Hedrin’s efficacy is a result of its active ingredients, Dimeticone (contained in Hedrin 4% Lotion and Hedrin Once) and Activdiol (contained in Hedrin Treat & Go and Protect & Go). All formulations are patented and have been shown to be effective at killing head lice in clinical trials and even work on lice that have developed a resistance to traditional pesticide treatments.
Head lice have a unique strategy of water management. Instead of producing urine they eliminate excess water via tiny passages in their exoskeleton called spiracles. The active ingredient Dimeticone, a silicone oil, disrupts this process of water management by coating the lice, causing them to become permanently immobile, and blocking the spiracles preventing them from getting rid of excess water. As a result, any lice that have recently fed suffer from death by gut rupture and, the ones that haven’t, die of starvation.
Experiments carried out at the Medical Entomology Centre showed how Hedrin 4% lotion kills lice.
Like all insects, head lice are covered by a waxy protective coating. It is this waxy layer that helps the louse maintain its delicate internal water balance, preventing too much water from evaporating.
The Activdiol in Hedrin works dissolving away this waxy cuticle, causing death by dehydration.
Because Dimeticone and Activdiol kill lice with a ‘physical’ mode of action unlike a traditional chemical pesticide, you can use them as often as you like without the danger of the lice becoming resistant. Hedrin products are also free from solvents that can cause problems in some asthma sufferers.