There is very limited information on the use of sulfonylureas during breastfeeding. However, information that is available suggests that most sulfonylureas will be found in negligible amounts in the breast milk. There are no reports of hypoglycaemia in infants due to sulfonyureas in breast milk. Infant monitoring for signs of hypoglycaemia, and period infant blood glucose levels, are an option, especially with drugs with less evidence and in very young infants.
Acting Co-Director, West Midlands Medicines Information Service & UK Drugs in Lactation Advisory Service