The Best Will Permanent Hair Color Fade References. There are also different ingredients in some products, like those with an oil base — which are supposed to take longer to fade. Generally, permanent hair dye will last between four and six weeks.
Shampooing your hair too often. Permanent hair dye lasts until it grows out, but it might not always keep the exact same color. One of the first things you may start to notice as your hair color fades is noticeable root growth.
