Like the common cold, head lice, also known as Pediculosis capitas, are extremely common among school-aged children. Head lice are parasites that feed on human blood; they spread from person to person through physical contact. Anywhere from 6 to 12 million children are affected by the sesame seed-sized insects each year,  though people of any age can get head lice, according to the Centers for Disease Control and Prevention.


The most frequent complaint of head lice is an itchy scalp, although some children may be asymptomatic at first. In fact, it may take more than a month for an individual affected by lice for the first time to notice, the CDC said.

The itching is actually an allergic reaction to lice saliva that enters the bloodstream when lice bite the scalp. Scratching may cause small red bumps on the scalp, neck and shoulders. Intense scratching can lead to a bacterial infection.

People with lice may experience a tickling sensation in the hair, irritability and sleeplessness.

Diagnosis & Tests

The only way to confirm an active lice “infestation” is to find a live louse, the adult form of head lice. This can be done by carefully combing wet hair. Often adult lice can be found behind the ears and on the back of the neck. They live for about a month and can lay dozens of eggs called nits.

Nits are yellow-white in color and can be found attached to hair strands, according to The National Pediculosis Association,. They resemble dandruff but are more securely attached to hair. Viable nits are closer to the scalp. Nits hatch within a week, and within two weeks they are able to lay eggs themselves.

Treatments & Medications

There are both over-the-counter and prescription options to treat lice. Over-the-counter remedies often suffice; however, the directions for use should be followed very carefully. Rid and Nix are examples of shampoo treatments that can be purchased at the drugstore. Rid contains a chemical called pyrethrin and Nix contains permethrin. In some areas of the country, lice have grown resistant to these treatments.

Prescription medications include malathion, lindane and benzyl alcohol lotion. These are extremely potent treatments that can have serious side effects if misused.

Malathion is rubbed into the hair and scalp but can be hazardous for use by pregnant women. Lindane is available as a cream or a shampoo, but a physician may not prescribe it to individuals who weigh under 110 pounds (49.9 kilograms) and pregnant women because it can cause seizures, according to the Mayo Clinic. Benzyl alcohol lotion is not recommended for infants as it can cause deadly side effects.

Because of the chemicals used in head lice treatments, experts caution against using multiple treatments at once. Also, the medication should not be applied more than three times if it has not been successful in treating head lice.

As an alternative to using medication — especially for children up to two years old — a fine-toothed comb can be run through wet hair to remove nits. This should be repeated every few days for about 14 days.

Preventing the spread

It's very hard to completely prevent the spread of lice, especially in children who frequently come in to contact with each other while playing. Once a case of head lice is confirmed, the best way to prevent spread is to thoroughly treat and get rid of the head lice. Avoiding head-to-head contact as much as possible, however, will go a long way in curbing an infestation.

Although a less frequent cause of spread, lice can travel from one person to another via shared clothing and accessories, such as hats, brushes and hair accessories. Individuals can also get lice from linens, carpet and upholstered furniture.

Lice can survive for about 48 hours and nits can survive for seven days off of the human body. Therefore, uninfected people should avoid sharing items, as well as areas recently occupied by someone affected by head lice until everything has been cleaned.

Linens, clothing and stuffed toys should be washed in very hot water. After washing and drying, the Mayo Clinic recommends sealing everything in plastic bags for several days to kill any surviving lice and nits. Finally, vacuum carpeted floors and clean furniture.