While use of lithium in breastfeeding mothers is often discouraged, researchers at Massachusetts General Hospital in Boston found that lithium levels in breastfeeding infants were quite low and well tolerated.

According to Dr. Adele Viguera, “In clinical practice, use of lithium during lactation has been discouraged and typically considered contraindicated in breastfeeding.”

“These cautious recommendations arise from concerns that lithium may be secreted at high levels in breastmilk and infants may inefficiently clear lithium, thereby increasing their risk for significant drug exposure and toxicity,” said Dr. Viguera.

In an effort to quantify lithium exposure in breastfeeding infants, Dr. Viguera and her colleagues measured lithium levels in maternal serum and breastmilk and infant serum, in 10 mother-infant pairs.

Results of the study, published in the February issue of the American Journal of Psychiatry, found no evidence of growth or developmental delays. Given the small sample size, researchers caution that “taking lithium while breastfeeding should be considered appropriate only for carefully selected women with bipolar disorder.”