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Preventing and Managing Lice Infestations
A lice infestation in your child’s school or circle of friends is cause for preventative measures rather than alarm. Nightly head inspections under good light will enable you to detect and promptly remove lice before they become a full-scale problem. Avoid misdiagnosis and unnecessary treatment by understanding the lice life cycle and knowing how to differentiate lice eggs – called ‘nits’ – from flakes of dry scalp and other debris. With know-how, a few simple tools, and a some patience, you can make sure that lice are gone before they take over.
If you have an active infestation, use both treatment and preventative measures to successfully eradicate lice outbreaks and prevent recurrence.
Important: Lice Cannot Live on Family Pets so don’t treat your pets!
The Life Cycle of Head Lice
Head lice are found worldwide and spend their entire lives on the heads of people, biting the scalp to feed on blood. They cause intense itching, usually on the back of the head. Lice can live no more than two days off the head of a person. They go through a few distinct stages to complete a month-long life cycle: egg (nit), larva (nymph), and adult. Because they cannot jump or fly, lice are spread only through direct contact with an infested person’s head hair or objects that have stray, infested hairs, like a hairbrush or a hat.
Female lice lay their tiny, oval-shaped nits next to the scalp at the base of hair shafts, effectively gluing them to the hair. They hatch in 7-11 days, by which point the hair has grown about 2-3 mm away from the scalp. Young lice are called nymphs and feed on human blood just like adults. About 7-10 days after hatching, lice reach maturity without forming a cocoon. Both male and female adults continue to feed while females lay eggs, beginning the cycle anew. From egg to mature female, the lice life cycle is about 25 days.
Identification
Correct identification of lice is essential to successful treatment and to avoiding unnecessary treatment. A study published by researchers at the Harvard School of Public Health in 2000 showed that parents, health care workers, and school officials frequently diagnose lice where none are present – 41% of more than 600 respondents misdiagnosed lice infestations. Avoid the cost and potential hazards of treatment by first confirming that those little white bits on the scalp truly are lice and not dandruff, another type of insect, or bits of debris.
Low Impact Approaches
Treating head lice requires a number of steps to ensure that you remove lice at all stages in their life cycle. Once you resolve an infestation, check children’s heads weekly to catch a recurrence before it requires full treatment. A nit comb is normally all that’s needed to prevent re-infestation. Let those who’ve been in recent contact with your household know as soon as you discover lice.
Because no shampoo can kill all nits, physical removal is essential to resolving a lice infestation, and to preventing re-infestation. A comb that is made for de-lousing is the most effective tool for nit removal. A lice comb, also called a nit comb, is designed to remove lice in all stages of life – nits, nymphs, and adults – from the hair and scalp. Widely available metal combs, such as the LiceMeister brand, are extremely effective and can eliminate the need for additional hair treatment when used daily. Plastic nit combs do not work as well as metal.
Start with clean, conditioned, towel-dry hair. Use a regular comb to remove snarls. Set up with a bright lamp or a sunlit window, plenty of hair clips, a sealable bag or container for the lice and stray hair you remove, and tissue to wipe the comb.
Systematically run the lice comb through the hair from the scalp to the ends. Check for any lice caught in the comb after each section and wipe off with the tissue. A hot, soapy water dip can be used in place of a wipe. Clip each section of hair out of your way as you work.
Finish up with a full rinse and complete dry, removing any visible nits you find as you dry the hair. Seal and dispose the bag with lice and infested hair. Boil the lice comb or soak in hot, soapy water for 15 minutes. Remove debris from between the tines using dental floss or an old toothbrush if the comb didn’t come with a cleaning device.
A study published in the British Medical Journal in 2005 showed that combing out the hair with a fine-toothed comb (the “Bug Buster”) immediately after using conditioner worked better than a single treatment of an over-the-counter insecticide.
Safety scissors can be used to clip out individual hair that has nits, as an alternative to a lice comb. Follow the same methodical procedure as with a lice comb, but use a regular comb or your fingers to inspect each section of hair. Additionally, cutting your child’s hair short will enable easier, more certain removal of lice with a lice comb.
The UC-IPM Department’s Lice Guidelines suggest that regular shampoos containing coconut or olive oil as active ingredients may kill adult lice and nymphs (but not nits). Treat lice with shampoo every three days for 2 weeks to kill newly hatched lice.
Items that need cleaning at the start of an infestation include carpets, upholstered furniture, bedding, clothing, and objects that have been in contact with the head (car seats, bike helmets, headphones, and stuffed animals). Everyday cleaning methods are sufficient to remove stray hairs that may have nits. There is no need for special chemical treatment around your home, as lice are generally confined to the head. Also, they cannot live on family pets.
Launder bedding and clothing in hot water – at least 140° – and use a hot drier. For any items that can’t be laundered, like hair brushes and stuffed animals, freeze them for 10 hours at 5° or colder. Vacuum carpets, upholstered furniture, and car seats for stray hairs.
Lice Control Pesticide Products
Head lice infestations can be eliminated without the use of highly toxic pesticides, but you and your physician may determine that a chemical treatment is called for. Avoid using lindane-containing products, for which the FDA has issued a Public Health Advisory (see Regulatory Update below for details).
Potential Consequences of Lice Control Pesticides
Recognize that when you use lice control pesticides, you should be ready to deal with these potential consequences:
- Exposure to potentially hazardous chemicals through skin, eyes, and lungs.
- Accidental poisoning due to overuse or misuse of pesticide products, especially in children, elderly patients, and patients with medical conditions that make them more susceptible to chemical toxicants.
- Decreased effectiveness of lice treatment products due to development of resistance in lice populations.
- Contribution to water pollution in your community.
