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Pediculicides are substances used to treat lice (Pediculus humanus capitis).[1]

Chemical treatments[edit]

Today, insecticides used for the treatment of head lice include organochlorines (lindane), organophosphates (malathion), carbamates (carbaryl), pyrethrins (pyrethrum), and pyrethroids (permethrin, phenothrin, bio-allethrin).

Laboratory and clinical studies found that many of the pediculicides in the market are either not fully effective or are ineffective when they are used according to the instructions.[2][3][4][5]

Pediculicides may rapidly lose their efficacy because of the development of resistance. Resistance of head lice to insecticides such as lindane, malathion, phenothrin and permethrin has been reported.[6][7][8]

Ivermectin (which can be given orally) has been shown to reduce levels of louse infestation.[9][10][11] Originally approved for onchocerciasis and strongyloidiasis,[12][13] Ivermectin is now approved by the FDA for pediculosis.[14]

Natural products[edit]

Clinical studies of natural products are very limited, and most have methodological problems such as lack of a comparison group.[4][15]

Enzyme-based products[edit]

Certain proteases can have insecticidal effects. This process works through using naturally occurring enzymes similar to those within the insects themselves. These proteolytic enzymes cause the insect to hatch and molt prematurely, destroying the creature's exoskeleton. These enzymes are similar to those found in meat tenderizers and digestive aids. The benefits of this type of treatment is that the lice do not develop resistance and these products are less toxic.

Silicone-based lotions[edit]

Dimethicone is a silicone oil, which coats and smothers the lice causing their death either by suffocation or dehydration. Most dimethicone lotions do not kill nits because the nits have only one breathing orifice, the operculum, so the dimethicone has less access there.

Accelerated Nano X-ray tomography of headlice treated with Silcap(4% dimethicone/96% mineral oil) ([1]). After 15 min the lice and nits are suffocated and dry out. Courtesy of Oystershell NV & University of Ghent

Therefore, most treatments should be repeated after 7–10 days to kill any lice that hatch from the eggs or to treat reinfection by family members or classmates .[16] Combination lotions and foams exist (Silcap,[17] manufactured by Oystershell NV) that have an immediate effect on nits (15 min, 96% mortality) by combining the rather viscous dimethicone with penetrating excipients that increase the delivery through the abdominal spiracles of adults and the operculum of the nits.[18] However, "Silcap is not yet available in the US. Import and distribution is still waiting for final FDA approval."[19]


The use of kerosene or gasoline for prevention or treatment of lice is dangerous due to the inherent fire hazard.[20][21] Since 1989, there have been at least nine cases of children being severely burned during such attempts. These cases apparently occurred because, contrary to popular belief, it is the fumes of the gasoline, rather than the liquid itself, that are flammable. These fumes can ignite due to the presence of even a small spark or open flame - such as those caused by electrical appliances, cigarette lighters, or pilot lights in stoves and water heaters. The use of gasoline to treat lice also carries a high risk of dermatitis (i.e. irritation of the scalp).[22]

Before gasoline (Petrol) was used as fuel, it was sold in small bottles as a treatment against lice and their eggs.[citation needed] At that time, the word Petrol was a trade name.[23]


