Allergic contact dermatitis from povidone-iodine: a re-evaluation study.

500 consecutive patients were patch tested with a 10% povidone-iodine (PVP-I) solution, diluted 10 times in water. Readings were made at 2 and 4 days. 14 of the 500 (2.8%) showed a positive test to PVP-I. The 14 positive patients to PVP-I were subjected to a repeated open application test (ROAT) with a PVP-I solution, as is; 2 of the 14 were recorded as positive. It was concluded that only 2 of the 500 patients had true allergic contact dermatitis from PVP-I (0.4%). This study emphasizes the need for more complete investigation, when testing with some allergens, when they share both irritant and allergenic properties, such as PVP-I. The approach is important to rule out false-positive patch test reactions and to assess true clinical relevance.