In general, hair dye will not lighten already colored hair. To lighten your hair, you must not only wait for the hair molecules to decrease, but you may also need to "strip" away your hair undertone, depending on how light you want to go. There are several ways to do this: First, you can use a perm solution to raise the lowered value of your hair. Then, use a shampoo-type product to remove any residual chemicals from previous treatments. If you choose this route, be sure to find a product with a low pH (i.e., not too acidic or too basic) since you will be exposing your hair to more alkaline conditions than normal. You should also use a product that contains an amino acid such as cysteine or glycine since these components help prevent hair loss. Finally, it's important to use caution not to overdo it when stripping hair of its color; if you use a strong oxidizing agent, such as peroxide, you could end up burning the hair shafts instead of just stripping them of their color. Once you've stripped your hair of its color, you can then proceed with another treatment. Of course, this depends on what kind of color you're trying to lighten...if you wanted to lighten to a very dark shade, you would have to start with a much lighter color than if you were just looking to lighten one color to another.