This is an important question and there is no right or wrong answer on how long to wait. Speak to your paediatrician for advice. Overall, the active metabolite of spironolactone (known as canrenone) does appear in breast milk. Studies estimated that 0.2% of the mother's total daily dosage in the form of canrenone would be in breast milk. After about 10 days, most of the drug would be out of your body given the half life of canrenone being about 10 -12 hours.When we think about the safety of medications during breastfeeding, we turn to the Hale Rating Score for helpful advice. It rates drugs on a scale from L1 to L5 - with L1 being safest and L5 being hazardous. The Hale Rating Score for Spironolactone is "L2". An L2 rating meats that the drug has has been studied in a limited number of breastfeeding women without an increase in adverse effects in the infant; And/or, the evidence of a demonstrated risk which is likely to follow use of this medication in a breastfeeding woman is remote.The 2001 report of the American Academy of Pediatrics titled " The Transfer of Drugs and Other Chemicals Into Human Milk" gave spironolactone a low risk profile and placed it in the category "Maternal Medication Usually Compatible With Breastfeeding". Overall, speak to your paediatrician. You are very wise to consider these risks, but it is low. Together you and your paediatrician can determine what waiting period is best for you. Spironolactone can suppress lactation in many women as well so there could be a delay in resuming breast feeding as well. Keep in mind as well in your decision making that spironolactone is sometimes used for infants with heart failure - at much higher doses than would even be in breast milk. Thank you.Reference1. Phelps DL, Karim A. Spironolactone: relationship between concentrations of dethioacetylated metabolite in human serum and milk. J Pharm Sci. 1977;66:1203. PMID
