The treatment of human lice is the removal of
head lice
The head louse (''Pediculus humanus capitis'') is an obligate ectoparasite of humans. Head lice are wingless insects that spend their entire lives on the human scalp and feeding exclusively on human blood. Humans are the only known hosts of thi ...
parasites from human hair. It has been debated and studied for centuries. However, the number of cases of human
louse
Louse ( : lice) is the common name for any member of the clade Phthiraptera, which contains nearly 5,000 species of wingless parasitic insects. Phthiraptera has variously been recognized as an order, infraorder, or a parvorder, as a result o ...
infestations (or
pediculosis
Pediculosis is an infestation of lice from the sub-order Anoplura, family Pediculidae. Accordingly, the infestation with head lice is named pediculosis capitis, while this with body lice, pediculosis corporis. Although ''pediculosis'' in humans ma ...
) has increased worldwide since the mid-1960s, reaching hundreds of millions annually.
There is no product or method that assures 100% destruction of the eggs and hatched lice after a single treatment. However, there are a number of treatment modalities that can be employed with varying degrees of success. These methods include chemical treatments, natural products, combs, shaving, hot air, and
silicone
A silicone or polysiloxane is a polymer made up of siloxane (−R2Si−O−SiR2−, where R = organic group). They are typically colorless oils or rubber-like substances. Silicones are used in sealants, adhesives, lubricants, medicine, cooking ...
-based lotions.
Treatment is recommended only after a clear diagnosis since all treatments have potential side effects.
Louse eggs hatch 6–9 days after
oviposition
The ovipositor is a tube-like organ used by some animals, especially insects, for the laying of eggs. In insects, an ovipositor consists of a maximum of three pairs of appendages. The details and morphology of the ovipositor vary, but typical ...
. Therefore, a common recommendation is to repeat treatment with a
pediculicide
The treatment of human lice is the removal of head lice parasites from human hair. It has been debated and studied for centuries. However, the number of cases of human louse infestations (or pediculosis) has increased worldwide since the mid-1960s, ...
at least once after 10 days, when all lice have hatched.
[ ] Between the two treatments (Days 2–9) the person will still be infested with lice that hatch from eggs not killed by the anti-louse product. Between the treatments, it is advised to wet the hair and comb daily with a louse-comb to remove the hatching lice. If no living lice are found, the treatment was successful, even if nits (eggs) are visible on the hair. If living lice are still present, the treatment is repeated using an anti-louse product with a different active ingredient. This is kept in the hair for 2 hours and then rinsed out, with the head and hair cleaned before sleep. Prophylactic treatment with pediculicides is not recommended.
Medications
Insecticides used for the treatment of head lice include
lindane
Lindane, also known as ''gamma''-hexachlorocyclohexane (γ-HCH), gammaxene, Gammallin and benzene hexachloride (BHC), is an organochlorine chemical and an isomer of hexachlorocyclohexane that has been used both as an agricultural insecticide and ...
,
malathion
Malathion is an organophosphate insecticide which acts as an acetylcholinesterase inhibitor. In the USSR, it was known as carbophos, in New Zealand and Australia as maldison and in South Africa as mercaptothion.
Pesticide use
Malathion is a pesti ...
,
carbaryl
Carbaryl (1-naphthyl methylcarbamate) is a chemical in the carbamate family used chiefly as an insecticide. It is a white crystalline solid previously sold under the brand name Sevin, which was a trademark of the Bayer Company. The Sevin tradem ...
,
pyrethrum
''Pyrethrum'' was a genus of several Old World plants now classified as ''Chrysanthemum'' or ''Tanacetum'' which are cultivated as ornamentals for their showy flower heads. Pyrethrum continues to be used as a common name for plants formerly inclu ...
,
piperonyl butoxide
Piperonyl butoxide (PBO) is a pale yellow to light brown liquidNational Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Tr ...
,
permethrin
Permethrin is a medication and an insecticide. As a medication, it is used to treat scabies and lice. It is applied to the skin as a cream or lotion. As an insecticide, it can be sprayed onto clothing or mosquito nets to kill the insects that t ...
,
phenothrin
Phenothrin, also called sumithrin and d-phenothrin, is a synthetic pyrethroid that kills adult fleas and ticks. It has also been used to kill head lice in humans. d-Phenothrin is used as a component of aerosol insecticides for domestic use. It is ...
,
bioallethrin
Bioallethrin is a brand name for an ectoparasiticide. It consists of two of the eight stereoisomers of allethrin I in an approximate ratio of 1:1. The name ''Bioallethrin'' is a registered trademark of Sumitomo Chemical.
''Esbiothrin'' (CAS number ...
, and
spinosad
Spinosad is an insecticide based on chemical compounds found in the bacterial species ''Saccharopolyspora spinosa''. The genus ''Saccharopolyspora'' was discovered in 1985 in isolates from crushed sugarcane. The bacteria produce yellowish-pink ae ...
