Isoetharine is no longer marketed in the US. Although no published data exist on the use of isoetharine during lactation, data from the related drug, terbutaline, indicate that very little is expected to be excreted into breastmilk.[1-3] The authors of several reviews and an expert panel agree that use of inhaled bronchodilators is acceptable during breastfeeding because of the low bioavailability and maternal serum levels after use.[4-7]