Lice v. OTC Treatments

New evidence has emerged showing that head lice have developed resistance to two types of insecticides that are commonly used in over-the-counter (OTC) treatments for lice infestation, according to a study published in Journal of Medical Entomology (JME), as reported by ParaPRO,a  specialty pharmaceutical company that is leading research into new antiparasitic formulations.
 
The study, Expansion of the Knockdown Resistance Frequency Map for Human Head Lice (Phthiraptera: Pediculidae) in the United States Using Quantitative Sequencing, was designed to determine the extent and magnitude of the knock-down resistance (kdr)-type mutations responsible for the increasing prevalence of head lice resistant to common treatment formulations. Between July 22, 2013 and May 11, 2015, lice were collected from 138 collection sites in 48 U.S. states and analyzed by quantitative sequencing.
 
Findings showed that, on average, 98% of head lice in at least 42 states have developed gene mutations that make them resistant to various pyrethrins and pyrethroids, including permethrin, which is the active ingredient in popular treatment formulations for pediculosis.
 
“This newly published data supports what we've been seeing in our offices and clinics: an increase in treatment-resistant super lice,” said Chris Belcher, M.D., Peyton Manning Children's Hospital at St. Vincent, Indianapolis, IN. “It's important that parents contact a clinician if they suspect their child has head lice. There are effective, non-pyrethrin, non-pyrethroid-based prescription agents that can be used if treatment with over-the-counter products such as Nix®has been unsuccessful.”
 
Patient self-diagnosis and misuse of over-the-counter treatment options have contributed significantly to the increase in treatment-resistant head lice. Studies have shown that when self-treating with OTC products, as many as 69% of  people admit to using more than the recommended dose in an attempt to increase effectiveness. For example, most OTC products recommend two applications for treatment of head lice; however, some data suggest that patients self-treat an average of five times before seeking care from a healthcare provider. OTC lice medications are safe when used properly, but misuse could result in side effects such as skin rashes, asthma-like symptoms, and respiratory reactions like rhinitis, swelling of the mouth and larynx, coughing and wheezing