October 05, 2016
1 min read

Over-the-counter head lice treatments lose efficacy; judicious use of prescription drugs advised

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Ellen Koch

Pyrethroid head lice treatments have decreased in efficacy during the past 30 years, likely because of indiscriminate and widespread use, according to recent study findings.

“In the United States, filling of prescriptions for the treatment of [lice] infestations had a seasonal peak in July to September for 2012 to 2014, coinciding with the back-to-school period,” Ellen Koch, MD, of the pediatric department at the University of Pittsburgh Medical Center, and colleagues wrote. “There has been an increase of approximately 4% in prescriptions over each prior year, possibly because of more infestations or more infestations failing nonprescription over-the-counter or home remedy approaches.”

To address the need for health care provider awareness on appropriate and cost-effective management for head lice infestations, Koch and colleagues conducted a review of three biomedical databases on lice treatments available in the U.S. from 1985 to the present. Embase, Medline and Chemical Abstracts were searched from September 2012 to 2014, and additional PubMed searches were conducted through October 2015.

The review produced 579 references for head lice treatment. Recent clinical studies revealed a decline to 25% effectiveness for permethrin and synergized pyrethrins (collectively pyrethroids), suspected from overuse in the national population. In addition, lindane was found to have a high toxicity level.

“Our findings indicate that over-the-counter treatments for head louse infestations are no longer likely to be effective,” researcher Terri L. Meinking, PhD, president of Global Health Association of Miami, said in a press release.

The researchers also noted that home remedies such as oil and mayonnaise are ineffective and have the potential to cause severe adverse reactions.

The availability of safe and effective prescription treatments, however, such as malathion, benzyl alcohol, spinosad and topical ivermectin achieved an estimated effectiveness of 90% or greater, Koch and colleagues wrote.

“The lesson we should learn is that those products that do remain effective, which are available by prescription, should be used judiciously so that they do not suffer the fate that has befallen the pyrethroids,” Koch said in the release. – by Kate Sherrer

Disclosure: The researchers report no relevant financial disclosures.