.
Many of the pediculicides in the market are either not fully effective or are ineffective when they are used according to the instructions.
Pediculicides may rapidly lose their efficacy because of the development of resistance. Resistance of head lice to insecticides such as
lindane
Lindane, also known as ''gamma''-hexachlorocyclohexane (γ-HCH), gammaxene, Gammallin and benzene hexachloride (BHC), is an organochlorine chemical and an isomer of hexachlorocyclohexane that has been used both as an agricultural insecticide and ...
,
malathion
Malathion is an organophosphate insecticide which acts as an acetylcholinesterase inhibitor. In the USSR, it was known as carbophos, in New Zealand and Australia as maldison and in South Africa as mercaptothion.
Pesticide use
Malathion is a pesti ...
,
phenothrin
Phenothrin, also called sumithrin and d-phenothrin, is a synthetic pyrethroid that kills adult fleas and ticks. It has also been used to kill head lice in humans. d-Phenothrin is used as a component of aerosol insecticides for domestic use. It is ...
and
permethrin
Permethrin is a medication and an insecticide. As a medication, it is used to treat scabies and lice. It is applied to the skin as a cream or lotion. As an insecticide, it can be sprayed onto clothing or mosquito nets to kill the insects that t ...
has been reported.
A 2021 systematic review and meta-analysis found that the mean frequency of pyrethroid resistance of lice was 77% globally, and even 100% in several countries (Australia, England, Israel, and Turkey).
It concluded that treatment with current insecticides may not be effective and is likely the cause of increased levels of infestations.
[ ]
Ivermectin
Ivermectin (, '' EYE-vər-MEK-tin'') is an antiparasitic drug. After its discovery in 1975, its first uses were in veterinary medicine to prevent and treat heartworm and acariasis. Approved for human use in 1987, today it is used to treat inf ...
by mouth has been shown to reduce levels of
louse infestation.
Ivermectin
Ivermectin (, '' EYE-vər-MEK-tin'') is an antiparasitic drug. After its discovery in 1975, its first uses were in veterinary medicine to prevent and treat heartworm and acariasis. Approved for human use in 1987, today it is used to treat inf ...
is approved by the U.S.
Food and Drug Administration
The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is respon ...
(FDA) for pediculosis.
Agents approved by the FDA for treatment of pediculosis include
abametapir
Abametapir, sold under the brand name Xeglyze, is a medication used for the treatment of head lice infestation in people six months of age and older.
The most common side effects include skin redness, rash, skin burning sensation, skin inflamm ...
, topical ivermectin lotion, lindane, malathion, permethrin, and piperonyl butoxide with pyrethrins.
Heated air
![LouseBuster](https://upload.wikimedia.org/wikipedia/commons/0/01/LouseBuster.JPG)
A standard home
blow dryer
A hair dryer, hairdryer or blow dryer is an electromechanical device that blows ambient or hot air over damp hair to speed the evaporation of water to dry the hair. Blow dryers enable better control over the shape and style of hair, by accelera ...
will kill 96.7% of eggs with proper technique.
To be effective, the blow dryer must be used repeatedly (every 1 to 7 days since eggs hatch in 7 to 10 days) until the natural life cycle of the lice is over (about 4 weeks).
A number of commercial head lice treatment companies across the country offer a heated air treatment.
Combing
![Adriaen Brouwer - The delousing](https://upload.wikimedia.org/wikipedia/commons/7/77/Adriaen_Brouwer_-_The_delousing.jpg)
A special fine-toothed comb that can pick out lice is used. For a treatment with louse comb alone, it is recommended to comb the hair for an hour to an hour and a half (depending the length and type of the hair) daily or every second day for 14 days. Wetting the hair especially with water and shampoo or conditioner will facilitate the combing and the removal of lice, eggs and nits.
[
]
Electronic louse combs use a small electrical charge to kill lice. The metal teeth of the comb have alternating positively and negatively charged tines, which are powered by a small battery. When the comb is used on dry hair, lice make contact with multiple tines of the fine-toothed comb, thereby closing the circuit and receiving an electrical charge. A non-peer-reviewed letter has been published in a dermatology journal claiming effectiveness based on personal experience (total of 6 uses).
[
]
Procedures
Shaving the head or cutting the hair extremely short can be used to control lice infestation. Short hair, baldness, or a shaven scalp are generally seen as a preventive measure against louse infestation. This will also eliminate – particularly if maintained for the length of the parasites' reproductive cycle – louse infestation.
Infestation with lice is not a serious disease and the medical symptoms are normally minimal. In any case, health providers and parents should try not to create emotional problems for children during examination and treatment.
