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Pediculosis capitis

Adam O Goldstein, MD, MPH
Beth G Goldstein, MD
Section Editors
Robert P Dellavalle, MD, PhD, MSPH
Moise L Levy, MD
Ted Rosen, MD
Deputy Editor
Abena O Ofori, MD


Pediculosis capitis is a common condition caused by infestation of the hair and scalp by Pediculus humanus capitis (the head louse), one of three distinct varieties of lice specifically parasitic for humans (figure 1) [1]. The clinical manifestations, diagnosis, and treatment of pediculosis capitis will be reviewed here. Other forms of louse infestation, including pediculosis corporis and pediculosis pubis, are discussed separately. (See "Pediculosis corporis" and "Pediculosis pubis and pediculosis ciliaris".)


The head louse is an adaptable creature that is found worldwide, and infestations occur in individuals of all socioeconomic backgrounds [2]. Children are affected most commonly; with the exception of the common cold, pediculosis capitis affects a greater number of elementary school students in North America than all other communicable diseases combined. It has been estimated that in 1997 approximately one of every four elementary level students in the United States was infested [3,4].

Males appear to be less susceptible to lice infestations than females [5-7], and in the United States, black children are affected much less frequently than whites and others [8]. The reasons for these findings are uncertain. It is possible that the lower incidence in black children in the US may be related to the prevalence of lice in the US that are less capable of grasping the shape or width of certain types of hair [8]. Studies investigating the impact of long hair length on the risk of louse infestation have yielded conflicting results [5,6,9].


Although direct contact with the head of an infested person generally is considered the primary mode of transmission of pediculosis capitis [8,10], data are insufficient for definitive conclusions on the significance of specific routes of louse transmission. In particular, the degree to which inanimate objects contribute to the spread of pediculosis capitis is controversial [11,12]. While a study performed in an experimental setting suggested that use of hair dryers, combs, or towels could contribute to louse transmission [13], other studies investigating the prevalence of lice on fomites hats, bedding, and floors after exposure to an infested individual have not supported these routes as important modes of louse transmission [14-16]. Additional studies are necessary to clarify the role of inanimate objects in the risk for louse transmission.


The head louse is a gray-white, mobile insect 3 to 4 mm in length (picture 1). The female is a little longer than the male. Both sexes are equipped with mouth parts adapted to sucking blood and legs adapted to grasping hairs. The life span of the female is about one month, during which time she lays 7 to 10 eggs each day, cementing them firmly to the base of a host hair. The eggs, commonly called "nits," are oval capsules that hatch in eight days, releasing nymphs that require another eight days to mature (picture 2A-B). After hatching, egg cases become white and more visible. Adults feed voraciously both on the scalp and adjacent areas of the face and neck.


