Kidney failure occurs when the kidneys cannot remove waste products from the blood or control the amount of water in your body. Acute kidney failure occurs suddenly and may be the result of injury, loss of large amounts of blood, drugs or poisons. Kidneys may return to normal function if they are not too badly damaged. Chronic renal failure means a slow decline in kidney function, which may not be noticed immediately. If renal function continues to deteriorate dialysis may be needed.