Breastmilk levels of nitroprusside sodium have not been measured after exogenous administration. Because of its short half-life of 2 minutes, it is unlikely to appear in breastmilk. However, its toxic metabolite, thiocyanate, is excreted into milk and can be directly toxic to the infant as well as inhibiting iodide transport into breastmilk. Cyanide is another toxic metabolite of nitroprusside that may enter breastmilk. An alternate drug is therefore preferred during breastfeeding. If use of nitroprusside sodium is unavoidable, the mother should refrain from breastfeeding.