Long-term
PNH is a chronic condition. In patients who have only a small clone and few problems, monitoring of the flow cytometry every six months gives information on the severity and risk of potential complications. Given the high risk of thrombosis in PNH, preventative treatment with warfarin decreases the risk of thrombosis in those with a large clone (50% of white blood cells type III).
Episodes of thrombosis are treated as they would in other patients, but given that PNH is a persisting underlying cause it is likely that treatment with warfarin or similar drugs needs to be continued long-term after an episode of thrombosis.

Acute attacks]
There is disagreement as to whether steroids (such as prednisolone) can decrease the severity of hemolytic crises. Transfusion therapy may be needed; in addition to correcting significant anemia this suppresses the production of PNH cells by the bone marrow, and indirectly the severity of the hemolysis. Iron deficiency develops with time, due to losses in urine, and may have to be treated if present. Iron therapy can result in more hemolysis as more PNH cells are produced.
A new monoclonal antibody, eculizumab, protects blood cells against immune destruction by inhibiting the complement system. It has been shown to reduce the need for blood transfusion in patients with significant hemolysis.