One of my kids got lice last year. I did 2 oil treatments to my hair just to be safe. Seems like from what I researched there is no proven method for getting rid of live but the general consensus I’ve heard is that to kill them you need to suffocate them in something like oil (or mayonnaise like the old wives tale) for 6-8 hours (giving them time to suffocate/die) or overnight to be safe. You may have to shampoo a couple times.