Over the years, far too many women have been wrongly told they had to
stop breastfeeding. The decision about continuing breastfeeding when the mother
takes a drug, for example, is far more involved than whether the baby will get
any in the milk. It also involves taking into consideration the risks of not
breastfeeding, for the mother, the baby and the family, as well as society. And
there are plenty of risks in not breastfeeding, so the question essentially
boils down to: Does the addition of a small amount of medication to the
mother’s milk make breastfeeding more hazardous than formula feeding? The
answer is almost never. Breastfeeding with a little drug in the milk is almost
always safer. In other words, being careful means continuing breastfeeding, not
stopping.
Remember that stopping breastfeeding for a week may result in permanent
weaning since the baby may then not take the breast again. On the other hand,
it should be taken into consideration that some babies may refuse to take the
bottle completely, so that the advice to stop is not only wrong, but often
impractical as well. On top of that it is easy to advise the mother to pump her
milk while the baby is not breastfeeding, but this is not always easy in
practice and the mother may end up painfully engorged.
Breastfeeding and Maternal Medication
Most drugs appear in the milk, but usually only in tiny amounts.
Although a very few drugs may still cause problems for infants even in tiny
doses, this is not the case for the vast majority. Nursing mothers who are told
they must stop breastfeeding because of a certain drug should ask the physician
to make sure of this by checking with reliable sources. Note that the CPS (in
Canada) and the PDR (in the USA) are not reliable sources of information about
drugs and breastfeeding. Or the mother should ask the physician to prescribe an
alternate medication that is acceptable during breastfeeding. In this day and
age, it should not be a problem to find a safe alternative. If the prescribing
physician is not flexible, the mother should seek another opinion, but not stop
breastfeeding.
Why do most drugs appear in the milk in only small amounts? Because
what gets into the milk depends on the concentration in the mother’s blood and
the concentration in the mother’s blood is often measured in micro- or even
nano-grams per millilitre (millionths or billionths of a gram), whereas the
mother takes the drug in milligrams (thousandths of grams) or even grams.
Furthermore, not all the drug in the mother’s blood can get into the milk. Only
the drug that is not attached to protein in the mother’s blood can get into the
milk. Many drugs are almost completely attached to protein in the mother’s
blood. Thus, the baby is not getting amounts of drug similar to the mother’s
intake, but almost always, much less on a weight basis. For example, in one
study with the antidepressant paroxetine (Paxil), the mother got over 300 micrograms
per kg per day, whereas the baby got about 1 microgram per kg per day).
Most drugs are safe if:
• They are commonly prescribed for infants. The amount the baby would get
through the milk is much less than he would get if given directly.
• They are considered safe in pregnancy. This is not always true, since during
the pregnancy, the mother’s body is helping the baby’s get rid of drug. Thus it
is theoretically possible that toxic accumulation of the drug might occur
during breastfeeding when it wouldn’t during pregnancy (though this is probably
rare). However, if the concern is for the baby’s merely getting exposed to a
drug, say an antidepressant, then the baby is getting exposed to much more drug
at a more sensitive time during pregnancy than during breastfeeding. Recent
studies about withdrawal symptoms in newborn babies exposed to SSRI type
antidepressants during pregnancy somehow seems to implicate breastfeeding as if
this type of problem requires a mother not to breastfeed. (Good example of how
breastfeeding is blamed for everything.) In fact, you cannot prevent these
withdrawal symptoms in the baby by breastfeeding, because the baby gets so
little in the milk..
• They are not absorbed from the stomach or intestines. These include many, but
not all, drugs given by injection. Examples are gentamicin (and other drugs in
this family of antibiotics), heparin, interferon, local anaesthetics,
omperazole.
• They are not excreted into the milk. Some drugs are just too big to get into
the milk. Examples are heparin, interferon, insulin, infliximab (Remicade),
etanercept (Enbrel).
The following are a few commonly used drugs considered safe during
breastfeeding:
• Acetaminophen (Tylenol, Tempra), alcohol (in reasonable amounts), aspirin (in
usual doses, for short periods). Most antiepileptic medications, most
antihypertensive medications, tetracycline, codeine, nonsteroidal
antiinflammatory medications (such as ibuprofin), prednisone, thyroxin,
propylthiourocil (PTU), warfarin, tricyclic antidepressants, sertraline
(Zoloft), paroxetine (Paxil), other antidepressants, metronidazole (Flagyl),
omperazole (Losec), Nix, Kwellada.