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Literature review current through: Sep 2015. | This topic last updated: May 20, 2015.
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  1. Ko CJ, Elston DM. Pediculosis. J Am Acad Dermatol 2004; 50:1.
  2. Roberts RJ. Clinical practice. Head lice. N Engl J Med 2002; 346:1645.
  3. Price JH, Burkhart CN, Burkhart CG, Islam R. School nurses' perceptions of and experiences with head lice. J Sch Health 1999; 69:153.
  4. A modern scourge: parents scratch their heads over lice. Consum Rep 1998; 63:62.
  5. Counahan M, Andrews R, Büttner P, et al. Head lice prevalence in primary schools in Victoria, Australia. J Paediatr Child Health 2004; 40:616.
  6. Suleman M, Fatima T. Epidemiology of head lice infestation in school children at Peshawar, Pakistan. J Trop Med Hyg 1988; 91:323.
  7. Downs AM, Stafford KA, Coles GC. Head lice: prevalence in schoolchildren and insecticide resistance. Parasitol Today 1999; 15:1.
  8. Head lice. Centers for Disease Control and Prevention. www.cdc.gov/lice/head/index.html. (Accessed on January 01, 2010).
  9. Willems S, Lapeere H, Haedens N, et al. The importance of socio-economic status and individual characteristics on the prevalence of head lice in schoolchildren. Eur J Dermatol 2005; 15:387.
  10. Frankowski BL, Bocchini JA Jr, Council on School Health and Committee on Infectious Diseases. Head lice. Pediatrics 2010; 126:392.
  11. Burkhart CN, Burkhart CG. Fomite transmission in head lice. J Am Acad Dermatol 2007; 56:1044.
  12. Canyon DV, Speare R. Indirect transmission of head lice via inanimate objects. Open Dermatology Journal 2010; 4:72.
  13. Takano-Lee M, Edman JD, Mullens BA, Clark JM. Transmission potential of the human head louse, Pediculus capitis (Anoplura: Pediculidae). Int J Dermatol 2005; 44:811.
  14. Speare R, Cahill C, Thomas G. Head lice on pillows, and strategies to make a small risk even less. Int J Dermatol 2003; 42:626.
  15. Speare R, Buettner PG. Hard data needed on head lice transmission. Int J Dermatol 2000; 39:877.
  16. Speare R, Thomas G, Cahill C. Head lice are not found on floors in primary school classrooms. Aust N Z J Public Health 2002; 26:208.
  17. Chunge RN, Scott FE, Underwood JE, Zavarella KJ. A pilot study to investigate transmission of headlice. Can J Public Health 1991; 82:207.
  18. Maunder JW. An update on headlice. Health Visit 1993; 66:317.
  19. Jahnke C, Bauer E, Hengge UR, Feldmeier H. Accuracy of diagnosis of pediculosis capitis: visual inspection vs wet combing. Arch Dermatol 2009; 145:309.
  20. Mumcuoglu KY, Friger M, Ioffe-Uspensky I, et al. Louse comb versus direct visual examination for the diagnosis of head louse infestations. Pediatr Dermatol 2001; 18:9.
  21. Williams LK, Reichert A, MacKenzie WR, et al. Lice, nits, and school policy. Pediatrics 2001; 107:1011.
  22. Dodd CS. Interventions for treating headlice. Cochrane Database Syst Rev 2001; :CD001165.
  23. Keipert JA. Hair casts. Review and suggestion regarding nomenclature. Arch Dermatol 1986; 122:927.
  24. França K, Villa RT, Silva IR, et al. Hair casts or pseudonits. Int J Trichology 2011; 3:121.
  25. Bonifaz A, Gómez-Daza F, Paredes V, Ponce RM. Tinea versicolor, tinea nigra, white piedra, and black piedra. Clin Dermatol 2010; 28:140.
  26. Burkhart CG, Burkhart CN, Burkhart KM. An assessment of topical and oral prescription and over-the-counter treatments for head lice. J Am Acad Dermatol 1998; 38:979.
  27. Devore CD, Schutze GE, Council on School Health and Committee on Infectious Diseases, American Academy of Pediatrics. Head lice. Pediatrics 2015; 135:e1355.
  28. Lebwohl M, Clark L, Levitt J. Therapy for head lice based on life cycle, resistance, and safety considerations. Pediatrics 2007; 119:965.
  29. Frankowski BL, Weiner LB, Committee on School Health the Committee on Infectious Diseases. American Academy of Pediatrics. Head lice. Pediatrics 2002; 110:638.
