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Update: Transfer of Drugs and Chemicals into Human Milk

Cheston M. Berlin, Jr., MD
from Breastfeeding Abstracts, August 2001, Volume 21, Number 1, pp. 3-4.

Pediatricians have enthusiastically supported the recommendation of the American Academy of Pediatrics that human milk is the optimal food for infants in their first year of life. It is recommended that human milk be the only food during the first six months and the only form of milk given to infants until one year of age.

Pediatricians are frequently asked by nursing mothers whether it is safe for them to take prescribed and/or over-the-counter (non-prescription) drugs while breastfeeding. Some mothers are instructed by the prescribing physician, usually not a pediatrician, not to breastfeed while taking a certain drug. Other mothers need to undergo either diagnostic or surgical procedures while breastfeeding, and they may ask questions concerning the use of diagnostic isotopes, anesthesia, and pain medication. The Committee on Drugs (COD) of the American Academy of Pediatrics recognized that it would be important to assemble information concerning the transfer of drugs and other chemicals into human milk and to make this information readily available to physicians.

Accordingly, the first statement that summarized what is known about medications and their appearance in human milk was published in 1983. Revisions have been published in 1989, 1994, and most recently, in the September 2001 issue of Pediatrics.

In assembling the information for this statement, the COD attempted to report the results of research involving measurement of specific compounds in milk and their possible effect on the nursing infant. Personal communications and anecdotal reports were not considered to be authoritative sources of information. The current statement, in addition to expanding the number of drugs which appear to be compatible with continued breastfeeding, also highlights three areas that have been widely discussed in relation to breastfeeding: cigarette smoking, psychotropic drugs, and silicone breast implants.

In the previous statement, the COD felt that cigarette smoking was specifically contraindicated during nursing, and even placed nicotine on the table entitled "Drugs of Abuse: Contraindicated During Breastfeeding." Since that statement was published, there has been some evidence that it may be safer for mothers who smoke to breastfeed than to bottle-feed. Therefore, the Committee felt it was prudent not to take a position on smoking and breastfeeding, but to emphasize to physicians that pregnancy and breastfeeding may be an excellent time in which to convince mothers to stop smoking.

The use of psychotropic drugs (tranquilizing agents, antidepressants, antipsychotic drugs) during lactation presents challenges to the physician caring for either the mother or the infant. It is recognized that postpartum depression and other types of psychological disturbance are seen frequently, and it is important to treat these conditions. The problem with using these drugs during lactation is that there are no long-term follow-up studies on the possible effect of psychotropic drugs on the neuropsychiatric development of the child. There have been a small number of case reports of some feeding and behavioral disturbances in infants under the age of one month whose mothers have been taking some of these medications. The drugs in these three categories all work by altering the action of receptors within the central nervous system. We know that young infants and children have rapidly developing brains and rapidly developing neuroreceptors, and the long-term consequences of possible interference with such neurotransmitters and receptors is unknown. Thus, psychotropic drugs are placed in the table which is entitled “Drugs Whose Effect is Unknown But of Concern.”

Breast implants continue to be widely used in this country, although in recent years saline implants are used rather than silicone ones. There was an initial report of esophageal dysfunction in the offspring of a small number of mothers who had silicone liquid implants. As a result there has been considerable controversy over the safety of implants and breastfeeding. The COD does not feel that there is persuasive evidence that nursing with implants is harmful to the child, and therefore silicone implants are not considered to be a contraindication to breastfeeding.

A small number of drugs have been associated with adverse events in the breastfeeding infant. These drugs should be used with caution, and where possible, a safer drug with therapeutic equivalence should be substituted (e.g., ibuprofen for aspirin; propanolol for atenolol). Table 6 of the statement contains a very large number of drugs whose use is thought to be compatible with breastfeeding, and references are given for each drug. Should questions arise about the use of a particular drug during breastfeeding, the physician can review the primary literature before making a decision. In certain therapeutic categories, some drugs are thought to be safer than others. For example, regarding beta-blocking agents, we know that atenolol has caused significant problems in a number of babies and therefore it would be safer for the mother to be placed on a beta-blocker which seems to be quite safe for breastfeeding, such as propranolol. There are four drugs mentioned in the table of cytotoxic drugs that may interfere with cellular metabolism of the nursing infant: cyclophosphamide, cyclosporine, doxyrubicin, and methotrexate. At the present time there is theoretical concern about the effect on the nursing infant of these compounds. The COD continues to feel that drugs of abuse are contraindicated in breastfeeding. This includes amphetamine, cocaine, heroin, marijuana, and phencyclodine. The use of radioactive compounds should not be contraindicated during breastfeeding as long as the mother is able to pump until all the radioactivity above background levels disappears from her milk. Since most of the commonly used diagnostic isotopes have a relatively short half-life, this may involve pumping for 24 to 48 hours.

It is hoped that the widespread availability of this statement will eliminate many of the situations where mothers are incorrectly told that they cannot breastfeed when taking a certain drug, even though further investigation would show that the drug probably does not interfere with either the infant’s health or the production of milk. A nursing mother should always inform her physician that she is lactating and discuss with the physician implications of drug therapy.

Cheston M. Berlin, Jr., M.D., is University Professor of Pediatrics, Professor of Pharmacology, and Chief, Section of General Pediatrics at the Milton S. Hershey Medical Center of the Pennsylvania State University College of Medicine. He is a long-standing member of the American Academy of Pediatrics and has served as Chairperson of the Committee on Drugs. Dr. Berlin is also a member of La Leche League International’s Professional Advisory Board and a board member of the International Board of Lactation Consultant Examiners.


The transfer of drugs and chemicals into human milk. Pediatrics 2001; 108:776-89.

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