Last reviewed: 16 Apr 2021
Last updated: 03 May 2018



History and exam

Key diagnostic factors

  • scalp pruritus
  • live nymphal or adult louse
  • eggs visible on hair shaft within 1 cm of scalp

Other diagnostic factors

  • small red papules under hairline at nape of neck
  • lymphadenopathy
  • erythema with honey-colored crust on scalp

Risk factors

  • 3 to 12 years of age
  • female gender
  • ethnicity other than black
  • close contact with infested individual
  • overcrowding or close living conditions
  • low socioeconomic status
  • poor hygiene
  • contact with contaminated clothes, hair care items, bedding

Diagnostic investigations

Treatment algorithm


Professor of Dermatology

Faculty of Medicine

University of Algiers



AS declares that she has no competing interests.

Professor Aicha Salhi would like to gratefully acknowledge Professor Hermann Feldmeier and Professor Barbara L. Frankowski, previous contributors to this topic. HF has received consultant and lecture fees from Pohl-Boskamp GmbH, and Co KG, Hohenlockstedt, Germany, and Almirall Hermal GmbH, Reinbek, Germany; both companies produce various anti-head louse compounds. He is also an author of several references cited in this topic. BLF is an author of a reference cited in this topic.

Peer reviewersVIEW ALL

Research Associate

Laboratory of Public Health Entomology

Department of Immunology and Infectious Diseases

Harvard School of Public Health




RJP has received a research donation by Taro Pharmaceuticals (manufacturer of Ovide) and has been compensated as an independent consultant for scientific review services by Topaz Pharmaceuticals, Hatchtech, and ParaPro, each developing products for the US market. RJP holds no financial interest in any of these companies or their products. RJP is an author of several references cited in this monograph.



Medical Entomology Centre

University of Cambridge




IFB has been a consultant to various manufacturers of pharmaceutical products, alternative therapies, and combs for treating louse infections. IFB is an author of several references cited in this monograph.


Department of Parasitology

Hebrew University-Hadassah Medical School




KYM is an author of several references cited in this monograph.

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