Over-the-Counter Lice Treatment May Not Be Effective

Overuse of permethrin/synergized pyrethrins has caused resistant head lice.

A recent study indicates that some treatments for head lice may not be as effective as they used to be.

Young, school-aged children are the most likely to develop a head lice infestation, but other factors can affect this, such as the amount of children in a household, sharing beds and clothing, socioeconomic status, and cleanliness of schools and other institutions. While head lice are not known to carry diseases or transmit infections, the infestation is commonly eradicated.

Over-the-counter treatments may be beneficial for some conditions such as heart disease or headache, but have shown to be harmful in others where resistance develops. Scientists have found that the efficacy of the over-the-counter treatments permethrin/synergized pyrethrins has declined due to resistance developed through widespread use, according to the study published by Pediatric Dermatology.

“Our findings indicate that over-the-counter treatments for head louse infestations are no longer likely to be effective,” said study co-author Terri Meinking, PhD.

They also discovered that the common treatment lindane may be toxic and should be avoided, however, there are alternative treatment options available.

Prescription products, such as malathion, benzyl alcohol, spinosad, and topical ivermectin, have all been shown to be safe and effective, according to the study. Other home remedies have not been proven to be safe or effective in eradicating the lice.

In fact, treatment with petroleum jelly, mayonnaise, and essential oils could potentially cause adverse reactions, according to the study.

"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,” said lead author Ellen Koch, PhD.