Piperonyl butoxide (PBO) is a pesticide synergist. It does not, by itself have pesticidal properties. However, when added to insecticide mixtures, typically pyrethrin, pyrethroid, and carbamate insecticides, their potency is increased considerably.[1]

PYRETHINS; PIPERONYL BUTOXIDE is used to treat lice infestations. It acts by destroying the lice, but it does not destroy their eggs (nits). This medicine may be used to treat head lice, body lice, or pubic lice.