henna products can contain hidden chemical impurities including metal salts like lead acetate, which can react poorly when used on hair that was previously colored with mainstream hair dyes and bleaches
A metallic salt will coat your hair similar to your conditioner, but will a lot harder to remove and often contains chemical stripping. Chemical stripping is normally done by salons and can be extremely pricey and overall damaging to your hair. the safest removal method is to grow your hair out and slowly trim or BC. Metallic salts are not only present in artificial dyes such as henna, but also in most dyes that are available in local grocery stores. Be sure to read the label before purchasing ANYTHING that may contain metallic salts.