “low molecular weight” heparin with a molecular weight of 4500, is only “low molecular weight” compared to regular heparin with a molecular weight of 15,000.


• Interferons, used for many illnesses, including multiple sclerosis have a molecular weight of between 20,000 and 30,000. Too large to get into the milk.


• Luteinizing hormone and follicle stimulating hormone frequently used to induce ovulation, have molecular weights in the thousands, so too large to get into the milk.


2. An important factor determining how much of a drug gets into the milk is how much of the drug is bound to protein. Only drug that is not attached to protein can get into the milk; only the “free” drug can get into the milk. Below is a random list of commonly used drugs that are very highly protein bound:


• Ketorolac (Toradol): 99% of the drug in the mother’s blood is bound to protein, so only 1% of the already tiny amount of drug in the mother’s blood can actually get into the milk. Ibuprofen (Advil) is more than 99% bound to protein. Meloxicam (Mobic) is >99% protein bound. Diclofenac (Voltaren) is 99.7% protein bound. In fact, as with the above, most of the nonsteroidal anti-inflammatory drugs (NSAIDs), have similar protein binding.


• Others: warfarin, an anticoagulant (99% protein bound), diazepam, an anti-anxiety medication (99% protein bound), propranolol a beta-blocker used to treat high blood pressure, migraines, the symptoms of overactive thyroid (90% protein bound).


3. Many drugs given to mothers may get into their milk, but the baby will not absorb the drug and thus it should be safe during breastfeeding.


• A special situation is that of the proton pump inhibitors, used by millions of people to treat gastro-esophageal reflux disease (GERD); for example, pantoprazole (Tecta) and lansoprazole (Prevacid). These drugs are immediately destroyed by stomach acid but, because they have a protective covering, they are protected from destruction in the mother’s stomach and are well absorbed by the mother. However, whatever drug gets into the milk (and that is a minuscule amount), no longer has the protective covering and is destroyed in the baby’s stomach.


• Several antibiotics may get into the milk but are not absorbed by the baby. Gentamicin and tobramycin are in the family of antibiotics called aminoglycosides. Vancomycin is another drug that may get into the milk in tiny amounts, but is not absorbed from the baby’s intestinal tract. Their absorption from the gut is essentially zero. Thus, whatever tiny amount of the drug gets into the milk will end up in the baby’s diaper. Some will argue that the antibiotic may cause a change in the baby’s microbiome (intestinal flora), but then if the mother is told she cannot breastfeed and gives the baby formula, then the baby’s microbiome will change as well.  Is it better to change the microbiome with formula?  No!


• Another interesting example is tetracycline, a broad spectrum antibiotic taken mostly these days for the treatment of acne. Everyone seems to believe that tetracycline is contraindicated during breastfeeding because it is contraindicated during pregnancy and in children under the age of 8 years (some say 12 years) due to discolouration it can cause in developing teeth and bones.  But the pharmacist will tell you not to take tetracycline with milk.  Why?  Because tetracycline combines with calcium in the milk and is not absorbed.  If the breastfeeding mother is taking tetracycline, how will the baby get the tetracycline?  With milk!


4. Many drugs result in very low blood levels in the mother’s blood because the majority of the drug is somewhere else in her body than in her blood. For example, most of the antidepressants like sertraline (Zoloft), citalopram (Celexa), and most others in the same family of drugs, naturally reside in the brain where they affect the mother’s mood, and are not in the blood except in minuscule amounts.


5. Many drugs have poor absorption from the baby’s intestinal tract, so that even if some drug gets into the milk, very little will be absorbed into the baby’s blood.


Propranolol, mentioned above as having 90% protein binding, is an example of how we can put two or more pieces of information together, even if “not enough studies have been done”. We also know that only about 30% of the propranolol in the intestines is actually absorbed into the blood, not only for the mother but also for the baby. Furthermore, we know that there is very little propranolol circulating in the mother’s blood. So, is propranolol safe to take during breastfeeding? Safe!


Nitrendipine (Baypress), a drug used for hypertension? 98% protein bound, and oral absorption of less than 20%.


Other drugs? The monoclonal antibodies (mentioned in point 1.) also do not get absorbed from the intestinal tract at all as they are almost surely completely destroyed in the baby’s stomach.


Breastfeeding after general anesthetic


Mothers are usually told that they will have to interrupt breastfeeding for 24 to 48 hours after surgery under general anesthetic.  Recently one mother was told for 8 days after the surgery.  This is completely unnecessary.


Two types of drugs are usually given during general anesthesia, some given by intravenous injection, usually to relax the patient, or to decrease secretions and, to put the patient to sleep, gas is given by mask or through a tube in the trachea.  With regard to the drugs given by intravenous injection the issue is no different than any other drugs given by mouth or by injection.  The concentration of the drugs in the mother’s blood given by injection, especially intravenous injection, will rise quickly and then start to decrease immediately after the injection.  With regard to breastfeeding, the concentration in the milk will remain low and will be very low by the time the mother wakes up.


As for the gas the mother inhales, well, the effects of the gas occur by inhaling it.  Even if some entered the milk, the gas has no effect in the baby’s stomach.  It must be inhaled.


