Resistant Head Lice

Permethrin resistant head lice have been reported from France, England, and Israel (Lancet 344: 1724, 1994)

In Virginia, there has also been a problem with Nix^TM resistant lice. In its place, lindane or Kwell has worked well.

The warning issued by the FDA about Kwell referred to overuse, especially in infants. It appears that widespread use of any single medicine may lead to resistance in any one geographic area, so that rotation of pediculicides may be a good strategy.

COMMENT: This makes good scientific sense, in light of what we know about the rise of bacterial and parasite resistance. However, head lice is such an emotional problem and so many nonscientific organizations influence decisions, that it might be difficult to use Kwell, even though it is still effective.

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