Feb. 25, 2010 -- A new prescription lotion that treats head lice is highly effective at killing the tiny bugs and is safe for children as young as 6 months, a study shows.
The medication -- benzyl alcohol lotion 5% -- is sold under the brand name Ulesfia. The study shows it works by suffocating lice, a method that has long been tried with limited success using messy substances like petroleum jelly, olive oil, and mayonnaise.
The lotion keeps the entry points that lice need to breathe open, causing the bugs to die from suffocation, researchers say. It is made of mineral oil and other inactive ingredients.
Overnight "home remedies" such as mayonnaise merely appear to kill lice, but don't because the bugs are able to close their spiracles long enough to survive. This is called the "resurrection effect" because, after rinsing, the lice thought to be dead are able to open their breathing spiracles and start biting again. But researchers say Ulesfia doesn't allow that to happen.
It also doesn't contain any pesticides, as many other treatments do. "Existing over-the-counter head lice treatments contain neurotoxic pesticides as active ingredients, resulting in potential toxicity and other problems, including lengthy applications, odor" and ineffectiveness, says study researcher Terri Meinking, PhD, president of Miami-based research firm Global Health Associates.
In addition, lice exposed to such products may become resistant to them "just as bacteria have become resistant to many antibiotics," Meinking says in a news release. "Because benzyl alcohol lotion kills by suffocation, resistance should not be an issue."
The studies involved more than 250 children, some of whom were treated with the benzyl alcohol lotion, and others with RID (a popular pesticide treatment) or the inactive lotion ingredients. In the studies comparing Ulesfia and RID, success rates were comparable.
The success rate (no live lice) was up to 92% one day after a second treatment in kids treated with Ulesfia. Two weeks after the second treatment, there was a 75% treatment success rate. The researchers write that reinfestation, rather than failed treatment, was more likely the reason.
The medication was approved by the FDA in 2009. The study is published in the January-February issue of the Pediatric Dermatology.
The study did not disclose the source of the researchers' funding.