The bottom line?  The mother can breastfeed as soon as she is awake and alert enough not to drop the baby.  If the mother is alert, the drugs have essentially left her body and no longer get into the milk, if they ever did.


Some other drugs


1.Alcohol. Alcohol is not different from most other drugs in that very little gets into the milk.  It is very different in that there is a level of paranoia amongst certain persons who state that 1 drop of alcohol ingested by the baby is poison and dangerous.  This is absurd.  The reasons for which people drink alcohol are complex, but in general, people, including breastfeeding mothers, drink alcoholic beverages for the effect that alcohol has on them.  People, including breastfeeding mothers, enjoy the relaxation effect that small, reasonable amounts of alcohol have on them, and the “social lubricant” that alcohol has in a gathering of people.


Alcohol is also special from the point of view of breastfeeding in that it moves back and forth between blood and milk and then back again from the milk to the blood which means that as the alcohol blood level decreases (as it does if the mother does not drink more), the alcohol in the milk will move back into the blood to “even out” the levels. This means that the mother should not pump her milk “to get rid of the alcohol”. The levels of alcohol in the milk are so low that it is not helpful to pump out the milk.  Why is it not helpful?


In most jurisdictions in North America, Australia and Europe, the amount of alcohol in the blood for a person to be considered too impaired to drive is 0.05% or in some 0.08%.  Now, if the mother’s blood contains 0.08% alcohol, so will her milk contain 0.08% alcohol.  If one considers that alcohol-free beer actually contains 0.6% alcohol, almost 8 times more than 0.08%, then it is obvious that the concentration of alcohol in the mother’s milk is negligible.  And not going to harm the baby.


The problem is that in most families, it is true that it is the mother who cares for the baby and in breastfeeding families this is true as well.  A mother has to be able to take care of her baby without her judgment regarding the baby’s needs being impaired.  That’s all.


See this article: Basic Clinical Pharmacology and Toxicology 2014;114:168-173. One conclusion: “It appears biologically implausible that occasional exposure to such amounts should be related to clinically meaningful effects to the nursing children. The effect of occasional alcohol consumption on milk production is small, temporary and unlikely to be of clinical relevance. Generally, there is little clinical evidence to suggest that breastfed children are adversely affected in spite of the fact that almost half of all lactating women in Western countries ingest alcohol occasionally.”  


Finally, there is no evidence that the baby getting insignificant amounts of alcohol in the milk will predispose the baby to abusing alcohol in later life.


2. Other recreational drugs.  These drugs, for example, marijuana and cocaine, have the same negative associations as does alcohol and on top of that in most jurisdictions are illegal to possess.  I am not recommending that anyone break the law.  But what I said about alcohol is true of these drugs as well.  That is, if the mother is so impaired that she cannot make a good judgment about what her baby needs, that is dangerous for the baby.  For example if the mother is high on marijuana and the baby is sick and gets sicker, would she get into her car and drive the baby to the doctor or the hospital?


What if my doctor or pharmacist says I need to stop breastfeeding with a particular medication?


1. Unfortunately, most doctors, including pediatricians and obstetricians, and even pharmacists (yes, even pharmacists), if they even bothered checking what the company that makes the drug says in its prescribing information, would not get good information. Basically, all drug companies say that breastfeeding should not continue while taking the drug. Or, at best, the information that comes with the drug will say that the breastfeeding mother should check with their doctor. But the companies write this to cover their medical-legal liability. They don’t give a damn about the mother and the baby. And what’s the point of asking the doctor, since most doctors don’t know the first thing about maternal medications and breastfeeding and will agree with whatever the pharmaceutical company says?


2. But the truth is that many doctors don’t bother to check even the poor information about the drug from the manufacturers and merely assume that any drug is contraindicated during breastfeeding. They may not think “Oh, I prescribed this same drug for the baby 2 weeks ago and I wasn’t particularly worried about it.”


3. In the rare case where a drug is truly of concern, usually there are alternatives that could be used instead. For example, a mother taking heparin during the pregnancy might opt to continue heparin after the baby is born in order to avoid an oral anticoagulant. She might do this so she can breastfeed her baby, in spite of the pain of injecting heparin. Unfortunately, too many doctors base their decisions on which drugs to use on pharmaceutical company marketing (conferences where paid representatives of the companies tell them how wonderful such and such a drug is) and the pharmaceutical company representative that drops by the doctor’s office for 30 minutes every few months to keep him up to date.  Incidentally, warfarin, an oral anticoagulant which is still the most commonly used oral coagulant, is okay to take while breastfeeding.


4. And why do so many physicians assume that any and every drug is contraindicated during breastfeeding? Basically, because they don’t believe that it matters if the mother breastfeeds or not. Formula=breastmilk, bottle feeding=breastfeeding, it’s all the same. In fact, it’s not.


5. So, although there are definitely exceptions, doctors are not to be believed about information they give about drugs and breastfeeding. A mother should take “You must take this drug and you cannot breastfeed while taking it” with a grain of salt and seek a reliable source for information.


For breastfeeding help in the Toronto area, make an appointment with our clinic.


Copyright: Jack Newman, MD, FRCPC, 2017

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