  30. Meinking TL, Clineschmidt CM, Chen C, et al. An observer-blinded study of 1% permethrin creme rinse with and without adjunctive combing in patients with head lice. J Pediatr 2002; 141:665.
  31. Meinking TL, Serrano L, Hard B, et al. Comparative in vitro pediculicidal efficacy of treatments in a resistant head lice population in the United States. Arch Dermatol 2002; 138:220.
  32. Malathion for treatment of head lice. Med Lett Drugs Ther 1999; 41:73.
  33. Frankowski BL. American Academy of Pediatrics guidelines for the prevention and treatment of head lice infestation. Am J Manag Care 2004; 10:S269.
  34. Takano-Lee M, Edman JD, Mullens BA, Clark JM. Home remedies to control head lice: assessment of home remedies to control the human head louse, Pediculus humanus capitis (Anoplura: Pediculidae). J Pediatr Nurs 2004; 19:393.
  35. Meinking TL, Vicaria M, Eyerdam DH, et al. Efficacy of a reduced application time of Ovide lotion (0.5% malathion) compared to Nix creme rinse (1% permethrin) for the treatment of head lice. Pediatr Dermatol 2004; 21:670.
  36. US FDA drug label. www.accessdata.fda.gov/drugsatfda_docs/label/2009/022129lbl.pdf. (Accessed on March 25, 2010).
  37. Meinking TL, Villar ME, Vicaria M, et al. The clinical trials supporting benzyl alcohol lotion 5% (Ulesfia): a safe and effective topical treatment for head lice (pediculosis humanus capitis). Pediatr Dermatol 2010; 27:19.
  38. McCormack PL. Spinosad: in pediculosis capitis. Am J Clin Dermatol 2011; 12:349.
  39. Stough D, Shellabarger S, Quiring J, Gabrielsen AA Jr. Efficacy and safety of spinosad and permethrin creme rinses for pediculosis capitis (head lice). Pediatrics 2009; 124:e389.
  40. Ivermectin (Sklice) topical lotion for head lice. Med Lett Drugs Ther 2012; 54:61.
  41. Pariser DM, Meinking TL, Bell M, Ryan WG. Topical 0.5% ivermectin lotion for treatment of head lice. N Engl J Med 2012; 367:1687.
  42. US Food and Drug Administration public health advisory on lindane. www.fda.gov/Drugs/DrugSafety/PostmarketDrugSafetyInformationforPatientsandProviders/ucm110845.htm (Accessed on October 09, 2009).
  43. Humphreys EH, Janssen S, Heil A, et al. Outcomes of the California ban on pharmaceutical lindane: clinical and ecologic impacts. Environ Health Perspect 2008; 116:297.
  44. Burkhart CG. Relationship of treatment-resistant head lice to the safety and efficacy of pediculicides. Mayo Clin Proc 2004; 79:661.
  45. Yoon KS, Gao JR, Lee SH, et al. Permethrin-resistant human head lice, Pediculus capitis, and their treatment. Arch Dermatol 2003; 139:994.
  46. Hunter JA, Barker SC. Susceptibility of head lice (Pediculus humanus capitis) to pediculicides in Australia. Parasitol Res 2003; 90:476.
  47. Kasai S, Ishii N, Natsuaki M, et al. Prevalence of kdr-like mutations associated with pyrethroid resistance in human head louse populations in Japan. J Med Entomol 2009; 46:77.
  48. Durand R, Millard B, Bouges-Michel C, et al. Detection of pyrethroid resistance gene in head lice in schoolchildren from Bobigny, France. J Med Entomol 2007; 44:796.
  49. Downs AM, Stafford KA, Hunt LP, et al. Widespread insecticide resistance in head lice to the over-the-counter pediculocides in England, and the emergence of carbaryl resistance. Br J Dermatol 2002; 146:88.
  50. Pollack RJ, Kiszewski A, Armstrong P, et al. Differential permethrin susceptibility of head lice sampled in the United States and Borneo. Arch Pediatr Adolesc Med 1999; 153:969.
  51. Downs AM, Narayan S, Stafford KA, Coles GC. Effectiveness of ovide against malathion-resistant head lice. Arch Dermatol 2005; 141:1318.
  52. Soderlund DM. Pyrethroids, knockdown resistance and sodium channels. Pest Manag Sci 2008; 64:610.
  53. Bialek R, Zelck UE, Fölster-Holst R. Permethrin treatment of head lice with knockdown resistance-like gene. N Engl J Med 2011; 364:386.
  54. Meinking TL, Vicaria M, Eyerdam DH, et al. A randomized, investigator-blinded, time-ranging study of the comparative efficacy of 0.5% malathion gel versus Ovide Lotion (0.5% malathion) or Nix Crème Rinse (1% permethrin) used as labeled, for the treatment of head lice. Pediatr Dermatol 2007; 24:405.
