The results of ingredient patch testing in contact dermatitis elicited by povidone-iodine preparations

10 cases of contact dermatitis which began during the application of povidone-iodine preparations were examined with patch tests using 2 kinds of povidone-iodine preparations and their ingredients, i.e., povidone-iodine, polyoxyethylene nonylphenyl ether and glycerin, and also the components of povidone-iodine, i.e., iodine and polyvinylpyrrolidone. All 10 cases reacted positively to the povidone-iodine preparations and povidone-iodine, 3 out of thr 10 to polyoxyethylene nonylphenyl ether, 1 out of the 9 tested to iodine, while no positive response was found to glycerin or polyvinylpyrrolidone. It was difficult to distinguish between allergic responses from irritation, as responses to patches of povidone-iodine and its preparations usually include irritation at high frequencies. Based on comparison of results with a control group, however, those showing + or stronger reactions to 2% povidone-iodine at days 3 to 5 were considered to be allergic. Thus, 4 out of the 10 cases were considered as sensitization to povidone-iodine. Another 3 cases were found to be polyoxyethylene nonylphenyl ether sensitized, and another 1 iodine sensitized, while the patch test reactions of the other 2 were considered to have been elicited by irritation.