What You Should Know About Head Lice

Also known as pediculus humanus capitis, head lice are parasitic insects found on the head, eyebrows and eyelashes. Lice feed on human blood multiple times per day and live near the scalp.

Lice are not known to spread other diseases, but they can be an annoyance and require prescription treatment to remove. Here’s a look at the types, signs and treatments of head lice.

Types

Head lice come in three forms:

Egg/Nit: This refers to lice eggs laid by the adult female head louse, typically at the base of the hair shaft nearest to the scalp. Nits appear yellow or white, though they can be tough to see in some cases. They’re often confused with dandruff, and empty nits can be tough to distinguish from already-hatched nits.
Nymph: A nymph is an immature louse that hatches from the nit. It looks like an adult head louse, but smaller.
Adult: The fully grown louse is about the size of a sesame seed. It has six legs, and appears tan or grayish white. For people with darker hair, they may look darker. Adult lice feed on blood, and can live for about 30 days if it stays attached to the head—it will die in one or two days if it falls off.

Causes and Risk Groups

It’s estimated that between 6 and 12 million lice infestations occur in the United States each year among children between ages 3 and 11. The condition is most common among children of these ages, particularly those attending child care programs. Possibly due to claw grasping abilities on hair shafts, head lice infestations are much less common among African-Americans in the United States than among people of other races.

Symptoms and Transmission

Symptoms of head lice may not always be noticeable, but when they are, they can include:

Itching: The most common symptom, itching on the scalp, neck and ears is an allergic reaction to louse saliva. Itching may not occur for two to six weeks after a first infestation.
Lice on scalp: Lice are small and move quickly, so they can be tough to spot.
Lice eggs on hair shafts: Lice eggs can also be tough to spot in some cases—and the presence of lice eggs (nits) doesn’t necessarily signal an active infestation.
Irritability and difficulty sleeping: Head lice are most active in the dark.
Sores on the head caused by scratching: These can become infected with bacteria from the skin.

Head lice are able to crawl, but they are not able to jump or fly. Most transmission is due to direct contact with another person. Indirect transmission is far less likely, but it can take place via:

Hats and scarves
Brushes and combs
Hair accessories
Headphones
Pillows
Upholstery
Towels
Items of clothing stored together

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Household pets do not play a role in spreading head lice.

Treatment and Risk Reduction

Treatments for head lice may include:

Over-the-counter (OTC) products: These products often contain pyrethrin, a chemical that is toxic to lice.
Prescription medications: In certain geographic regions, head lice develop a resistance to over-the-counter medications. OTC medications could also fail due to improper use. In these cases, prescriptions such as benzyl alcohol, malathion and lindane might be used. Ask your doctor about any side effects these may have.

Some people find success in combatting head lice through various lifestyle changes and home remedies. Preventing lice is difficult among children in child care facilities and schools, but having them practice proper garment storage can help to a degree. For more information or recommendations on treating head lice, speak to your doctor. ]