Head Lice: Diagnosis and Therapy

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

Dermatology Nursing

Abstract and Introduction

Abstract

Children worldwide are commonly infected with head lice, or pediculosis capitis. The epidemiology, etiology, clinical manifestations, diagnosis, and preventive and treatment modalities for managing head lice in children are reviewed.

Introduction

Head lice, also known as pediculosis capitis, has a worldwide prevalence of up to 60% (Falagas, Matthaiou, Rafailidis, Panos, & Pappas, 2008). It is caused by the head louse, Pediculosishumanus var. capitis, which may infest children of any age, but most frequently those between 3 and 12 years of age in the United States (Falagas et al., 2008). African Americans are less commonly infested, which may be due to the twisted nature of the hair shaft, the use of hair pomades, or the diameter and shape of their hair shafts, which may make grasping of the shaft more difficult (Diamantis, Morrell, & Burkhart, 2009; Frankowski & Weiner, 2002; Ko & Elston, 2004; Rubeiz & Kibbi, 2009). Although traditionally believed to be associated with low socioeconomic status, poor hygiene, longer hair, or frequency of shampooing or brushing, head lice infestation is not dependent on these variables. The human head louse does not transmit disease, but can be socially stigmatizing and places a significant burden on patients, parents, and society. The annual direct and indirect costs of head lice infestations in the United States are estimated to be in the hundreds of millions of dollars (Clore & Longyear, 1990; Frankowski & Weiner, 2002; West, 2004).

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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

Abstract and Introduction

Abstract

Introduction

Tables

Tables

References

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Authors and Disclosures

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