Mechanical removal Mechanically removing lice and nits can be an effective but time-consuming method. Because most eggs will be non-viable, their removal is often impractical and unjustified. An infestation may be eliminated by combing each day to remove the live lice (including those that have hatched since the previous day). Comb daily until no live lice are discovered for about two weeks. Use illumination, magnification and a good louse or nit comb to locate and remove the offending insects. Although the hair may appear 'peppered' with eggs, there generally are fewer than a dozen active lice on the head at any time. Adult female lice usually cement each egg to the base of a hair shaft near the skin. As the hair grows (from the base), these attached eggs are transported away from the scalp. Eggs more than one-half of one inch away from the scalp are nearly always hatched and do not, by themselves, indicate an active infestation.
Louse or nit combs can be useful in removing lice and eggs. Diverse types of fine-toothed combs may be included within packages of pediculicides or they may be purchased from virtually any drug store, pet supply store (often at a discount) or via the web. Some louse combs are better than others; their effectiveness depends on a) their composition (metal vs. plastic) and construction (length and spacing of the comb teeth), b) the texture of the hair to be combed, c) the technique used to comb, and d) the time and care expended in the effort. Whereas straight hair is usually readily combed, tight curls may present an impossible and impractical challenge. Hair should be cleaned and well-combed or brushed to remove tangles before attempting to use a louse comb. Clean the louse comb frequently to remove any caught lice or eggs. It may require several hours each night for several nights to tackle the problem. An entertaining video may help keep the child occupied during this exercise. Sit behind the child, and use a suitably bright light (and magnification if available), to inspect and comb through the hair, one small section at a time. Repeat until no more active lice are observed. Some parents report that water, vegetable oils or hair conditioners help lubricate the hair and ease the combing process; others report that these lubricants make it more difficult to see the eggs.
"Electronic" louse combs that resemble small bug "zappers", or those with oscillating teeth would seem to offer little advantage, if any, over a well-designed traditional louse comb. Teeth of these devices may not effectively reach to the scalp and may not kill or remove eggs.
Pyrethroid insecticides Infestations may be treated with shampoos containing permethrin or pyrethrins specifically labeled for use on people. Some formulations also contain a synergist, a chemical that may enhance the activity of the insecticide. As with any insecticide or drug, read and follow the label directions. Because these products seem to have limited ovicidal (egg-killing) activity, a second treatment is often necessary about 10 days later to target lice that hatch after the initial treatment. Susceptible lice do not fall from the hair or die immediately upon treatment with pyrethroids; one should wait until the next morning to determine the fate of treated lice. As is true of any pediculicide, pyrethroids do not remove the eggs from the hair.
Some physicians treat apparently resistant infestations with a prescription-strength pyrethroid (3 - 5%) preparation normally meant for treating scabies infestations. In our recently published article we report that some head lice in the United States are resistant to permethrin, and that higher doses of this insecticide generally were not more effective. Thus, prescription-strength pyrethroids are not likely to be effective. Although permethrin and pyrethrins differ in chemical structure, their mode of action is quite similar. Thus, we would anticipate that pyrethrins would also be ineffective in killing permethrin-resistant lice.
Non-pyrethroid insecticides Other insecticides should be avoided unless specifically prescribed by a physician. The organochlorine insecticide lindane, and the organophosphate insecticide malathion are two of the active agents within pediculicides available by prescription. The current susceptibility of these insects to lindane or malathion has not yet been analyzed in the United States. Prescription preparations containing these insecticides may be considered as alternative pediculicides if live lice persist after two treatments with pyrethroid-based pediculicides. Refer to our management flowcharts.
Use caution when dealing with any insecticidal agent, particularly on children. Read and follow label directions. Do not apply any insecticide or other chemical not specifically labeled for use on people. Well-intentioned parents treating their children with toxic or flammable substances have caused several deaths and poisonings.
Essential oils Numerous "home recipes" and commercial preparations are based on mixtures of essential oils, salts or other "natural" substances. Data is lacking to support the claims of their efficacy. Several formulations include substances that should not be used on the skin, and may not be registered for such use by government regulatory agencies (such as EPA or FDA).
Enzyme treatments The chemical structure of the "cement" that binds the egg to the hair is not well-defined. Nonetheless, it is an exceptionally stable substance that resists degradation by diverse chemicals. Several commercial products are advertised to "dissolve" the eggs or the cement by which the eggs are attached to the hair. We are not convinced of the effectiveness or safety of these products.
