It can be very effective if part of a holistic process. On its own it does not guarantee 100% effectiveness. The Hairforce – Lice Assassins dehydrate the nits – the eggs – with controlled heated air using a very specialist machine after they have removed all the crawling head lice. Their machine is cooler than a hairdryer. If you used a hairdryer to do what they do you will burn the scalp. The controlled heated air device delivers an over 95% effectiveness rate, so to cover off that potential under 5% they remove all of the eggs and see you again 7 days later for a second forensic comb out.
With regards to the use of heat many people ask about hair straighteners – can you kill the lice and eggs with them? The problem is that the head lice are on the scalp and the fresh eggs are at the root so either way you will burn the scalp if you use them.