Introduction:
Methemoglobinemia is considered a rare and serious disorder of the blood
and if left untreated can be fatal. Methemoglobinemia is defined as an
increase in methemoglobin levels in the blood. The underlying mechanism
includes changing the hemoglobin heme iron from a ferrous to a ferric
state and eventually may lead to decrease oxygen delivery to the
tissues. Methemoglobinemia can be congenital or acquired due to toxins
or drugs. There are few reports of methemoglobinemia induced by
traditional dosing of SMX/TMP. However, in our case, methemoglobinemia
occurred within three days from the initiation of a high dose of SMX/TMP
with a rapid resolution of methemoglobinemia after discontinuation of
SMX/TMP.