Heinz body hemolysis following extended use phenazopyridine in a post‐HCT patient with hemorrhagic cystitis: An old problem for a new generation

Hemorrhagic cystitis is a common complication following the use of cyclophosphamide. Associated dysuria can be painful and there are few good options to relieve pain. Phenazopyridine has historically been utilized for dysuria and is available over the counter. However, it is associated with hematologic side effects with prolonged use. Here we present a case of a patient who developed Heinz body hemolysis following prolonged administration of phenazopyridine to treat cyclophosphamide‐induced hemorrhagic cystitis following hematopoietic stem cell transplant.