Povidone iodine is referred to as an iodophore, meaning that povidone acts as a carrier only for the elemental iodine it contains. Iodine is considered to be the active moiety that mediates the microbicidal activity. When released from the complex, free iodine rapidly penetrates the cell wall of microorganisms, and the effect is thought to result from disruption of protein and nucleic acid structure and synthesis. The exact mechanism at the molecular level is not fully understood.
Povidone-iodine is applied topically (on the skin) only. It is not used systemically and therefore no data on absorption, metabolism, excretion, etc. are available.
The iodine in PVP-I reacts with hydrogen peroxide, silver, taurolidine, and enzymes, rendering them (and itself) ineffective. It also reacts with many mercury compounds, producing the corrosive compound mercuric iodide, and with many metals, making it unsuitable for disinfecting metal piercings.