Antibiotics The guts of human lice contain a specialized organ that harbors an unusual type of bacteria. These bacteria may aid the louse in digesting the blood meal or by providing essential nutrients. Certain antibiotics may affect or eliminate these bacteria from the louse's gut, and body lice that have fed upon antibiotic-laden blood of people may be burdened and die. The effect of antibiotics on the health of head lice has yet to be determined conclusively. Physicians increasingly seem to prescribe combinations of the antibiotic agents trimethoprim and sulfamethoxazole (e.g. "Bactrim", 'septra") in attempts to treat head lice. We oppose this practice because these antibiotics are not approved as pediculicides, and they are valuable in fighting life-threatening infections. Their use for treating such a relatively innocuous condition as a louse infestation may accelerate the emergence or spread of bacterial resistance, thereby diminishing the usefulness of these antibiotics.
Antiparasitic drugs Diverse antiparasitic agents have been proposed for treating human lice, but none has been evaluated critically. The drug ivermectin, for example, is widely used in veterinary medicine as an antiparasitic agent, and is available for human use for treating infestations caused by certain worms; it is not approved for use against human lice. Accordingly, we suggest that such treatments be avoided.
Suffocating agents An increasingly popular "alternative" treatment involves the use of food-grade oils or hair gels in attempts to smother lice on the scalp. Many people have provided anecdotal reports of their successes with this old method, but we have also heard of nearly an equal number of failures. Virtually no data, however, is available to assess the efficacy of this technique. As with any hair conditioner, oils may lubricate and ease efforts to pass louse or nit combs through the hair. Olive oil (or any similar food-grade product) would seem intrinsically safe, but may have associated hazards, nonetheless. Oil may cause accidents (slips), and would be difficult to remove from the hair and scalp (detergents can cause irritation). Do not use motor or machine oils, as these materials can be harmful.
As a preliminary test to measure the effect of such agents on lice, we submerged six active lice in olive oil, and maintained an equal number of non-treated lice in a separate container. Lice removed from oil after one hour recovered, but those submerged for two hours succumbed. Non-treated lice survived for at least 18 hours. We have not repeated this test on active lice nor have we tested this treatment on nits. The results are simply of a very preliminary nature and should not be construed as solid evidence on which one would base treatment recommendations. It would be an error to extrapolate from data of such an informal test; therefore, we do not recommend the use of olive oil (or other such substances) as a treatment for head lice.
Heat The hot dry air produced by standard hand-held hair dryers may suffice to kill lice and their eggs on a person's hair. Use great care if you try this method, as the heated air from these devices can also easily scald the hair and the scalp. No precise values (treatment time, temperature, and distance from hair dryer) are available with which to base an objective treatment protocol. Heated curling irons, hair straighteners or similar devices may kill some lice and eggs, but may not safely be applied to hair nearest the skin where viable eggs are most abundant. A clothes dryer set a high heat or a hot pressing iron may effectively kill any lice or their eggs on pillowcases, sheets, nightclothes, towels and similar items that will not be damaged by this process. Combs, brushes, hats and other hair accessories in contact with an infested person should be washed in hot water each day to dislodge any lice or nits.
Freezing Lice and their eggs on inanimate objects (e.g. toys) may be killed by freezing temperatures. Objects that cannot be heated in a clothes dryer may be placed in a freezer (or outdoors if sufficiently cold). This treatment may require several days to be effective, depending on the temperature and humidity. Such treatment would rarely (if ever) be required.
Haircuts Lice will find little to grasp on a bald or shaved head. Although competitive swimmers who shave their heads generally need not be concerned about head lice, many parents may find this old-fashioned method to be aesthetically unappealing. Short hair is more readily searched for lice and eggs, but does not make the child invulnerable to infestation.
All three types of human lice may occasionally be found on the eyelashes or other facial hair. These lice should be mechanically removed with great care so as not to injure the eye; insecticides should be kept well clear of the eyes as well. Cosmetology practices and regulations often dictate that infested individuals be sent away by the barber or beautician, and any implements that contacted that person be properly cleansed.
