Mayonnaise works to kill head lice by way of suffocation. Head lice need to breathe and mayonnaise and some other oils are thick enough to coat their airways and suffocate them if left on the hair long enough. This is a 100% effective treatment method if executed correctly.

Does putting mayonnaise in your hair kill lice?

The United States version of the television series “The Office” may have popularized the use of mayonnaise to treat lice. There is no evidence that mayonnaise can kill or treat lice.

How long should Mayo stay in hair to kill lice?

Suffocation takes 6-8 hours. That means to eliminate lice using the mayonnaise method, you have to leave it in your hair for eight hours in order for suffocation to work.