Head Lice: Things that go itch in the night…or anytime, really

| Posted On Sep 28, 2011 | By:

Kids are back in school, sharing books, pencils, and jump ropes…and they could also be sharing head lice!

Head lice definitely cause heightened anxiety in parents and schools, but in actuality, they do not spread disease, are not a health hazard and are not a sign of poor hygiene.  Although difficult to accept for those affected, lice infestation is rather benign.  (Of course, the scratching isn’t so easy to deal with!)

Who is affected?

Head lice, or “pediculosis capitis,” are found worldwide, and infestations occur among all socioeconomic backgrounds.  An estimated 6 to 12 million infestations of head lice occur in the U.S. each year.  Infestation is most common among children 3 to 12 years of age.  In fact, excluding the common cold, head lice affects more elementary school students in North America than all other communicable diseases combined.

What is a head louse? 

The head louse is a grayish-white insect 2 to 4 mm in length. It is about the size of a sesame seed.  Both sexes are equipped with “mouth” parts adapted to sucking blood, as well as six legs able to grasp hairs. The life span of the female is about one month. Once mature, she lays 7 to 10 eggs each day.

A louse produces a glue-like substance that cements the eggs 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. After hatching, egg cases (also called “nits”) become white and more visible. The nymphs mature over the next 8-12 days. Once adults, they can mate and the cycle starts over again.

How are lice transmitted?

The most likely form of transmission is direct contact with the scalp. Lice cannot fly, hop or jump. They can only crawl.  It is also uncertain as to how long adult lice can survive without a host – sources give ranges from 24 hours up to 48-55 hours.  We do know that the eggs cannot hatch at an ambient temperature lower than that of the scalp.

Other theories on how they spread include cross-transfer from articles of clothing on adjacent hooks and shared combs, hats, headphones, or towels. However, this type of transfer is rare.  Also know that pets are not sources of transfer.

How do I know if my child has lice?

It can be hard to know, as most lice infestations are asymptomatic. Some children affected may even house a large number with no apparent symptoms. Itching results from sensitization to the louse’s saliva. However, this sensitization may take up to 4 to 6 weeks to materialize. Scratching can lead to secondary bacterial infection like impetigo. Pediatricians and parents should be suspicious that lice are present when children suffer from skin infections near the neck and ears.

What is the best way to diagnose lice? 

The diagnosis is made by seeing live lice. However, this can be an arduous task given that they avoid light and crawl quickly. Studies have revealed that using a louse comb is more efficient for diagnosis than visual inspection. Some experts suggest that wet combing (with water, oil or conditioner as a lubricant) may be better than the dry technique, but this has not been compared in clinical studies.

Nits may be more easily noticed than live lice. However, examiners tend to mistake hair casts, dandruff, and debris for nits. Nits are firmly attached to the hair shaft and are much harder to remove than these other entities. Yet, nits without lice do not automatically indicate an active infestation. Nits may last for months despite successful treatment.

How do I prevent lice?

How do I treat lice?

Once a visual diagnosis of head lice has been made, treatment with a pediculicide, a topical shampoo-like treatment, should begin.  A listing of pediculicides and more information on each type of product is below

Since no treatment is 100% effective, manual removal of nits after treatment is recommended, using the following procedure:

Combing should be continued until no lice are found in each session, with repeat sessions every three to four days for several weeks, continuing for two weeks after any session in which a large, adult louse is found. The procedure may take 15 to 30 minutes.

What are the topical treatments available?  

There are several products available in both prescription and over the counter forms to treat lice.  Some families comment that such treatments are unsuccessful.  It is more likely that the product’s application is ineffective rather than the product itself; making sure that enough product is applied and at the correct interval is essential.  Children with long hair may need more than what is indicated on the product directions; parents can apply four ounces of a product for every six inches of hair. Other potential problems include reinfestation or resistance to medications.

For younger patients, or if the parent cannot afford or does not wish to use a pediculicide, manual removal via wet combingor an occlusive method may be recommended, with emphasis on careful technique and the use of 2 to 4 properly timed treatment cycles.