Note: Though generally safe, fluoxetine (Prozac) has a very long half
life (stays in the body for a long time). Thus, a baby born to a mother on this
drug during the pregnancy, will have large amounts in his body, and even the
small amount added during breastfeeding may result in significant accumulation
and side effects. These are rare, but have happened. There are two options that
you might consider:
1. Stop the fluoxetine (Prozac) for the last 4 to 8 weeks of your
pregnancy. In this way, you will eliminate the drug from your body and so will
the baby. Once the baby is born, he will be free of drug and the small amounts
in the milk will not usually cause problems and you can restart the fluoxetine
(Prozac).
2. If it is not possible to stop fluoxetine (Prozac) during your pregnancy,
consider changing to another drug that does not get into the milk in
significant amounts once the baby is born. Two good choices are sertraline
(Zoloft) and paroxetine (Paxil).
• Medications applied to the skin, inhaled (for example, drugs for asthma) or
applied to the eyes or nose are almost always safe for breastfeeding.
• Drugs for local or regional anaesthesia are not absorbed from the baby’s
stomach and are safe. Drugs for general anaesthesia will get into the milk in
only tiny amounts (like all drugs) and are extremely unlikely to cause any
effects on your baby. They usually have very short half lives and are eliminated
extremely rapidly from your body. You can breastfeed as soon as you are awake
and up to it.
• Immunizations given to the mother do not require her to stop breastfeeding.
On the contrary, the immunization will help the baby develop immunity to that immunization,
if anything gets into the milk. In fact, most of the time nothing does get into
the milk, except, possibly some of the live virus immunizations, such as German
Measles. And that’s good, not bad.
• X-rays and scans. Ordinary X-rays do not require a mother to stop
breastfeeding even when used with contrast material (example, intravenous
pyelogram). The reason is that the material does not get into the milk, and
even if it did it would not be absorbed by the baby. The same is true for CT
scans and MRI scans. You do not have to stop for even a second.
What about radioactive scans?
We do not want babies to get radioactivity, but we rarely hesitate to
do radioactive scans on them. When a mother gets a lung scan, or lymphangiogram
with radioactive material, or a bone scan, it is usually done with technetium
(though other materials are possible). Technetium has a half life (the length
of time it takes for ½ of all the drug to leave the body) of 6 hours, which
means that after 5 half lives it will be gone from the mother’s body. Thus, 30
hours after injection all of it will be gone and the mother can nurse her baby
without concern about his getting radiation. But does all the radioactivity
need be gone? After 12 hours, 75% of the technetium is gone, and the
concentration in the milk very low. I think that waiting 2 half lives is
enough, for a material such as technetium. But:: Not all technetium scans
require stopping breastfeeding at all (HIDA scan, for example). It depends on
which molecule the technetium is attached to. In the first few days, there is
very little milk (though there is enough). In this situation it would be
unnecessary for the mother to stop breastfeeding after a lung scan, for
example. However, one of the most common reasons to do a lung scan is to
diagnose a clot in the lung. This can now be done better and faster with CT
scan, which does not require interrupting breastfeeding for even 1 second.
If you decide that interruption of breastfeeding is the best course to
follow, then express milk for several days in advance (if you have advance
warning about the test). Only occasionally is a radioactive scan so urgent that
it cannot be delayed for a few days.
Thyroid scans are different. Radioactive iodine (I¹³¹) is concentrated in milk
and will be ingested by the baby and it will go to his thyroid where it will
stay for a long time. This is definitely of concern. So, the mother will have
to stop breastfeeding? No, because often the test does not need to be done at
all. Differentiating postpartum thyroiditis from Graves’ Disease (the most
common reason for doing the scan in nursing mothers) does not require a thyroid
scan. Get more information from the clinic. If a scan needs to be done, it is
possible to do a thyroid scan I¹²³, which requires stopping for only 12 to 24
hours, depending on the dose given. Don’t forget to express milk in advance so
the baby can get it instead of formula.
Questions? (416) 813-5757 (option 3) or drjacknewman@sympatico.ca or my book Dr. Jack Newman’s Guide to Breastfeeding (called The
Ultimate Breastfeeding Book of Answers in the USA)
Handout #9a. You Should Continue Breastfeeding (1)
(Drugs and Breastfeeding). Revised January 2005
Written by Jack Newman, MD, FRCPC. © 2005