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Breastfeeding and Drugs

Though many drugs are quite safe for a mother to take while nursing her child there are several agents for which safety during breast-feeding is not well-defined and may be a risk to the infant. Drugs that are contraindicated or should be used with caution by lactating women are described here.

Drugs Usually Contraindicated While Breastfeeding

Antineoplastics and Immune Suppressants
Even if small amounts of the drug were to be excreted into milk, the inherently toxic nature of these medications warrants caution with their use.

Ergot Alkaloids
Due to the dopaminergic activity of the ergot alkaloids they may have the ability to suppress prolactin and hence lactation. If breast-feeding is to be considered, milk volume must be monitored in mothers. Bromocriptine is used therapeutically to prevent lactation and is therefore contraindicated in nursing mothers. Short term, low dose therapy with ergonovine and methylergonovine does not cause a risk to the infant. However, methylergonovine would be the preferred choice of the two because is does not have prolactin lowering tendencies. Ergotamine is also able to affect milk secretion and is not a preferred choice while nursing because of the risk of ergotism in the infant. Signs of toxicity in the infant include vomiting, weight loss and weak pulse.

Infants should be closely monitored if breast-fed during maternal gold therapy as the exact effect on infants is not known at this time. Reported milk levels vary widely and aurothiomalite has been measured in both urine and plasma of infants.

Iodine containing compounds are not generally recommended during breast-feeding. Iodine readily gains access to breast milk and can lead to hypothyroidism in the infant.

Lithium Carbonate
Breast-feeding during maternal lithium therapy is generally thought to be contraindicated because lithium has been found to attain concentrations in the milk of up to 40% of the maternal weight adjusted dose. Moreover, the excretion of lithium in milk appears to vary a great deal among patients. Since some women will have relatively low excretion of lithium into their milk, and breast-feeding can be extremely beneficial to a manic depressive mother it seems quite reasonable to initiate breast-feeding. It is recommended that infants' serum lithium concentrations be monitored and the infant be observed for signs of toxicity. Breast-feeding may be continued as long as infants' blood levels remain well below therapeutic concentrations and the infant shows no signs of toxicity.

Radioactive materials are contraindicated while breast-feeding, in order to avoid excess infant exposure to radioactivity. Once radioactivity is cleared from the mother's body, however, breast-feeding can be resumed. The length of time of breast-feeding interruption will vary with each radioisotope used depending on radioactive decay and elimination by the mother. Motherisk can be consulted regarding this length of time.

Social Drugs and Drugs of Abuse
Alcohol freely distributes into milk and will be ingested by nursing infants. Moderate, occasional alcohol consumption in not likely to pose a problem to the infant, but heavy alcohol consumption is to be avoided. Ideally nursing should be withheld temporarily after alcohol consumption; at least two hours per drink to avoid unnecessary infant exposure. Side effects reported in infants include sedation and impairment of motor skills.

Cigarette smoking is not recommended in nursing mothers. Nicotine and its major metabolite are detectable in milk. Smoking should be avoided while breast-feeding because it has been associated with infantile colic, lowered maternal prolactin levels and consequently, earlier weaning.

Street drugs can be very potent such that even very small amounts can have pharmacological activity and adverse effects on the infant. It is suggested that breast-feeding be at least temporarily delayed after maternal use of these agents and caution should be used to avoid infant exposure to smoke fumes. Infants may experience toxicity after maternal cocaine use,and marijuana use has been associated with slower motor development at one year of age.

Myla Moretti, Motherisk

Motherisk Research

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The information on this website is not intended as a substitute for the advice and care of your doctor or other health-care provider. Always consult your doctor if you have any questions about exposures during pregnancy and before you take any medications.

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