 Eculizumab is used to treat atypical hemolytic uremic syndrome (aHUS) and paroxysmal nocturnal hemoglobinuria (PNH).For people with PNH, it improves quality of life and decreases the need for blood transfusions but does not appear to affect the risk of death.It does not appear to change the risk of blood clots, myelodysplastic syndrome, acute myelogenous leukemia, or aplastic anemia.