Back to school time sometimes means the frustration of dealing with head lice. Many parents find this is an exhausting and distressing undertaking.
Why Don’t OTC Treatments Kill Head Lice?
A comprehensive review of head lice treatments has found that most of the approved over-the-counter treatments based on permethrin and synergized pyrethrins are not very effective. Widespread use has allowed head lice to develop resistance to them.
The dermatologists suggest instead that doctors prescribe ivermectin (Sklice), malathion or spinosad (Natroba). All of these require only a single application to kill head lice and no nit combing. They discourage the use of lindane as too toxic and mayonnaise as ineffective.
Mineral Oil to Defeat Lice:
Although it has the dermatologists’ approval, we are queasy about the insecticide malathion. It is commonly used for mosquito control, but the International Agency for Research on Cancer has identified it as a probable carcinogen. Avoiding its use on the scalp seems like a reasonable precaution.
Other research shows, however, that a shampoo based on mineral oil is quite effective against lice (PLOS One, June 10, 2016). It was tested head-to-head against a pyrethrin-based product. It got rid of lice in 96 percent of the test subjects; 78 percent were still free of lice after 10 days.
The mineral-oil based shampoo is sold in various countries under the brand names Mosquito, Paranix or Silcap. As far as we know, it is not available in the US, but mineral oil is widely available at an affordable price. Because the mechanism of action is suffocation, plain mineral oil might work just as well as the shampoo to kill head lice. It won’t wash out of the hair quite as easily, however.
Another Prescription Option:
We don’t know why the dermatologists did not include benzyl alcohol in their review. This product, sold under the brand name Ulesfia, is approved by the FDA for treating lice infestations.