I've heard about strains of head lice that are resistant to some over-the-counter lice treatments. What's the risk of my child getting infected with these "super lice," and what's the best way to treat them?

Answers from James M. Steckelberg, M.D.

Treatment-resistant head lice aren't a new problem. Dubbed "super lice," these lice are simply head lice that are becoming more resistant to the active ingredients in many common head lice treatments.

Unless resistance has been seen in the community, medications containing 1 percent permethrin or pyrethrins should be the first choice of treatment for active lice infestations. It's important to understand that although some over-the-counter (OTC) treatments may no longer be as effective as they once were, these first line treatments still work the majority of the time when used correctly.

Common reasons head lice treatments may not work include:

  • Not using the treatment correctly. Reapplying the treatment too soon, too late or not at all may result in continuous infestation. Follow treatment instructions carefully.
  • Misdiagnosis. What appears to be a lice infestation may actually be dandruff, scabs or clothing fibers. An itchy scalp may be a sign or symptom of dry skin or another skin condition.
  • Reinfestation. Although you or your child may have been treated correctly, you or your child may become infested again from another infested person.

If the correct use of an OTC treatment has failed and you're still finding lice and their eggs, your health care provider may prescribe a stronger treatment regimen, as this may be a sign of treatment-resistant head lice.

A number of home or natural remedies are used to treat head lice infestations, but there is little to no clinical evidence of their effectiveness.

For parents looking at alternative treatment methods, the Lice Clinics of America uses a Food and Drug Administration-cleared machine that uses one application of hot air in an attempt to kill head lice and their eggs through dehydration. The machine requires special training and is currently available only at professional lice treatment centers. A regular hair dryer should not be used to accomplish this result as it’s too hot and could burn the scalp. The machine uses air that is cooler than most hair dryers and at a much higher flow rate to kill the lice by drying them out.

March 23, 2016 See more Expert Answers