pyrethrin and piperonyl butoxide /pī″rəthrin, piper″ənil/ , a fixed-combination scabicide and pediculicide. ▪ INDICATIONS: It is prescribed in the treatment of infestations of head, body, and pubic lice. ▪ CONTRAINDICATIONS: Known hypersensitivity to chrysanthemums, ragweed, or this drug prohibits its use. ▪ ADVERSE EFFECTS: Among the more serious adverse effects are irritation of the skin and the mucous membranes.