Hedrin's effectiveness is a result of its ingredients, Dimethicone Hedrin Hedrin's formulations are patented and have proven effective in killing lice and their eggs (nits) in clinical studies Dimethicone Lice have a unique water management strategy. Instead of producing urine, they eliminate excess water through tiny passages in their exoskeleton called spiracles. The active ingredient Dimethicone, a silicone oil, disrupts this water management process by coating the lice, causing them to become permanently immobile and blocking the coils, preventing them from getting rid of excess water. As a result, any aphids that did not die die of starvation. Actividol® Like all insects, lice are covered with a waxy protective coating. It is this wax layer that helps the louse maintain its delicate internal water balance, preventing it from evaporating. The actividol in Hedrin dissolves this waxy cuticle, causing death from dehydration. Activiol is available in treatment strength (5%) or protection strength (1%). Isononyl Isononanoate This ingredient has two modes of action which makes it important in dealing with lice and nits. Isononyl isononanoate has degreasing properties that cause the louse to die by dehydration. It also has the ability to loosen the bond between the hair and the nit which helps in removing nits from the hair.