Morphine excretion in breast milk and resultant exposure of a nursing infant

J Toxicol Clin Toxicol. 1990;28(3):365-70. doi: 10.3109/15563659008994437.


We report the case of an infant who was breastfed while his mother was receiving low doses of morphine. Morphine concentration in his serum was in the analgesic range (4 ng/ml), while concentrations in the milk varied substantially in three samples collected within 2 hours (10, 100, 12 ng/ml). The calculated dose that the infant must have received to achieve the observed serum concentration had to be between 0.8 to 12% of maternal dose, based on reference literature values of clearance and bioavailability. The current perception that maternal morphine exposure is safe for the breastfed infant is based on a 50 year old data which were determined by an analytical method 1000 fold less sensitive than the present HPLC, thus leading to a likely erroneous conclusion.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Biological Availability
  • Breast Feeding*
  • Chromatography, High Pressure Liquid
  • Female
  • Humans
  • Infant, Newborn
  • Male
  • Milk, Human / chemistry*
  • Morphine / analysis*
  • Morphine / blood
  • Morphine / pharmacokinetics
  • Predictive Value of Tests


  • Morphine