  1. ^
  2. ^ Roberts, RJ; Casey D; Morgan DA; Petrovic M (12 August 2000). "Comparison of Wet Combing With Malathion for Treatment of Head Lice in the UK: A Pragmatic Randomised Controlled Trial" (abstract). The Lancet. Amsterdam: Elsevier. 356 (9229): 540–544. doi:10.1016/S0140-6736(00)02578-2. Retrieved 2008-01-03.
  3. ^ Mumcuoglu, KY; Miller, J. (1991). "The Efficacy of Pediculicides in Israel". Israel Journal of Medical Sciences. Jerusalem: Weizmann Science Press. 27 (10): 562–565.
  4. ^ a b Vander Stichele, Robert H; Dezeure Els M; Bogaert Marc G. (2 September 1999). "Systematic Review of Clinical Efficacy of Topical Treatments for Head Lice". British Medical Journal. London: BMJ Publishing Group Ltd. 311 (7005): 604–608. PMC 2550649. PMID 7545045. Retrieved 2008-01-03.
  5. ^ Meinking, Terri L.; Entzel, Pamela; Villar, Maria Elena; Vicaria, Maureen; Lemard, Glendene A; Porcelain, Sherri L. (March 2001). "Comparative Efficacy of Treatments for Pediculosis Capitis Infestations". Archives of Dermatology. Chicago: American Medical Association. 137 (3): 287–292. PMID 11255326. Retrieved 2008-01-03.
  6. ^ Pollack RJ, Kiszewski A, Armstrong P, Hahn C, Wolfe N, Rahman HA, Laserson K, Telford SR, Spielman A (September 1999). "Differential Permethrin Susceptibility of Head Lice Sampled in the United States and Borneo" (PDF). Archives of Pediatrics & Adolescent Medicine. Chicago: American Medical Association. 153 (9): 969–973. PMID 10482215. Retrieved 2008-01-03.[permanent dead link]
  7. ^ Burkhart, Craig G. (May 2004). "Relationship of Treatment-Resistant Head Lice to the Safety and Efficacy of Pediculicides" (PDF). Mayo Clinic Proceedings. Rochester, Minnesota: Mayo Clinic. 79 (5): 661–666. doi:10.4065/79.5.661. PMID 15132409. Retrieved 2008-01-03.[dead link]
  8. ^ Yoon, Kyong Sup; Gao, Jian-Rong; Lee, Si Hyeock; Clark, J. Marshall; Brown, Leon; Taplin, David (August 2003). "Permethrin-Resistant Human Head Lice, Pediculus capitis, and Their Treatment". Archives of Dermatology. Chicago: American Medical Association. 139 (8): 994–1000. doi:10.1001/archderm.139.8.994. PMID 12925385. Retrieved 2008-01-03.
  9. ^ Chosidow O, Giraudeau B, Cottrell J, et al. (March 2010). "Oral ivermectin versus malathion lotion for difficult-to-treat head lice". N. Engl. J. Med. 362 (10): 896–905. doi:10.1056/NEJMoa0905471. PMID 20220184. Archived from the original on 2013-01-13.
  10. ^ Munirathinam A, Sunish IP, Rajendran R, Tyagi BK (November 2009). "Impact of ivermectin drug combinations on Pediculus humanus capitis infestation in primary schoolchildren of south Indian rural villages". Int. J. Dermatol. 48 (11): 1201–5. doi:10.1111/j.1365-4632.2008.04059.x. PMID 20064176.
  11. ^ Foucault C, Ranque S, Badiaga S, Rovery C, Raoult D, Brouqui P (February 2006). "Oral ivermectin in the treatment of body lice". J. Infect. Dis. 193 (3): 474–6. doi:10.1086/499279. PMID 16388498.
  12. ^ Amy J. McMichael; Maria K. Hordinsky (2008). Hair and Scalp Diseases: Medical, Surgical, and Cosmetic Treatments. Informa Health Care. pp. 289–. ISBN 978-1-57444-822-1. Retrieved 27 April 2010.
  13. ^ "Pediculosis: Treatment & Medication - eMedicine Emergency Medicine". Retrieved 2010-04-26.
  14. ^
  15. ^ Mumcuoglu, Kosta; Miller, Jacqueline; Zamir, Chen; Zentner, Gary; Helbin, Valery; Ingber, Arieh (October 2002). "The In Vivo Pediculicidal Efficacy of a Natural Remedy". Israel Medical Association Journal. Ramat Gan: Israel Medical Association. 4: 790–793.
  16. ^ Burgess, Ian F.; Brown, Christine M.; Lee, Peter N. (10 June 2005). "Treatment of head louse infestation with 4% dimeticone lotion: randomised controlled equivalence trial". British Medical Journal. London: BMJ Publishing Group Ltd. 330 (7505): 1423. doi:10.1136/bmj.38497.506481.8F. PMC 558378. PMID 15951310. Retrieved 2008-01-03.
  17. ^ "Silcap". Oystershell NV. Archived from the original on April 3, 2010. Retrieved July 7, 2010.
  18. ^ PCT/EP2008/050417 Foamable composition for killing arthropods and uses thereof.
  19. ^ Janssens, Andre. "Silcap". Oystershell NV. Archived from the original on April 3, 2010. Retrieved July 9, 2010.
  20. ^ Mumcuoglu, Kosta Y.; Barker CS; Burgess IF; Combescot-Lang C; Dagleish RC; Larsen KS; Miller J; Roberts RJ; Taylan-Ozkan A. (2007). "International Guidelines for Effective Control of Head Louse Infestations". Journal of Drugs in Dermatology. 6 (4): 409–414. PMID 17668538.
  21. ^ "Indiana Teenager Critically Burned Trying to Kill Head Lice". FOX News. February 26, 2009.
  22. ^ Gasoline Lice Treatment at
  23. ^ "History of Carless, Capel & Leonard". Vintage Garage. 2008. Archived from the original on 2014-12-29. Retrieved 2014-12-28.