Yes, Just for Men hair color will work on any hair color. If you want to change your blonde hair to another color, the only thing you need to worry about is whether they have the hair color you want.
Yes It will. Although Just for Men haircolor is designed to cover up gray hairs it is still a colored hair dye and will alter the color of your hair. This is especially true for blonde hair as the pigmentation is light so it is more easily tinted by dyes.
