The concentrations of methadone found in human milk are low, and that women on stable doses of methadone maintenance should be encouraged to breastfeed if desired, irrespective of maternal methadone dose. Providers should ensure that the mothers are receiving the methadone through an approved methadone maintenance program and receive routine screening for other substances, and found to be free of all other substances of abuse. The low dose of methadone in the breastmilk will not prevent symptoms of withdrawal but might lessen them in some infants.
Academy of Breastfeeding Medicine Clinical Protocol #21: Guidelines for Breastfeeding and Substance Use or Substance Use Disorder, Revised 2015.