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Head lice are a universal human parasite affecting more than 100 million people worldwide annually, including up to 12 million manifestations in the United States. Those most likely affected in developed nations are children aged 3 to 11 years. Over-the-counter (OTC) treatments are frequently employed improperly, and the social stigma associated with lice can make patients reluctant to see a health care professional. Infestations are frequently misdiagnosed. In one study of head lice diagnosis accuracy, just 53% of materials submitted as proof of infestation actually contained lice or nits. The same study found that among children attending schools with “no-nit” policies, 73% were identified as having lice while just 39% of the samples taken from these children actually supported the head lice diagnosis. These findings suggest the difficulty of treating head lice.
Head Lice: Identification and Management
Head lice feed on blood 2 to 6 times a day. Live infestations can be confirmed by combing dry hair with a dedicated fine tooth comb. Live lice can also be identified on the scalp using a 5X lighted magnifier and confirmed with a 10X magnified loupe. Treatments including wet combing (manual removal), homeopathic remedies, as well as OTC and prescription agents for the treatment of lice are available; however, many factors should be considered.
Wet combing with a fine-tooth comb and magnifier is performed every 3 to 4 days for at least 2 weeks but is considered ineffective when used alone. Homeopathic products such as shampoo may contain extracts of paw paw, thymol, and tea tree oil, which may cause allergic dermatitis. Some homeopathic shampoos may contain sodium chloride 10%, which can cause stinging upon application. The safety and efficacy of these homeopathic shampoos have not been sufficiently evaluated in controlled clinical trials, and their use in treating head lice is unproven. It is commonly believed that occlusive agents, such as petrolatum, olive oil, mayonnaise, or margarine, suffocate lice, and that their application will either kill the lice or slow them down sufficiently to make them easier to remove. However, no existing clinical evidence supports these beliefs. Diluted vinegar has been recommended to loosen the attachment of nits to hair shafts, but again, there is no evidence to support the effectiveness of this treatment. The folk remedy of applying kerosene or gasoline should never be employed due to the flammability hazard. These products, including the previously mentioned homeopathic and “natural” products, may cause local burning or irritation if applied topically. Pediculicides, agents used to treat head lice, may also contain neurotoxins as active ingredients; some resistance has been reported with the use of these products.
Clinical evidence of effectiveness exists for permethrin 1% formulations. However, in the early 1990s, a growing head lice resistance to permethrin was suspected in France and later confirmed in the United Kingdom, Israel, Australia, Argentina, and the United States (US). Due to this resistance, malathion—an effective and FDA-approved treatment—was reintroduced to the US market in 1999. Unfortunately, malathion resistance appears to be increasing; also, malathion is only indicated for children 6 years of age and older.
Benzyl Alcohol Lotion 5%
Ulesfia™ (benzyl alcohol lotion) is an FDA-approved prescription lotion indicated for the topical treatment of head lice infestation in patients 6 months of age and older. Ulesfia does not have ovicidal activity (which means it does not kill eggs). Based on laboratory studies, Ulesfia works by suffocating head lice, and its formulation is non-neurotoxic. Ulesfia also presents an alternative to agents to which head lice have developed resistance. Ulesfia lotion disables the breathing structure (spiracle) of the louse, holding it open and enabling the lotion to penetrate and fill the spiracle, resulting in suffocation.
Two controlled clinical studies were conducted in a total of 628 patients that were 6 months of age or older with active head lice infestations. To evaluate the efficacy of Ulesfia, the youngest subject of each household where infestations were present was randomly treated with either Ulesfia or the same lotion base but not containing benzyl alcohol (ie, a “vehicle” or non-medicated lotion). Other household members with infestations were enrolled in a second group and received the same treatment as the youngest patients, but were only observed to evaluate product safety.
In the first study, there were 125 patients that participated in the efficacy study; 63 patients used Ulesfia, and the remaining 62 were treated with the vehicle. The second study also had 125 patients; 64 were treated with Ulesfia and 61 used the vehicle. Each product (Ulesfia or the vehicle) was applied 2 times separated by 1 week.
Efficacy was assessed as the percent of patients who were free of live lice 14 days after the second application. Subjects with live lice present at any time after first treatment were considered treatment failures. Results showed that 76.2% and 75.0% of patients were lice-free after using Ulesfia, compared with 4.8% and 26.2% of patients who used the vehicle; data are from studies 1 and 2, respectively.
In July 2009, the FDA issued a consumer guide on the topic of the treatment of head lice that announced the approval of Ulesfia. The article points out that many OTC products are not indicated for children under 2 years of age, whereas Ulesfia is approved for use in children 6 months of age and older. Full text of the FDA health information article can be found on the FDA website at www.fda.gov/downloads/ForConsumers/ConsumerUpdates/UCM173526.pdf.
Important Safety Information for Ulesfia