Some anti-psychotics meds can cause agranulocytosis that can lead to fatal infections usu. occur within the 1st few months of the treatment.

Therefore,
Clozapine required weekly WBC monitoring for the 1st 6mo. of the therapy, every two weeks for the next six months, and monthly thereafter
 Stop the meds should wbc drop below certain levels.


Other meds include: Olanzapine & chlorpromazine

(1): http://www.aafp.org/afp/2010/0301/p617.html