Hello, Welcome, and thanks for sharing your concern I went through your query, and I feel, There are at least a dozen different chemicals in hair dye that can cause a severe allergic reaction The chemical P-phenylenediamine (or PPD) is used to ensure the color you use stays bright and shiny through several washings. However, it has also been shown to cause skin blistering, burning, and rash. The colour of dye on the fingers will fade with time or you need to check the package of the dye to see if it has instructions on that. I hope my advice would have been useful, in decision making regarding your treatment, still if you have any clarifications or doubts feel free to contact back. Thanks.