Yes, hair dryers will kill lice. It is difficult to do because you have to get the heat down to the scalp and work through very methodically to make sure you get every live louse before it can move from a hot section to a cooler section and dry out every nit. Be careful because it is easy to burn the scalp if the hair dryer is left in one spot for too long. For best results on your own, use a hair dryer and a lice kit and comb through with a high-quality lice comb. Otherwise, hiring a professional will be faster and safer.