Permethrin 1% lotion (Nix®)  According to the AAP, initial treatment should begin with Permethrin 1% lotion. It is the most studied topical pediculicide in the United States. It is the least toxic as well. It is available over the counter as Nix®.  Side effects can include redness, itching and swelling.  It should be applied to damp hair that has been shampooed and towel dried. After ten minutes, it should be rinsed off. A residue is left on the hair that kills nymphs that may emerge from the 20-30% of eggs not killed by the first application. It should be repeated in 7 to 10 days if live lice are visualized.  Some experts now recommend a standard re-application at day nine.
Pyrethrins Plus Piperonyl Butoxide (RID®) This treatment, also known as RID®, is made from extracts of chrysanthemums and piperonyl butoxide. It should be applied for 10 minutes before rinsing. However, it should be applied to dry hair. It does not leave any residue on hair and does need a re-application, preferably at day nine. Speak with your pediatrician’s office first before using.  Pediatricians should be aware of local resistance patterns, as high level of resistance in some communities may not make it a first-line therapy.
Benzyl Alcohol 5%  This is a newer medication for lice that was approved by the FDA in 2009 for children older than six months of age. The brand name is Ulesfia™. It is available by prescription only.  It kills lice by asphyxiation.  Two studies have shown that 75% of patients were free of lice at 14 days post treatment. The most common side effects are itching, redness and eye irritation. It should be applied for ten minutes and repeated in seven days. It is not considered first-line treatment at this time unless resistance is proven and the child is older than 6 months.
Lindane 1%  Known as Kwell®, this has been a lice treatment since the 1950s. However, it should be used with caution in children due to side effects. The American Academy of Pediatrics does not recommend its use.
Malathion 0.5%  This topical medication, commonly known as Ovide®, is an organophosphate that is highly flammable and toxic if accidentally ingested. Its use and safety has not been established in children less than six years of age and would not be a good choice as a first-line therapy, but does have a role in resistant cases.
Spinosad 0.9% (Natroba™) Natroba™ is a brand new FDA-approved topical medication for the treatment of head lice in children over the age of four years.  It requires a prescription.  Its active ingredient is spinosad, a compound derived from a soil microbe. This new medication shows promise, providing superior efficacy against permethrin 1% in initial clinical trials. In addition, it claims it can be used without the need for nit combing. A major drawback is that it contains benzyl alcohol; it is therefore not recommended for use in infants below the age of 6 months. The most common adverse side effects are application site redness and irritation as well as redness and irritation of the eyes.

Are there any other treatments for killing lice?

Asphyxiation:  There are no randomized controlled studies that have investigated the use of occlusive agents. However, such agents used to asphyxiate the lice, are commonly used.  The most effective option may be petrolatum jelly. One can apply 30 to 40 grams of petrolatum jelly to scalp, wear a shower cap and leave overnight. Daily vigorous shampooing for 10 more days is essential to remove remaining residue. The thick nature of the jelly may obstruct the respiratory system in the louse and actually suffocate it. Petrolatum jelly causes higher egg mortality compared to other agents like olive oil, cetaphil cleanser, melted butter, mayonnaise, and vinegar.

“Natural” Products: Essential oils have been widely used for the treatment of head lice and this may be an attractive option for families who would like to avoid pediculicides. However, they are not required to meet the same FDA efficacy and safety standards as pharmaceuticals and their production can be variable.  The effects, therefore, may be harder to reproduce, and their safety and efficacy cannot be measured as it can with medications. HairClean 1-2-3 (anise, ylang-ylang,coconut oils, and isopropyl alcohol) was found to be at least as effective as Nix by one investigator. Although many plants naturally produce insecticides that may be synthesized for use by humans, the possibility of toxic effects exists as well.

Are there oral treatments for lice?

There are a few oral medications that have not been approved by the FDA as a pediculicide yet show promising results.  Sulfamethoxazole-trimethoprim, an oral antibiotic known as Bactrim, has been referenced as an effective lice treatment. It may be even more effective if used with topical permethrin than either one alone. However, given the potential risks with the medication, the consensus at this time is to opt for topical permethrin instead.

Ivermectin, a medication used to treat worms, may be effective for lice. A single oral dose at day one and day 10 may be effective; it, however,  is not recommended for small children.

What if my child gets diagnosed at school?

According to the American Academy of Pediatrics (AAP), when a child is diagnosed at school they can remain in school but should start treatment once home.

When can my child return to school?

The AAP states that no child should be restricted from school due to head lice. Most researchers recommend that schools should abandon “no nits” policies. It is felt that children can return to school immediately after completion of the first application of a topical treatment or after the first wet combing session.

How should I protect my other children from getting lice?

All household members should be checked. If there are any live lice or nits within 1 cm of the scalp, the affected person should be treated. Bunkmates should be treated regardless of scalp findings. Given that the louse is unlikely to survive beyond 48 hours, only washing items that came in contact with the affected head 48 hours before treatment is needed. Washing items with hot water at least 130ºF is necessary. Items such as carpets and furniture can be vacuumed. Items that can’t be washed can be dry cleaned or placed in a sealed plastic bag for two weeks.

A case of head lice may seem at first overhwleming, but as the American Academy of Pediatrics has summarized, a little calm and commonsense can go a long way.



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About Dr. Brittanny Boulanger

Joined Harvard Vanguard: 2005 Undergraduate School: Dartmouth College, Hanover, NH Medical School: University of Massachusetts Medical School, Worcester, MA Internship: Golisano Children's Hospital, Rochester, NY Residency: Golisano Children's Hospital, Rochester, NY Board Certification: Pediatrics Hospital Affiliations: Children's Hospital, Boston, MA; Winchester Hospital, Winchester, MA Clinical Interests: Newborn medicine and adolescent medicine Personal Interests: Running, soccer, hiking, skiing, travel and spending time with her two young children.

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