Also called Pediculus humanus capitis, head lice are parasitic insects that can be found on the head, eyebrows, and eyelashes of people.
Head lice feed on human blood several time a day and live close to the human scalp. Head lice are not known to spread disease.
Symptoms of head lice infestation may include
- Tickling feeling of something moving in the hair.
- Itching, caused by an allergic reaction to the bites.
- Sores on the head caused by scratching. These sores can sometimes become infected.
Contact with an already infested person is the most common way to get head lice. Head-to-head contact is common
during play at school, at home, and elsewhere (sports activities, playground, slumber parties, camp).
Uncommonly, head lice may be spread by sharing clothing or belongings onto which lice or nits may have crawled or fallen.
Many head lice medications are available at your local drug store. They contain one of the following active ingredients.
- Pyrethrins combined with piperonyl butoxide. Pyrethrins are naturally occurring pyrethroid extracts from the chrysanthemum flower.
Pyrethrins are safe and effective when used as directed. Pyrethrins can only kill live lice, not unhatched eggs (nits).
A second treatment is recommended in 9-10 days to kill any newly hatched lice before they can produce new eggs.
Treatment failures can be common depending on whether lice are resistant to pyrethrins in the patient’s geographic location.
Pyrethrins generally should not be used by persons who are allergic to chrysanthemums or ragweed.
- Permethrin lotion 1%. Permethrin is a synthetic pyrethroid similar to naturally occurring pyrethrins.
Permethrin lotion 1% is approved by the FDA for the treatment of head lice. Permethrin is safe and effective when used as directed.
Permethrin kills live lice but not unhatched eggs. Permethrin may continue to kill newly hatched lice for several days after treatment.
A second treatment often is necessary in 9-10 days to kill any newly hatched lice before they can produce new eggs.
Treatment failures can be common depending whether lice are resistant to permethrin in the patient’s geographic location. Permethrin is not approved for use in children less than 2 years old.
The following is a list of prescription drugs:
- Malathion lotion 0.5%. Malathion is an organophosphate. Malathion lotion 0.5% is approved by the FDA for the treatment of head lice.
The formulation of malathion approved in the United States for the treatment of head lice is a lotion that is safe and effective when used as directed.
Malathion is pediculicidal (kills live lice) and partially ovicidal (kills some lice eggs). A second treatment is recommended if live lice still are present 7-9 days after treatment.
Malathion is intended for use on persons 6 years of age and older. Malathion can be irritating to the skin and scalp; contact with the eyes should be avoided.
Malathion lotion is flammable; do not smoke or use electrical heat sources, including hair dryers, curlers, and curling or flat irons, when applying malathion lotion and while the hair is wet.
- Lindane shampoo 1%. Lindane is an organochloride. Although lindane shampoo 1% is approved by the FDA for the treatment of head lice,
it is not recommended as a first-line therapy. Overuse, misuse, or accidentally swallowing lindane can be toxic to the brain and other parts of the nervous system;
its use should be restricted to patients who have failed treatment with or cannot tolerate other medications that pose less risk.
Lindane should not be used to treat premature infants, persons with a seizure disorder, women who are pregnant or breast-feeding,
persons who have very irritated skin or sores where the lindane will be applied, infants, children, the elderly, and persons who weigh less than 110 pounds.
Centers for Disease Control and Prevention, USA.