It makes me sad when a mom tells me, "I really wanted to breastfeed, but my doctor said I couldn't because of a medication I have to take." Sometimes, in very rare cases, the medication may truly be incompatible with breastfeeding. Certain drugs like Lithium, argatroban, any type of radioactive iodine, any chemotherapy agent and a handful of other drugs are definitely not safe for a nursing baby.
However, many medications that may be acceptable come with a manufacturer's label discouraging use by nursing women. Why is this? Perhaps it is an attempt by the drug manufacturers at CYA (just in case something were to happen....) Perhaps a drug may not be safe for use during pregnancy, so the assumption is made that it isn't safe during lactation either.
Whatever the case, many health care practitioners are quick to tell a mother that they can't continue breastfeeding while taking a certain medication, even if the evidence does not bear that out. Ideally, it really is best to limit the medication a breastfeeding mother takes to only what is truly necessary. But when a mother needs a particular medication to be healthy, she should certainly take it!
Dr. Thomas Hale, Ph.D. has devoted much of his career as a pharmacist to studying the effects of various medications on breastfed babies and on the breastmilk itself. He is a professor of Pediatrics at the Texas Tech University School of Medicine. Dr. Hale, who is widely recognized as the leading authority in this field, has authored a book called Medications and Mothers' Milk which is now in its thirteenth edition. Any health care provider who works with nursing mothers and babies should have a copy of this book to use as a reference.
Dr. Hale defines the following categories for lactation risk when considering a particular drug:
L1 - Safest - These drugs have been taken by many breastfeeding women with no adverse effects. Controlled studies fail to demonstrate a risk to a nursing infant, and the possibility of harm to the breastfeeding infant is remote, or the substance is not orally bioavailable to the infant.
L2 - Safer - These drugs have either been studied in a limited number of breastfeeding women without any increase in adverse effects in their infants or there is scant evidence of a demonstrated risk likely to result as a use of these medications.
L3 - Moderately Safe - There are no controlled studies in breastfeeding women; however, there is a possibility of a risk. Or controlled studies that do exist may show only minimal non-threatening adverse effects. These drugs should be used only if the potential benefit justifies the potential risk to the infant.
L4 - Possibly Hazardous - Positive evidence exists showing a risk either to the breastfed infant or to the mother's milk production; however, the benefits from the use of the drug may be acceptable despite the risk to the infant (e.g., if the drug is needed in a life-threatening situation or for a serious disease for which a safer drug does not exist or is not effective.)
L5 - Contraindicated - Studies in breastfeeding mothers have demonstrated that there is significant and documented risk to the infant, or it is a medication that has a high risk of causing significant damage to the infant. The risk of using these drugs in nursing mothers absolutely outweighs any possible benefit from breastfeeding.
The next time you are faced with needing a medication, be sure to ask your doctor to check Dr. Hale's book. If he doesn't have it, find a lactation consultant who does, and do your research! There's no need to stop breastfeeding unless you absolutely have to!