Povidone-iodine is also efficient against fungi and viruses (including HIV and "Herpes simplex"). It is used in pleurodesis (fusion of the pleura because of incessant pleural effusions). For this purpose, povidone-iodine is equally effective and safe as talc, and may be preferred because of easy availability and low cost. There is tentative evidence that chlorhexidine and denatured alcohol used to clean skin prior to surgery is better than povidone-iodine with alcohol; however, the evidence is not strong enough as of 2015 to determine routine practice. PVP-I is contraindicated in patients with hyperthyroidism (overactive thyroid gland) and other diseases of the thyroid,
Iodine the iodyl cation, [IO], and is reduced by concentrated sulfuric acids to iodosyl salts involving [IO]. It may be fluorinated by fluorine, bromine trifluoride, sulfur tetrafluoride, or chloryl fluoride, resulting iodine pentafluoride, which also reacts with iodine pentoxide, giving iodine(V) oxyfluoride, IOF. A few other less stable oxides are known, notably IO and IO; their structures have not been determined, but reasonable guesses are I(IO) and [IO][IO] respectively. More important are the four oxoacids: hypoiodous acid (HIO), iodous acid (HIO), iodic acid (HIO), and periodic acid (HIO or HIO). When iodine dissolves in aqueous solution, the following reactions occur: Hypoiodous