Newer permanent and demipermanent hair dyes that have replaced PPD with para-toluenediamine sulfate (PTDS ... allergic to PPD will tolerate PPD-free hair dyes containing PTDS.

For example, sulfates are sometimes thought to be bad for hair—but not always. When we hear about a sulfate-free hair ... can also strip and dull your hair color, says Jennifer Korab, a ...

The PPD-free PTDS-based hair dyes were recommended to all 13 subjects of this study who were seen since January 2008. Ten of these 13 subjects used the recommended dyes, and none of these subjects ...