IPL is less effective on red, blonde, gray and white hair. This is due to the ratio of the melanin types eumelanin, which responds to IPL, and pheomelanin, which does not. - Dark blonde hair can respond to IPL, but results take longer. Light blond hair is not suitable. - Gray or white hair lacks melanin, which is why IPL does not work on these hair colours. - If the hair is red, it depends on the ratio between eumelanin and pheomelanin. See visual guides for blonde and red hair to assess whether the IPL is right for you here.