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Pediculicides are substances used to treat lice (Pediculus humanus capitus).[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).

The only agents approved by the FDA for treatment of pediculosis are lindane and malathion.[2]

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.[3][4][5][6]

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.[7][8][9]

Ivermectin (which can be given orally) has been shown to reduce levels of louse infestation.[10][11][12] Originally approved for onchocerciasis and strongyloidiasis,[2][13] Ivermectin is now approved by the FDA for pediculosis.[14]

Natural products[edit]

Natural products tested clinically and found to be safe and effective could be very important in the control of head lice, as the complexity of the active ingredients may prevent the rapid development of resistance. [4] They are more acceptable to some parents who are concerned with the use of chemical pediculicides. Several plant products such as aniseed, citronella, coconut, neem and tea tree oils offer promise for new compounds to treat head lice infestation. However, the number of clinical studies is very limited, and most have methodological problems such as lack of a comparison group.[5][15] Plain vaseline also works and is non-harmful, though messy: like all animals, lice need to breathe, and smothering hair with vaseline or other oily/fatty substances (like the aforementioned plant oils) for several hours will asphyxiate them. Removing the oily substance itself can be somewhat difficult; in such a case a highly-foaming soap will be needed. Vinegar is also effective and safe in the treatment of pediculosis. Hair is drenched in warm vinegar, and then a shower cap is put on in order to suffocate adult lice and erode egg walls (rendering them unviable). The cap should be worn overnight or at least for six hours.

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) ([3]). 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 class mates .[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]


Common rubbing alcohol, when applied to the head, has been known to kill both the adult lice and the eggs.[24][25] Ethanol (ethyl alcohol, common alcohol) is toxic to arthropods including lice and an external application of it is harmless to humans.[26] Alcohol can be used as a remedy for pediculosis either by using a fine comb and dipping it in alcohol before combing, which is simply a way to increase the effectiveness of combing by increasing the chances of killing any lice that the comb misses, or by soaking the head in a large quantity of alcohol and leaving it for one second, or a mixture of ethanol and the everyday hair conditioner can be made. Alcohol use, however, implies certain risks: the scalp can suffer irritations, for example, or it could get into the eyes and cause severe pain and discomfort, or it can be toxic to death if consumed.


A number of promising compounds are currently in development for the treatment of head lice. Approval of any of these products may make it much easier to treat head lice in the future.

  • Summers Laboratories is developing a benzyl alcohol-based treatment that kills by asphyxiation (Summer's Non-pesticide Lice Asphyxiator). This product is a water-soluble gel similar in consistency to a hair conditioner. It consists of a mixture of dermatological and cosmetic ingredients. The active ingredient is benzyl alcohol. The product was acquired by Sciele Pharma for distribution in the United States, Canada, and Mexico. The product was recently approved by the FDA and is being marketed under the brand name Ulesfia.
  • ParaPRO is developing a crème rinse containing a novel biologically derived pesticide, Spinosad.[27] The product, tentatively branded NatrOVA, is currently being tested in FDA approved clinical trials.


  1. ^
  2. ^ a b 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. 
  3. ^ 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. 
  4. ^ Mumcuoglu, KY; Miller, J. (1991). "The Efficacy of Pediculicides in Israel". Israel Journal of Medical Sciences (Jerusalem: Weizmann Science Press) 27 (10): 562–565. 
  5. ^ 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 (BMJ) (London: BMJ Publishing Group Ltd) 311 (7005): 604–608. PMC 2550649. PMID 7545045. Retrieved 2008-01-03. 
  6. ^ 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. 
  7. ^ 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. 
  8. ^ 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]
  9. ^ 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. 
  10. ^ 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. [dead link]
  11. ^ 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. 
  12. ^ 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. 
  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 (BMJ) (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. Retrieved July 7, 2010. 
  18. ^ PCT/EP2008/050417 Foamable composition for killing arthropods and uses thereof.
  19. ^ Janssens, Andre. "Silcap". Oystershell NV. 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. Retrieved 2014-12-28. 
  24. ^ [1]
  25. ^ [2]
  26. ^ JF Marriott. 2010. Pharmaceutical Compounding and Dispensing. p.77: p.77:"ALCOHOL. After water, this is probably the next most important solvent used pharmaceutically. Although ethanol (ethyl alcohol) is rarely used as a lone solvent for preparations for internal use, it is used in the manufacture of some of the galenicals used in pharmacy (e.g. tinctures, see Chapter 2). In extemporaneous dispensing it is normally used for the production of lotions for external application to unbroken skin. It is particularly useful if rapid evaporation is required (e.g. for insecticidal lotions applied to hair for the treatment of lice)..."
    Ethanol as an arthropod killing solution, e.g. Szinwelski, N., Fialho, V. S., Yotoko, K. S. C., Seleme, L. R., & Sperber, C. F. (2012). Ethanol fuel improves arthropod capture in pitfall traps and preserves DNA. ZooKeys, (196), 11–22. Advance online publication. "...It has been shown that at concentrations higher than 95%, commercial alcohol preserves DNA (Nagy 2010), but the use of highly concentrated commercial alcohol as a killing solution may be prohibitively expensive when needed in large quantities, such as in large-scale biodiversity sampling. In Brazil, for example, it is illegal to carry large amounts of commercial alcohol on long journeys, which could hinder its use in extensive field expeditions. Here we propose the use of ethanol fuel as a cheaper and logistically feasible alternative..."
    Sociedad Argentina de Pediatria. Actualización en pediculosis. "La cuasia amarga (palo amargo) se extrae de un arbusto que crece en el norte de la Argentina. El principio activo que se extrae de la madera es la cuasina y químicamente es un hidrocarburo soluble en alcohol. Popularmente se lo usa como repelente de piojos y como pediculicida. Es efectiva únicamente en solución alcohólica y no en solución acuosa. Así es tan efectiva como una solución pura de alcohol por lo cual se duda de su efecto pediculicida “per sé” y es irritativa."
  27. ^ Cueto, G. Mougabure; Zerba, E. N.; Picollo, M. I. (May 2006). "Permethrin-Resistant head Lice (Anoplura: Pediculidae) in Argentina Are Susceptible to Spinosad". Journal of Medical Entomology (Entomological Society of America) 43 (3): 634–635. doi:10.1603/0022-2585(2006)43[634:PHLAPI]2.0.CO;2.