Shaving of the area above and behind the ears and the upper part of the neck while leaving the crown of the head with hair is commonly used to prevent lice among tribes in Africa, Asia, and America (in America –
Mohawk Mohawk may refer to:
Related to Native Americans
*Mohawk people, an indigenous people of North America (Canada and New York)
*Mohawk language, the language spoken by the Mohawk people
*Mohawk hairstyle, from a hairstyle once thought to have been t ...
style).
School treatment
![Fig](https://upload.wikimedia.org/wikipedia/commons/b/b3/Fig._5._Louse_nits.jpg)
Schools in the
United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
,
Canada
Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...
, and
Australia
Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...
commonly exclude infested students, and prevent return of those students until all lice, eggs, and nits are removed.
[
] This is the basis of the "no-nit policy". Data from a primarily American study during 1998–1999 found that no-nit policies were present at 82% of the schools attended by children suspected of louse infestation.
A separate 1998 survey revealed that 60% of American
school nurses felt that "forced absenteeism of any child who has any nits in their hair is a good idea."
A number of health researchers and organizations object to the no-nit policy.
[
][
][
] Opponents to the no-nit policy mention that visible nits may only be empty egg casings which pose no concern as transmission can only occur via live lice or eggs.
This has led to the perception that the no-nit policy serves only to ease the workload of school nurses and punish the parents of infested children.
Proponents of the no-nit policy counter that only a consistently nit-free child can be reliably shown to be infestation-free.
[
] That is, the presence of nits serves as an indirect proxy for infestation status. Proponents argue that such a proxy is necessary because lice screening is prone to false negative conclusions (i.e., failure to find lice present on actively infested children).
[
] For example, a 1998 Israeli study found that 76% of live lice infestations were missed by visual inspection (as verified by subsequent combing methods).
[
] Although lice cannot fly or jump, they are fast and agile in their native environment (i.e., clinging to hairs near the warmth of the scalp),
and will try to avoid the light used during inspection.
[
] Louse colonies are also sparse (often fewer than 10 lice), which can contribute to difficulty in finding live specimens.
Further, lice populations consist predominantly of immature nymphs,
[
] which are even smaller and harder to detect than adult lice.
Alternative medicine
Tea tree oil
Tea tree oil, also known as melaleuca oil, is an essential oil with a fresh camphoraceous odor and a colour that ranges from pale yellow to nearly colourless and clear. It is derived from the leaves of the tea tree, ''Melaleuca alternifolia'', ...
has been promoted as a treatment for head lice; however, evidence of its effectiveness is weak.
A 2012 review of head lice treatment recommended against the use of tea tree oil for children because it could cause skin irritation or allergic reactions, because of
contraindication
In medicine, a contraindication is a condition that serves as a reason not to take a certain medical treatment due to the harm that it would cause the patient. Contraindication is the opposite of indication, which is a reason to use a certain tre ...
s, and because of a lack of knowledge about the oil's safety and effectiveness. Other home remedies such as putting vinegar, isopropyl alcohol, olive oil, mayonnaise, or melted butter in the hair have been partially disproven, The use of plastic bags may be dangerous. Similarly, the
Centers for Disease Control and Prevention
The Centers for Disease Control and Prevention (CDC) is the national public health agency of the United States. It is a United States federal agency, under the Department of Health and Human Services, and is headquartered in Atlanta, Georgi ...
reports that swimming has no effect on treating lice, and can in fact harm the treatment by commercial products.
Ethanol
Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an Alcohol (chemistry), alcohol with the chemical formula . Its formula can be also written as or (an ethyl ...
(ethyl alcohol, common alcohol) is toxic to arthropods including lice and an external application of it is harmless to humans.
Gasoline or kerosene
The use of
kerosene
Kerosene, paraffin, or lamp oil is a combustible hydrocarbon liquid which is derived from petroleum. It is widely used as a fuel in aviation as well as households. Its name derives from el, κηρός (''keros'') meaning "wax", and was regi ...
or
gasoline
Gasoline (; ) or petrol (; ) (see ) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most spark-ignited internal combustion engines (also known as petrol engines). It consists mostly of organic co ...
for prevention or treatment of lice is dangerous due to the inherent fire hazard.
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
Dermatitis is inflammation of the skin, typically characterized by itchiness, redness and a rash. In cases of short duration, there may be small blisters, while in long-term cases the skin may become thickened. The area of skin involved can v ...
(i.e. irritation of the scalp).
Before
gasoline (Petrol) was used as fuel, it was sold in small bottles as a treatment against lice and their eggs. At that time, the word ''Petrol'' was a trade name.
[
]
References
Further reading
*
External links
Centers for Disease Control and Prevention: Division of Parasitic DiseasesNational Pediculosis Association
{{DEFAULTSORT:Treatment Of Human Head Lice
Lice
Medical treatments