It belongs to a class of drugs known as pyrethrins. Permethrin works by paralyzing and killing lice and their eggs (nits).

Does pyrethrin kill nits?

Pyrethrins are safe and effective when used as directed. Pyrethrins can only kill live lice, not unhatched eggs (nits). A second treatment is recommended 9 to 10 days after the first treatment to kill any newly hatched lice before they can produce new eggs.

Will pyrethrum kill lice?

Pyrethrin and piperonyl butoxide shampoo is used to treat lice (small insects that attach themselves to the skin on the head, body, or pubic area [‘crabs’]) in adults and children 2 years of age and older. Pyrethrin and piperonyl butoxide is in a class of medications called pediculicides. It works by killing lice.