Head Lice

Head Lice


Intense Itching is a Sign

Head lice are spread by direct contact, such as sharing of combs or hats. They are common in children under the age of 12. Intense itching, especially around the ears and the back of the head, is caused by the lice feeding on blood from the scalp and is a sign of infestation. To ensure that reinfestation does not occur, it is important to remove all dead nits after treatment.

Head lice are usually grayish white and only 4 mm long. They feed on blood from the scalp and cause intense itching.

Head Lice Are Spread by Direct Contact

Head lice (Pediculus humanus capitis) commonly occur wherever children gather. They are spread by direct contact or sharing of such objects as combs and hats. Lice are usually detected after the child complains of intense itching around the ears and the back of the neck where lice feed on blood from the scalp. Lice eggs (nits) can be seen under natural light or with the help of a magnifying glass and are found at the base of the hair shaft close to the scalp. The nits may look like dandruff but will not flake off because they are “cemented” to the hair shaft.

Treatment: Treatment of lice infestation is done in two steps. The first step is to kill the lice and nits with a pesticide in a lotion, gel, shampoo or creme rinse product. These products are safe and effective when used as directed. The products include:

Permethrin (Nix Creme Rinse). This is available without a prescription and is applied to freshly shampooed hair and left on for 10 minutes, then rinsed out. It protects against lice for 14 days, so a second treatment may not be required.

Pyrethrin (A-200, Lice Enz, Pronto, Pyrinyl, R&C, RID and Tisit are some brands) is also available without a prescription. These products are worked into the hair and left for 10 minutes before rinsing thoroughly. Treatment may be repeated in 7-10 days if all nits are not killed.

Malathion (Ovide Lotion). This is a prescription product. It is applied to a dry scalp and allowed to remain for 8 to 12 hours before it is washed away. Treatment may be repeated in 7-9 days if lice remain.

Lindane (Kwell). This treatment also requires a prescription. It is available in a shampoo or lotion and often requires a second treatment in 7-10 days.

The second step in treatment is to remove all dead nits. The nits can be picked off the hair, combed out with a very fine metal or plastic comb or by cutting the hair below the attached nit. One product contains formic acid and is available as a creme rinse (Step 2). It dissolves the cement that holds the nits to the hair shaft.

Cautions: All pesticides used to treat lice require careful and proper use for safe and effective treatment. They may be irritating to the eyes, mucous membranes and scalp. Permethrin and pyrethrin should not be used by patients allergic to chrysanthemums, ragweed or petroleum because severe allergic reactions may occur.

To prevent reinfestation, all members of the family should be checked for lice. Household pets do not carry lice. All bedding and clothing must be machine-washed in very hot water and dried in a clothes dryer for at least 20 minutes. Wash all hair brushes, combs and toys in hot soapy water for at least 10 minutes. Your pharmacist will be able to answer any questions you may have about the treatment of head lice.

US Pharmacist