Resistant head lice come about in a similar way to antibiotic-resistant bacteria. Head lice has been reported to have resistance to a range of popular chemical treatments. One of the most common causes of treatment failure is not the presence of resistant lice, but from not completing the full course of treatment. With most types of head lice treatment, multiple applications are needed to break the head lice life cycle. Learn what is resistant head lice, how it survives and how to kill them.