Breastfeeding and Medications

Here is one of the most common breastfeeding questions we 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, the mother”.


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.  This response is a complete cop-out. Telling the mother that there are no studies on a particular drug and breastfeeding 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. There are ways, however, of deciding if a drug taken by the mother is compatible with continued breastfeeding. Good studies, on more than a handful of mothers and babies, are nice to have, but not always necessary.


In fact, 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 to a mother: “Yes, keep breastfeeding, it is best for the baby and for you”. 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.



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 and for the mother.


Whereas minuscule amounts of drug getting into the milk only rarely has any risks 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 cancerovarian cancer and uterine cancer. As well, she has a lower risk of high blood pressure, high cholesterolcardiac diseaseosteoporosis,  insulin resistance and a greater chance of losing the weight gain during pregnancyAnd 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 the toddler from the breast can result in serious and prolonged 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?  The minimal amount 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.


  1. Botox is a perfect example and one of the most common questions we get. Botox stays where it is injected, otherwise it would be of no use. It doesn’t get into the blood, so cannot get into the milk.
  2. Drugs that are used to treat varicose veins are another group of drugs we hear about all the time. Typically, mothers are told they must not breastfeed after these highly irritating chemicals are injected into the veins. But if they got into the general circulation, the problem would be for the mother. But they don’t get into the general circulation, so they cannot get into the milk.


So what information is available?


1. In some cases, a 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, Crohn’s disease 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.  Another drug commonly used for multiple sclerosis is glatiramer (Copaxone) also does not get into the milk because the molecule is too big.  In addition, glatiramer is not absorbed from the intestinal tract.


• 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 (Coumadin), 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).


Warfarin has been used for decades to prevent blood clotting and if the patient’s prothrombin time (a measure of how easily the patient bleeds) is followed and kept within a certain range, it is safe for the patient.  And safe for the baby.  But here is a perfect example of how doctors do not consider breastfeeding important or consider it at all.  There are several new medications to prevent clotting.  And doctors love new medications.  They too often believe the “hype” from the drug company representatives and advertisements and then a few years later it is found not to be as safe for the adult as the doctors were told.  But instead of prescribing warfarin for the mother and following the prothrombin time, they prescribe the new medication and tell the mother she has to stop breastfeeding because “there are no studies” available.


3. Many drugs given to mothers may get into their milk, but the baby will not absorb the drug and thus such a drug 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.  If you are taking such a drug, check the label on the container.  It will usually say something like “Do not break, chew, or crush”. Why? If the protective covering of the drug is disrupted, the drug will be destroyed in the mother’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!  Because at the same time we are interrupting breastfeeding and a week or 10 days without breastfeeding is almost surely going to be the end of breastfeeding.  Mothers have also been told that the baby may become allergic to the antibiotic. That is highly unlikely. Besides, doctors are rarely held back from prescribing antibiotics for babies, far too often for illnesses that don’t require antibiotics.  And if the baby goes on formula, the baby may become allergic to components of the formula.


• 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 and weakness 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!


What about doxycycline used not infrequently now for Lyme disease, malaria prophylaxis, treatment of acne and rosacea and several other reasons. Is it contraindicated during breastfeeding?  It is not contraindicated during breastfeeding, though some experts recommend limiting treatment to 3 to 6 weeks which may be a problem for mothers taking it for acne or rosacea, since that requires long term treatment.


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%.  Nifedipine, in the same family of drugs as Nitrendipine, is 92 to 98% protein bound, and oral absorption from the intestinal tract is 50%. Both safe.


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.  But monoclonal antibodies don’t get into the milk in the first place.


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 who contacted me was told she would have to interrupt breastfeeding for 8 days after the surgery.  This is completely unnecessary.  After all, we frequently give babies having surgery the very same medication.


Two types of drugs are usually given during general anesthesia, some given by intravenous injection, usually to relax the patient, and/or to decrease lung 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 and should 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 even 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, and the “social lubricant” that alcohol causes 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 as if it were water, 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” because it makes no sense. 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 de-alcoholized beer actually contains 0.6% alcohol, almost 8 times more than 0.08%, 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.  So, mothers should not drink so much that their judgement is impaired.


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 potentially dangerous for the baby.  For example, if the mother is high on marijuana and the baby is sick and gets sicker, would she notice that the baby is sick? Would she get into her car and drive the baby to the doctor or the hospital?


The tetrahydrocannabinol (THC), the compound in marijuana is very highly protein bound, 99.9% protein bound.  Furthermore, if taken by mouth (as might the baby) it is very poorly absorbed from the intestinal tract with only 6 to 20% of it absorbed.  With such high protein binding, it is unlikely that significant amounts will get into the milk.  But note again, that the “high” the mother experiences could last for a few hours, and so her judgement will also be impaired.


Cannabidiol (CBD), is now used widely as treatment for various medical disorders (medical marijuana) and thus not really a drug of recreation.  It has low oral absorption, less than 20% of the orally taken dose, is absorbed.


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 manufacturer of 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 many doctors don’t know the first thing about maternal medications and breastfeeding and will agree with whatever the pharmaceutical company says? Which is, “check with the doctor”!?


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 a brand new 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 still 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=breastmilkbottle feeding=breastfeeding, it’s all the same. But it’s not all the same.


5. So, although there are definitely exceptions, most doctors are not to be believed about information they give about drugs and breastfeeding. A mother should take “You must take thisdrug 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: International Breastfeeding Centre (IBC), 2017, 2018, 2020


This information sheet may be copied and distributed without further permission on the condition that you credit International Breastfeeding Centre, it is not used in any context that violates the WHO International Code on the Marketing of Breastmilk Substitutes (1981) and subsequent World Health Assembly resolutions. If you don’t know what this means, please email us to ask!


Questions or concerns?  Email Dr. Jack Newman (read the page carefully, and answer the listed questions).

Make an appointment at the Newman Breastfeeding Clinic.