Head lice are parasitic insects called Pediculus humanus capitis. They only live on the heads of people. They lay eggs, called nits, which stick to hair very close to the scalp. Head lice do not spread disease. Lice present on other body parts covered by hair are not head lice but are either pubic lice (Pthirus pubis) or body lice (Pediculus humanus humanus). Head lice spread through direct contact among children or indirectly on items such as hats, combs, hairbrushes and head phones. Head lice can live up to 3 days off the scalp. Although the eggs can also survive for up to 3 days, they need a warm environment to develop. Head lice infestations occur most frequently in schoolchildren because they tend to be in close personal contact with each other and to share brushes and combs.

Head lice are not associated with a lack of cleanliness (in fact, some believe that lice prefer clean hair). Head lice develop in three forms: nits, nymphs, and adults. Nits are head lice eggs. They are hard to see and are often mistaken for dandruff or droplets of hairspray. Nits are found firmly attached to the hair shaft. Nymphs are immature adult head lice. Nymphs mature into adults about 7 days after hatching. To live, nymphs must feed on blood. An adult louse is about the size of a sesame seed, has six legs, and is tan to greyish- white. In persons with dark hair, adult lice will look darker. Adult lice can live up to 30 days on a person's head. The most common symptom is itching of the scalp, caused when the louse bites through the skin to feed on blood.

Other symptoms include irritation caused by the louse's saliva, insomnia, adenopathy, hair loss in massive infestations and psychological disturbs, also excessive scratching may cause bleeding of the scalp, which may increase the risk of microbial infection. The most important step in treating head lice is to treat the person and other family members with medicine to kill the lice. Cutting the hair very short will cause an insufficient ambient temperature for lice to live in. While effective. Apply conditioner or olive oil to make it easier to comb the hair with the fine-toothed comb. Herbal treatments (including tea tree oil) are sometimes used to treat head lice. Apply lice medicine, also called pediculicide , according to label instructions. You can also add tee tree oil or lavender oil to your regular shampoo.