Simultaneous treatment of all affected household contacts

• The recommendation to treat all infested household contacts simultaneously is based on expert opinion [Ibarra et al, 2007; PHMEG, 2008]. Reinfestation from close contacts is a common cause of treatment failure.

Advice on hygiene measures

• There is no need to wash clothing or bedding that has been in contact with lice, because head lice that fall off the head (for example onto hats or pillows) are likely to die soon [Nash, 2003; DH, 2005; HPA, 2008].

Choice of treatment

• There is limited evidence to support the effectiveness of each treatment option recommended. No option is clearly superior or inferior to the others in terms of effectiveness and there are advantages and disadvantages for each method, and no method can guarantee success. The choice of a particular treatment strategy will depend on individual or parent preference, and success or failure with previous treatments.
• Products with a short contact time have previously not been recommended because, for traditional insecticides, a short application time is thought to be insufficient to allow the product to exert its effect, which in turn is thought to contribute to insecticide resistance. Although both isopropyl myristate (Full Marks Solution^®) and coconut, anise, and ylang ylang spray (Lyclear SprayAway^®) have short contact times, their physical mode of action mean that a longer contact time is unlikely to be needed, provided the product is applied correctly.

Number of treatment sessions

• The recommendation for two applications of traditional or physical insecticide, 7 days apart, is based on expert opinion [PHMEG, 2008]. The second application of traditional or physical insecticide is intended to kill nymphs emerging from eggs that survived the first application. One formulation of malathion aqueous liquid (Derbac-M^®) is now licensed for use as two treatments, 7 days apart.
• The recommendation to continue wet combing until no full-grown lice have been seen at three consecutive sessions is to ensure that that reinfestation is recognized, and that nymphs are removed shortly after hatching (i.e. before they reach maturity and become able to reproduce) [Ibarra, 1998].

Treatments that are not recommended

• Permethrin is not recommended because there are concerns that a 10-minute contact time is not long enough for the product to be effective, and because there is evidence of resistance to permethrin in the UK. A recent randomized controlled trial conducted in the UK reported a cure rate of only 19% with permethrin 1% cream rinse [Burgess et al, 2008].
• Phenothrin and carbaryl are no longer available in the UK.
• Insecticide shampoos are not recommended because there are concerns that they become too dilute when used to be effective [Burgess, 2001; PHMEG, 2008; BNF 57, 2009].
• Hedrin^® solution, gel, or spray (dimeticone 4%). Hedrin^® Once liquid and gel are registered as Class 1 medical devices in the UK. They are not listed in the Drug Tariff and so cannot be prescribed on FP10 [Prescription Pricing Division, 2010]. Hedrin ^® solution and spray (licensed medicinal products) are also not included. CKS found no published randomized controlled trials studying the efficacy of these formulations of dimeticone in eradicating head lice.
• NYDA^® (dimeticone 92% spray) is registered as a Class 1 medical device in the UK. It is not listed in the Drug Tariff and so it cannot be prescribed on FP10 [Prescription Pricing Division, 2009]. CKS found one randomized controlled trial studying the efficacy of an identical strength formulation in eradicating head lice.
• Nitty Gritty NitFree comb^®, Nitcomb–S1^®, Nitcomb–M2^® (all metal combs) are all listed in the Drug Tariff and can, therefore be prescribed on FP10. However, CKS found no randomized controlled trials evaluating their efficacy in removing head lice. In addition, CKS expert reviewers recommend that metal nit combs such as these are not suitable for use as louse detection combs. Combs primarily for nit removal must have teeth less than the width of a nit apart to exert traction. This is too close for louse detection because lice trapped between the teeth remain unseen and can be combed back onto the head unharmed [Ibarra, 2008].
• Lice Attack^® (a coconut oil shampoo) is registered as a Class 1 medical device in the UK. It is not listed in the Drug Tariff and so it cannot be prescribed on FP10 [Prescription Pricing Division, 2009]. CKS found no published randomized controlled trials studying its efficacy in eradicating head lice.
• Nitlotion^® (contains coconut oil) is registered as a Class 1 medical device in the UK and can be prescribed on FP10 [Prescription Pricing Division, 2009]. However, CKS found no published randomized controlled trials studying its efficacy in eradication of head lice.
• Dove^® hair conditioner is not recommended. There is an anecdotal report that Dove^® hair conditioners have been used to treat head lice [Eames, 2004]. These hair conditioners contain a low concentration of dimethiconol, a silicone polymer. However, CKS found no randomized trials supporting the use of this or other hair conditioners for the treatment of head lice.
• Electric combs are not recommended. Expert consensus is that they should not be used because they are expensive, they can pose a safety risk if used incorrectly, and there is a lack of evidence for their efficacy [PHMEG, 2008].
• Essential oil-based treatments and herbal remedies are not recommended unless their safety and efficacy has been evaluated in randomized controlled trials.
• Essential oil-based treatments and herbal remedies should not be assumed to be safe because they are 'natural'.
• There is some evidence from in vitro studies that some essential oils (such as tea tree oil, eucalyptus oil, lavender oil, peppermint oil, neem oil) have some activity against head lice [Gonzalez Audino et al, 2007]. However, most have not been evaluated in randomized controlled trials, and safety data are sparse.
• Products containing different percentages of the essential oil and different excipients cannot be assumed to have similar efficacy.
• Lyclear SprayAway^® (prescribable in the UK), which contains coconut and anise oil, was found to be effective in a single randomized controlled trial.
• One specific formulation of eucalyptus 11% solution marketed in Australia has been shown in a randomized clinical trial to be effective against head lice, although there are several methodological problems with this study that could have led to bias [Greive et al, 2007].
• Many products marketed as wet combing aids contain essential oils; but there are no randomized controlled trials that assess their efficacy or safety.
• Vinegar, isopropyl alcohol, olive oil, mayonnaise, melted butter, and petroleum jelly have been found to be ineffective in a laboratory study [Takano-Lee et al, 2004].