← Back to guidelines
Dermatology18 papers

Infestation by biting lice

Last edited: 4/15/2026

Overview

Head lice infestation, caused by Pediculus humanus var. capitis, involves biting and feeding on human blood, leading to pruritus and potential secondary infections. Effective management requires thorough removal of lice and nits.

Diagnosis

  • Visual inspection of hair and scalp for live lice and nits.
  • Nits typically found close to the scalp, distinguished from hair debris by their oval shape and darker color.
  • No specific laboratory tests required; clinical examination is definitive 1.
  • Management

  • First-line treatment: Use of pediculicide shampoos or lotions, such as permethrin 1% creme rinse 2.
  • Combing: Essential post-treatment to remove dead lice and nits; metal combs like the Lice Meister are more effective than plastic combs 1.
  • Re-treatment: Recommended after 7-10 days if live lice are still present 2.
  • Special Populations

  • Pediatrics: Permethrin 1% creme rinse is safe and effective in children, with no serious adverse events reported in postmarketing surveillance 2.
  • No specific guidance provided for elderly or pregnant populations in the given abstracts.
  • Key Recommendations

  • Utilize metal combs, such as the Lice Meister, for combing to enhance removal of nits and lice post-treatment (Evidence: Moderate) 1.
  • Employ permethrin 1% creme rinse as a first-line treatment for head lice infestations, with re-treatment considered if necessary after 7-10 days (Evidence: Strong) 2.
  • Conduct thorough combing sessions post-treatment to ensure removal of dead lice and nits (Evidence: Expert opinion) 1.
  • References

    1 Speare R, Canyon DV, Cahill C, Thomas G. Comparative efficacy of two nit combs in removing head lice (Pediculus humanus var. capitis) and their eggs. International journal of dermatology 2007. link 2 Andrews EB, Joseph MC, Magenheim MJ, Tilson HH, Doi PA, Schultz MW. Postmarketing surveillance study of permethrin creme rinse. American journal of public health 1992. link

    Original source

    1. [1]
      Comparative efficacy of two nit combs in removing head lice (Pediculus humanus var. capitis) and their eggs.Speare R, Canyon DV, Cahill C, Thomas G International journal of dermatology (2007)
    2. [2]
      Postmarketing surveillance study of permethrin creme rinse.Andrews EB, Joseph MC, Magenheim MJ, Tilson HH, Doi PA, Schultz MW American journal of public health (1992)

    HemoChat

    by SPINAI

    Evidence-based clinical decision support powered by SNOMED-CT, Neo4j GraphRAG, and NASS/AO/NICE guidelines.

    ⚕ For clinical reference only. Not a substitute for professional judgment.

    © 2026 HemoChat. All rights reserved.
    Research·Pricing·Privacy & Terms·Refund·SNOMED-CT · NASS · AO Spine · NICE · GraphRAG