Hair soaps, bleaches and dyes Washing the hair each day may dislodge a few active lice; the remaining lice and eggs will be unaffected (but clean). Although hair bleaches and dyes are meant for use on the scalp, they can be caustic. Data is lacking to assess the efficacy of these products against lice. Thus, use of these products in attempts to "treat" lice should probably not be considered. Assertions that dandruff shampoos are effective in removing lice are probably due to misidentification of dandruff as lice.
Do dogs and cats serve to maintain or transfer head lice? Pets are of no significance in maintaining or transmitting human lice, and should not be treated for head lice.
Should I clean my house or car? Head lice and their eggs soon perish if separated from their human host. Removed lice survive just a day or so, and the eggs generally lose viability within a week. The chances of a live head louse or egg becoming reunited with a person would seem remote exceptionally. Accordingly, Herculean steps to clean lice from the house or car by intensive washing or vacuuming will result in a cleaner space, but are unlikely to significantly facilitate the goal of eliminating the lice from those residing in the home. A child's car seat cover may benefit from vacuuming, as a few errant lice or eggs may temporarily lodge there and survive for a day or so.
What should be cleaned? Washing and drying (with heat) the pillowcases, sheets, nightclothes, towels and stuffed animals may possibly eliminate lice and eggs that might otherwise reinfest a family member. Combs, brushes, hats and other hair accessories in contact with an infested person should be washed in hot water each day to dislodge any lice and nits. Shared helmets and headphones in schools or recreational settings may rarely and transiently harbor an occasional louse or nit; the effort necessary to effectively inspect and clean these devices, however, is not likely warranted. Shared lockers or coat hooks probably pose even less risk as sources of contamination. Any lice or nits that might detach in a swimming pool would likely be removed by the pool filter or should otherwise perish before they have a chance to contact a person. Closing a swimming pool because of lice is a hysterical overreaction.
Should I use insecticides in the house to rid it of lice? Insecticidal treatments targeted at lice within the school or home, in vehicles, or to carpets and furniture are generally unwarranted, and unnecessarily expose occupants to insecticidal residues.
Can anything be used to repel lice? The application of any substance to the hair with an expectation of repelling lice is unwarranted and may neither be safe nor effective. Head lice do not seem to be readily acquired naturally, and they may pose less risk than any "repellent" product.
Search for head lice when hair is wet. Use a fine-toothed comb (or a louse comb), clear tape (to stick on hair to pick up nits), a magnifying glass, and a strong light.
Wet combing should be done every 2-3 days over a 2-week period, with small sections of hair, working out from the scalp. Some call this "bug busting," and it can be very effective.
If lice are found, treat with an anti-lice agent and repeat in 7-10 days to kill newly hatched nits.
How to use anti-lice agents: Over-the-counter treatment is available and should be used first. If after 2 applications, lice are still present, then prescription anti-lice agents may be needed from your doctor. Apply the anti-lice agent to dry hair for the time listed on the product (usually 10 minutes). Shampoo and rinse hair and comb as directed with a fine-toothed comb. Repeat anti-lice treatment in 7-10 days to kill nits that may have hatched.
Nonprescription anti-lice agents include Nix Lotion (permethrin 1%) and Rid, A200, and Pronto shampoos (pyrethrin products).
Check all household members and treat only if lice or nits are seen.
If a child is younger than 2 years, comb to remove lice and nits but do not use anti-lice agents.
Hair conditioners may coat or cover the lice, so they should not be used before applying anti-lice agents.
Wash all bed linens and clothing that have been in contact with the infested person in the past 2 days. Use hot water and the hot cycle in the dryer.
Some recommend that water be at least 140°F to effectively kill the lice and nits. Most hot-water heaters are set at 120°F for child safety. This lower temperature may be effective.
All nonwashable items such as stuffed animals should be placed in plastic bags for 2 weeks then opened outdoors. Dry cleaning may be an alternative.
Disinfect combs and brushes in hot water or alcohol. Soak for more than 5 minutes in very hot water (greater than 131°F or 55°C).
Vacuum floors and furniture, especially couches and areas used by children. Throw away the vacuum bag immediately.
Herbal therapy and oil treatments have not been proven to work.
Do not use gasoline, kerosene, or oils. Burns have occurred.
Do not shave the person's head. This drastic measure is not necessary.
If lice are seen in a school-aged child, notify the school nurse or teacher in order to limit the spread.