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Head lice are tiny, barely visible insect-like animals (“arthropods”) that may live on the head and cause itching. ("Lice" is plural; the singular is "louse.") Head lice may also live in the eyebrows, eyelashes, and beard. However, sometimes infestations in these areas are from a related species called pubic lice.
Head lice spread by personal contact and by sharing combs, brushes, hats, and other personal items.
A risk factor is something that increases your chance of getting a disease or condition. Risk factors include:
- Age: childhood
- Sharing combs, brushes, hats, and other personal items
- Personal contact with people who may have lice
- Extreme itchiness
- Skin breaks and possible infection (caused by scratching)
- Swollen lymph nodes
- Bacterial infection (if scratching causes open areas on the scalp)
- Some persons with head lice do not have symptoms.
The doctor will ask about your symptoms and medical history. A physical exam will be done. The doctor will examine your head and scalp for lice and lice eggs (called "nits").
Do not self-diagnose and self-treat head lice. Some treatments can cause irritation and should only be used by people who have the infestation.
Treating head lice involves removing eggs and killing lice so that they can't continue to lay eggs. Treatment may be difficult because in some regions lice have become resistant to many of the commonly used medicines. Some experts recommend that treatment be given only when live adult lice are seen.
- Applying over-the-counter shampoo containing the insecticide permethrin. It is very important to use medicines as directed. Retreatment at 7-10 days is usually required to kill any lice that hatch from unremoved eggs.
- Removing lice on the eyelashes, which may be difficult. Tweezers can be used to pick them off. Vaseline may be used to coat the eyelashes and kill the lice.
- Unless instructed otherwise, remove eggs manually with specially designed combs. Eggs stick firmly to hair. Products such as “Clear," which loosen the eggs, may assist in removal.
Most cases of head lice can be treated with over-the-counter preparati