What is the role of 4% dimethicone lotion in the treatment of pediculosis and pthiriasis (lice infestation)?

Updated: Mar 01, 2018
  • Author: Lyn C C Guenther, MD, FRCPC, FAAD; Chief Editor: Michael Stuart Bronze, MD  more...
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One study reported efficacy of 4% dimethicone lotion (a silicone-based lotion believed to disrupt the louse's ability to manage water) in the treatment of head lice. [37] Another study found that 4% dimethicone lotion was a significantly more effective than malathion in most patients. [38] NYDA is a Canadian-approved product that contains 92% dimethicone. In one study, it was found to be superior to 1% permethrin lotion. [39] The dimethicone in NYDA replaces the air in the breathing system of lice, nymphs, and nits (eggs) and then thickens quickly, causing suffocation and death. NYDA is approved in Canada for use in individuals aged 2 years or older. This product should eliminate head lice infestations after one application; however, the product monograph recommends a second treatment to ensure complete removal of head lice.

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