Treatment

Treatment is recommended in the presence of a living louse which confirms the active disease. All family members should be investigated for active lice infestation and those infested must be treated simultaneously (1).

Three treatment methods are available for head lice infestations:

• 1. Insecticides (2)
  • there is evidence of widespread malathion and pyrethroid resistance, as well as the emergence of carbaryl resistance in the UK, hence choice of treatment will depend on patterns of regional resistance. Please refer to local guidelines

Physical insecticides kill the lice by physically coating their surfaces and suffocating them, so resistance is unlikely to develop.

These include;

• dimeticone 4% gel, lotion, or spray
• dimeticone 92% spray
• dimeticone >95% lotion
• isopropyl myristate and cyclomethicone solution
• isopropyl myristrate and isopropyl alcohol aerosol.

Chemical or traditional insecticides poison the lice by chemical mean and the only chemical insecticide that is currently recommended in the UK is Malathion 0.5% aqueous liquid, but resistance has been reported.

This should be applied twice, with seven days between applications It is applied to the hair from the roots to the tips, left on the hair and scalp for 12 hours or overnight and then washed out using shampoo.

• in cases of treatment failure with one group of insecticide, switching to a different class is recommended

• 2. Wet combing
  • requires a minimum of four sessions spaced over two weeks and should be continued until absence of full grown lice is seen for three consecutive sessions (1)
  • wet-combing with a fine-toothed comb has been proposed as an option as a first-line treatment in response to the increase in pediculicide resistance

The Bug Buster® kit is the only head lice removal (and detection) method that has been evaluated in controlled trials. It is available on the NHS.

In a pregnant or lactating woman wet combing or dimeticone is advised.

• 3. Dimeticone

Dimeticones are generally considered a first-line treatment but permethrin 1%, as well as pyrethrins and organophosphate compounds (with or without piperonyl butoxide), may also be recommended depending on local guidelines.

Dimeticone lotion applied to dry hair and scalp should be kept on for 8 hours or overnight and repeated after 7days (2)

In areas with known resistance to over-the-counter pediculicides, a prescription-only drug is recommended. Ivermectin topical lotion, spinosad, or malathion are suitable options.

These products should only be used in patients over 6 months of age (except malathion, which is recommended in children over the age of 6 only) (3)

Response to treatment should be evaluated 2-3 days after completing a course of treatment by detection combing method. The test can be repeated 8-10 days after treatment to detect any louse eggs that have survived (1).

Other agents:

Essential oils and other plant-derived compounds have been widely used in traditional medicine for the eradication of head lice, but due to the variability of their constitution in commercial products, the effects may not be reproducible and at the present time there is insufficient evidence to recommend their use (4)

The summary of product characteristics must be consulted before prescribing any of the drugs mentioned.

Reference:

1. Public Health Medicine Environmental Group. Head lice: evidence-based guidelines based on the Stafford Report - 2012 update [internet publication].

2. Feldmeier H. Treatment of pediculosis capitis: a critical appraisal of the current literature. Am J Clin Dermatol. 2014 Oct;15(5):401-12.

3. American Academy of Pediatrics, Nolt D, Moore S, et al. Head Lice. Pediatrics. 2022 Oct 1;150(4)

4. Takano-Lee M, Edman JD, Mullens BA, et al. Home remedies to control head lice: assessment of home remedies to control the human head louse, Pediculus humanus capitis. J Ped Nursing. 2004 Dec;19(6):393-8.