  55. Spinosad (Natroba) topical suspension for head lice. Med Lett Drugs Ther 2011; 53:50.
  56. Lapeere H, Brochez L, Verhaeghe E, et al. Efficacy of products to remove eggs of Pediculus humanus capitis (Phthiraptera: Pediculidae) from the human hair. J Med Entomol 2014; 51:400.
  57. Roberts RJ, Casey D, Morgan DA, Petrovic M. Comparison of wet combing with malathion for treatment of head lice in the UK: a pragmatic randomised controlled trial. Lancet 2000; 356:540.
  58. Hill N, Moor G, Cameron MM, et al. Single blind, randomised, comparative study of the Bug Buster kit and over the counter pediculicide treatments against head lice in the United Kingdom. BMJ 2005; 331:384.
  59. Dawes M. Combing and combating head lice. BMJ 2005; 331:362.
  60. Burkhart CN, Burkhart CG. Another look at ivermectin in the treatment of scabies and head lice. Int J Dermatol 1999; 38:235.
  61. Drugs for parasitic infections. Med Lett Drugs Ther 1995; 37:99.
  62. Chosidow O, Giraudeau B, Cottrell J, et al. Oral ivermectin versus malathion lotion for difficult-to-treat head lice. N Engl J Med 2010; 362:896.
  63. Ameen M, Arenas R, Villanueva-Reyes J, et al. Oral ivermectin for treatment of pediculosis capitis. Pediatr Infect Dis J 2010; 29:991.
  64. Currie MJ, Reynolds GJ, Glasgow NJ, Bowden FJ. A pilot study of the use of oral ivermectin to treat head lice in primary school students in Australia. Pediatr Dermatol 2010; 27:595.
  65. Pilger D, Heukelbach J, Khakban A, et al. Household-wide ivermectin treatment for head lice in an impoverished community: randomized observer-blinded controlled trial. Bull World Health Organ 2010; 88:90.
  66. Glaziou P, Nyguyen LN, Moulia-Pelat JP, et al. Efficacy of ivermectin for the treatment of head lice (Pediculosis capitis). Trop Med Parasitol 1994; 45:253.
  67. Burkhart CG, Burkhart CN. Head lice therapies revisited. Dermatol Online J 2006; 12:3.
  68. Nofal A. Oral ivermectin for head lice: a comparison with 0.5 % topical malathion lotion. J Dtsch Dermatol Ges 2010; 8:985.
  69. Twum-Danso NA. Serious adverse events following treatment with ivermectin for onchocerciasis control: a review of reported cases. Filaria J 2003; 2 Suppl 1:S3.
  70. Gardon J, Gardon-Wendel N, Kamgno J, et al. Serious reactions after mass treatment of onchocerciasis with ivermectin in an area endemic for Loa loa infection. Lancet 1997; 350:18.
  71. Hipolito RB, Mallorca FG, Zuniga-Macaraig ZO, et al. Head lice infestation: single drug versus combination therapy with one percent permethrin and trimethoprim/sulfamethoxazole. Pediatrics 2001; 107:E30.
  72. Pearlman DL. A simple treatment for head lice: dry-on, suffocation-based pediculicide. Pediatrics 2004; 114:e275.
  73. Pearlman D. Cetaphil cleanser (Nuvo lotion) cures head lice. Pediatrics 2005; 116:1612.
  74. Roberts RJ, Burgess IF. New head-lice treatments: hope or hype? Lancet 2005; 365:8.
  75. Burgess IF, Brown CM, Lee PN. Treatment of head louse infestation with 4% dimeticone lotion: randomised controlled equivalence trial. BMJ 2005; 330:1423.
  76. Burgess IF, Brunton ER, French R, Burgess NA. Prevention of head louse infestation: a randomised, double-blind, cross-over study of a novel concept product, 1% 1,2-octanediol spray versus placebo. BMJ Open 2014; 4:e004634.
  77. Burgess IF, Lee PN, Kay K, et al. 1,2-Octanediol, a novel surfactant, for treating head louse infestation: identification of activity, formulation, and randomised, controlled trials. PLoS One 2012; 7:e35419.
  78. Lwegaba A. Shaving can be safer head lice treatment than insecticides. BMJ 2005; 330:1510.
  79. Resnik KS. A non-chemical therapeutic modality for head lice. J Am Acad Dermatol 2005; 52:374.
  80. Goates BM, Atkin JS, Wilding KG, et al. An effective nonchemical treatment for head lice: a lot of hot air. Pediatrics 2006; 118:1962.