Head lice are tiny insects that infest the hair on your head, as well as the eyebrows and eyelashes. Tiny louse eggs called nits are tightly attached to individual hairs and live close to the scalp, where they may be difficult to see. Lice are easily spread, especially among school-aged children. Lice cannot jump or fly but are spread by direct head-to-head physical contact, sharing clothing such as hats or bedding, and sharing combs or brushes with someone who has head lice. Having head lice does not mean you have poor cleanliness. Head lice do not carry diseases.
Extremely itchy scalp
Small red bumps on the scalp or neck
Tiny white nits on the hair close to the scalp that are difficult to remove
Crawling sensation on the head
Lice are easier to see in bright light and by parting the hair to see close to the scalp. They are also easier to see near the ears and the nape of the neck.
Over-the-counter lotions and shampoos that contain pyrethrin or 1% permethrin are often the first choice. The package directions should be followed exactly. These products may continue to kill lice for 2 weeks after treatment; many clinicians recommend a second treatment 7 to 9 days after the first. Side effects of permethrin may include burning or stinging, itching, red skin, or numbness. Prescription-strength 5% permethrin, malathion lotion, or benzyl alcohol lotion may be needed. Lice are becoming resistant to permethrin, so the other medications may be used.
There is no clear scientific evidence that lice can be suffocated by home remedies such as mayonnaise or olive oil, but they may be suffocated by Cetaphil cleanser. Tea tree oil is another helpful natural remedy.
It is very important that the nits are removed. This can be difficult because they cling tightly to the hair. Special nit combs are available at drugstores. You should do a second combing 7 to 10 days after the first. Nits may live for 2 weeks.
Hats, scarves, coats, and bedding should be washed in hot water and dried in a hot dryer for at least 20 minutes. Combs and brushes should be washed and the room of the infected person should be vacuumed.
Children should be cautioned not to share hats, combs, or brushes with others. Policies regarding school attendance for children with head lice vary.
Sources: National Library of Medicine, Centers for Disease Control and Prevention, American Academy of Dermatology, American Academy of Pediatrics
US National Library of Medicine www.ncbi.nlm.nih.gov /pubmedhealth/PMH0001843/ (accessed February 14, 2013)
Centers for Disease Control and Prevention www.cdc.gov/parasites/lice/
American Academy of Dermatology www.aad.org/skin-conditions/dermatology-a-to-z/head-lice
American Academy of Pediatrics Health Children www.healthychildren.org/English/Pages/default.aspx
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Goodman DM, Burke AE, Livingston EH. Head Lice. JAMA. 2013;309(22):2398. doi:10.1001/jama.2013.4430