Head Lice: Diagnosis and Therapy

Gabriel J. Martinez-Diaz, MD; Anthony J. Mancini, MD

Dermatology Nursing

Patient Education

Since head lice are transmitted primarily person-to-person, avoidance of head-to-head contact is important. In addition, combs, brushes, hats, and other headgear can also transmit lice, so sharing of these items should be strongly discouraged, especially in places where close contact is likely, such as schools, camps, and daycare centers. Hair grooming items used by an infested person, if not discarded, should be de-infested by soaking them in hot water (of at least 130° F) for 5–10 minutes. Washable clothing and linens should be laundered with a minimum water temperature of 50° C or with a dry cycle for at least 40 minutes (West, 2004). Items that are not washable, such as stuffed animals, should be sealed in plastic bags for 2 weeks or dry cleaned. Upholstered furniture can be vacuumed. Fumigation of the household is not necessary, and these products can be toxic if inhaled or absorbed through the skin (AAP, 2009; CDC, 2008).

Children identified as having head lice should be referred for treatment and excluded from school only until the recommended treatment has been completed. According to the Committee on Infectious Diseases of the American Academy of Pediatrics, "no-nit" policies, whereby schools and child-care institutions require children be free of nits before they return, have not been effective in controlling pediculosis capitis transmission and are not recommended (AAP, 2009) Additionally, children should not be excluded or sent home early from school because of head lice. Instead, parents should be notified of the infestation and requested to have their child treated before returning to school on the day after treatment (AAP, 2009). School contacts should not be treated prophylactically, but should be notified and evaluated for infestation. Caregivers who have prolonged skin-to-skin contact with students infested with lice, though, may benefit from prophylactic treatment (CDC, 2008).

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Cite this: Head Lice: Diagnosis and Therapy - Medscape - Jul 01, 2010.

Table 1. Differential Diagnosis of Nits
Diagnosis	Comment
Dandruff	Scales throughout the scalp; may attach to hairs; easily removed
Hair casts	Keratin protein that encircles the hair shaft; may be multiple; easily removed
Piedra	Fungal hair infection; firm nodules attached to hair shafts; usually white or black in color
Hair products	For example, hair spray, mousse, gel
Psoriasis	Thickened scaly plaques usually present in scalp

Table 2. Treatments for Head Lice
Type	Treatment (Brands)	Regimen	Comment
OTC
	Permethrin 1% cream rinse (Nix)	Apply to damp hair after shampooing, leave on 10 minutes, rinse. Repeat in 7–10 days.	May cause mild irritation.
	Pyrethrins 0.33% shampoo, lotion (Rid, Pronto, A-200)	Apply to dry hair, leave on 10 minutes, rinse. Repeat in 7–10 days.	May cause mild irritation.
Rx
	Lindane 1% shampoo, lotion (None; formerly Kwell)	Apply to dry hair, leave on 4 minutes, rinse.	Possible central nervous system toxicity, seizure risk (although generally only seen with incorrect usage).
	Benzyl alcohol 5% lotion (Ulesfia)	Apply to dry hair, leave on 10 minutes, rinse. Repeat in 7 days.	Kills head lice by asphyxiation; contains no neurotoxic pesticide.
	Malathion 5% lotion (Ovide)	Apply to dry hair, leave on 8–12 hours, rinse. Repeat in 7–10 days.	Approved >6 years; vehicle is flammable.
	Trimethoprim-sulfamethoxazole (Bactrim)	8–10 mg/kg/day divided BID for 10 days	Occasionally used off-label (not FDA-approved for lice); kills symbiotic bacteria in gut of louse; risk of severe allergic drug reactions.
	Ivermectin 3 mg/6 mg tablets (Stromectol)	Single oral dose of 200 mcg/kg. Repeat in 7–10 days.	Occasionally used off-label for resistant cases (FDA-approved for strongyloidiasis, onchocerciasis); possible side effects include headache, dizziness, nausea, vomiting.
Alternative	Occlusive agents (petroleum jelly, olive oil, mayonnaise, others)	Applied and usually left on overnight, then rinsed out.	No conclusive evidence-based data on the effectiveness or safety of these treatments.

Notes: OTC = over-the-counter; Rx = prescription; BID = twice daily.

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Head Lice: Diagnosis and Therapy

Patient Education

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