Although amounts of chlorthalidone in milk are not great, its slow clearance may lead to accumulation in the infant, especially while nursing a newborn or preterm infant. It may also suppress lactation. An alternate drug may be preferred.

Because no information is available on the use of reserpine during breastfeeding and it might adversely affect the breastfed infant, an alternate drug may be preferred, especially while nursing a newborn or preterm infant.