Precautions to Take When Using Lice Control Pesticides
If you determine that pesticides are necessary, take these precautionary steps to reduce the potential for adverse effects:
- Always read and follow the label instructions on pharmaceutical pesticide products.
- Use only FDA-approved pharmaceutical products and review all labels and guidelines, even if you have used the same product in the past.
- Discuss potential health hazards with your doctor or pediatrician.
- Once you have an infestation under control, evaluate the need for continued pesticide use. Each use of a pesticide contributes to long-term reduction in its effectiveness as lice develop resistance to the chemical.
Comparison of Lice Control Pesticide Active Ingredients
If you choose to use a pesticide treatment, only do so if you have confirmed an active infestation (adult lice plus viable eggs). The table below provides an overview of available chemical treatments and the potential hazards associated with their use.
| Active Ingredient (Brand Names) | Hazards | Product Formulation |
|---|---|---|
| Benzyl alcohol* (Ulesfia) | Skin and eye irritant. Not known to cause long-term harm. | Lotion |
| Lindane* (Kwell) | Highly toxic to the human nervous system and has been implicated as the cause of death from lice treatments. May cause skin or eye irritation. Persistent pollutant in wastewater and fatty tissues of people exposed to it. FDA Black Box warning on label. Reasonably Anticipated to be a Human Carcinogen by the NIH. No longer recommended by the American Academy of Pediatrics. Resistance is an issue for effectiveness in some areas. | Shampoo, Lotion |
| Malathion* (Ovide) | Toxic to the nervous system and classified by the EPA as a possible carcinogen. Can irritate skin and eyes. Resistance is an issue for effectiveness in some areas. | Lotion |
| Permethrin (Nix) | Toxic to the nervous system. Classified by EPA as a Likely carcinogen. Some evidence for endocrine disruption. Resistance is an issue for effectiveness. | Lotion |
| Pyrethrins, combined with piperonyl butoxide (Rid, Triple X, Pronto) | Toxic to the nervous system. Classified by EPA as a Possible carcinogen. Can trigger allergic reactions and asthma. Resistance is an issue for effectiveness. | Shampoo, lotion |
| Spinosad* (Natroba) | Can cause skin and eye irritation. US EPA rates it as Not Likely to Be a Human Carcinogen. | Lotion |
| * Available by prescription only | ||
Regulatory Updates on Lice Treatments
EPA versus FDA: Who regulates lice treatments?
Typically, the Environmental Protection Agency (EPA) regulates pesticide products for use in the United States. The Federal Drug Administration (FDA) regulates products defined as drugs under the Federal Food, Drug and Cosmetic Act. In some cases, products containing pesticides are used as pharmaceutical treatments for pests that plague humans, as is the case with lice treatments. Prior to 1994, some of the over-the-counter lice treatments were regulated by EPA, while prescription products were regulated by FDA. In 1994, an FDA rule resulted in all EPA-registered products for lice being transferred to FDA jurisdiction. The rule also caused over-the-counter aerosol products to be removed from the market.
Lindane: A controversial lice treatment chemical
In addition to its use against lice and scabies, lindane was used as an insecticide on U.S. farms from 1951 until 2006, when the U.S. EPA cancelled all agricultural uses in recognition of the adverse impacts lindane has on human and environmental health. Though controversial, pharmaceutical use to treat lice and scabies has continued both abroad and in the U.S., but with increasingly stricter rules issued by the FDA in 1995 and 2003. California is the only U.S. state that has banned pharmaceutical use of lindane, effective in 2002.
The FDA issued a Public Health Advisory on lindane-containing products in 2003, requiring a black box warning label emphasizing its potential for neurotoxicity, particularly in infants, children, the elderly, individuals with other skin conditions, and those weighing less than 110 pounds. The warning advised that lindane only be used in patients who cannot tolerate or have failed other first-line treatments for lice and scabies and that it only be used a single time. The Advisory concludes:
Lindane products should be prescribed carefully, and quantities prescribed should be limited to amounts for a single application. Patients are at risk for serious neurologic adverse events, and even death, particularly with early retreatment. It is not known how soon after administering one dose of Lindane that a second dose can be safely administered. Post-treatment itching is common, especially in the treatment of scabies and does not necessarily indicate treatment failure.
In addition to having the potential for neurological, liver, and kidney harm – especially in children–lindane persists in the environment for many years and accumulates in the fatty tissues of people and wildlife that are exposed through food, water, and air. This is of particular concern in light of its status as Reasonably Anticipated to be a Human Carcinogen, according to the National Institutes of Health.
Some public health advocates, pediatricians, and congressional representatives continue to push for a total ban on lindane. Most recently, congressional representative Ed Markley of Massachusetts sent a letter to FDA Commissioner Hamburg in May 2012 requesting that the agency consider a ban on pharmaceutical use in light of documented hazards and the positive results reported from California’s ban. A 2008 study appearing in Environmental Health Perspectives reviewed the ecological and clinical outcomes of the California ban on lindane, concluding that the chemical’s presence in wastewater had been measurably reduced, calls to the poison control system about lindane had declined, and that a large majority of pediatricians reported no difficulty with overall control of headlice.
References and Additional Resources
- Centers for Disease Control: Head Lice. Recognition and treatment.
- University of California, Davis IPM Online: Pests of homes, structures, people and pets.
- National Pediculosis Association, Inc.: A nonprofit that provides information, advisories, and news about identification and treatment of lice and scabies. Supported in part by sales of its branded LiceMeister lice comb.
- National Pesticide Information Center: Provides objective, science-based information about lice pesticides and other control methods to facilitate informed decisions.
- U.S. Food and Drug Administration: Regulates all over-the-counter and prescription pesticide products used for treatment of head lice and provides important safety information to consumers.
