Iron is an essential nutrient, but carries potential risks. Iron therapy not only affects the functions of leukocytes, endothelial cells, and cytokine production, but also causes oxidative stress and can support bacterial growth. Intravenous iron therapy may result in nontransferrin-bound iron. This may act as a catalytic agent in the formation of hydroxyl radicals, and thus potentially contribute to cell damage and atherosclerosis. Potential long-term complications of intravenous iron therapy in end-stage renal disease patients include atherosclerosis and infection, particularly in patients with iron overload.