How does dimethicone work against lice? - briefly
Dimethicone forms a thin, airtight layer over lice and their eggs, blocking their breathing pores and causing suffocation. The coating also weakens the grip of nits, facilitating mechanical removal.
How does dimethicone work against lice? - in detail
Dimethicone, a silicone‑based polymer, eliminates head‑lice infestations primarily through physical rather than chemical action. When applied to the scalp, the fluid spreads across hair shafts and creates a thin, continuous film that adheres to the insects’ exoskeleton. This coating interferes with the lice’s ability to exchange gases, effectively suffocating them. The polymer also disrupts the surface tension of the cuticle, causing loss of moisture and leading to rapid dehydration.
Key aspects of the action include:
- Occlusive barrier – a non‑penetrating layer that blocks spiracles, the breathing openings on the insect’s abdomen.
- Desiccation – the silicone film draws water away from the body and eggs, preventing rehydration.
- Mechanical immobilization – increased viscosity reduces the lice’s mobility, making it difficult for them to cling to hair or crawl.
- Egg (nits) prevention – the coating adheres to the cement that attaches nits to hair shafts, weakening the bond and facilitating removal during combing.
Because the effect is physical, dimethicone does not rely on neurotoxic pathways, which eliminates the risk of resistance that commonly develops with conventional insecticides. Its inert nature also minimizes irritation to human skin and reduces the likelihood of allergic reactions.
Effective use requires thorough saturation of the hair and scalp, a waiting period of 10–15 minutes to allow the polymer to coat the insects, followed by a fine‑toothed nit comb to extract dead lice and loosen detached nits. Re‑treatment after 7–10 days targets any newly hatched lice that escaped the initial application.
Safety data indicate low systemic absorption; the compound remains on the surface and is removed with shampoo. Regulatory agencies approve it for over‑the‑counter lice treatment, provided instructions for dosage and exposure time are followed.