I have a lot of grey hair. I had no problems using the standard hair coloring shampoos and gels. Then suddenly during one application I developed a very strong allergic response. Since then I have not been able colour my hair. The standard hair coloring stuf contains Paraphenylenediamine which is what makes the color permanent and easy to use. Does anyone know of any alternative that I can use? I have black hair and applying henna was suggested by someone, but that is quite a cumbersome and messy process and the results do not give a black color. Anything else? Biodyes, all natural products?