Lice - FAQ's

Question: What are head lice?

Answer:  Also called Pediculus humanus capitis (peh-DICK-you-lus HUE-man-us CAP-ih-TUS), head lice are parasitic insects found on the heads of people. Having head lice is very common. However, there are no reliable data on how many people get head lice in the United States each year.

Question: Who is at risk for getting head lice?

Answer:  Anyone who comes in close contact with someone who already has head lice, contaminated clothing, and other belongings. Preschool and elementary-age children, 3-10, and their families
are infested most often. Girls get head lice more often than boys, women more than men. In the United States, African-Americans rarely get head lice.

Question:  What do head lice look like?

Answer: There are three forms of lice: the nit, the nymph, and the adult.

Nit: Nits are head lice eggs. They are hard to see and are often confused for dandruff or hair spray droplets. Nits are found firmly attached to the hair shaft. They are oval and usually yellow
to white. Nits take about 1 week to hatch. 

Nymph: The nit hatches into a baby louse called a nymph. It looks like an adult head louse, but is smaller. Nymphs mature into adults about 7 days after hatching. To live, the nymph must
feed on blood. 

Adult: The adult louse is about the size of a sesame seed, has six legs, and is tan to greyish-white. In persons with dark hair, the adult louse will look darker. Females lay nits; they are usually
larger than males. Adult lice can live up to 30 days on a person's head. To live, adult lice need to feed on blood. If the louse falls off a person, it dies within 2 days.

For pictures of what lice look like, click here.. Lice Pictures

Question:  Where are head lice most commonly found?

Answer:  On the scalp behind the ears and near the neckline at the back of the neck. Head lice hold on to hair with hook-like claws found at the end of each of their six legs. Head lice are rarely found on
the body, eyelashes, or eyebrows. 

Question: What are the signs and symptoms of head lice   infestation?

Answer:  Tickling feeling of something moving in the hair. Itching, caused by the an allergic reaction to the bites. Irritability. Sores on the head caused by scratching. These sores can sometimes become infected. 

Question: How did my child get head lice?

Answer:  By contact with an already infested person. Contact is common during play at school and at home (slumber parties, sports activities, at camp, on a playground).

  • By wearing infested clothing, such as hats, scarves, coats, sports uniforms, or hair ribbons.
  • By using infested combs, brushes, or towels.
  • By lying on a bed, couch, pillow, carpet, or stuffed animal that has recently been in contact with an infested person.

Question:  How is head lice infestation diagnosed?

Answer:  By looking closely through the hair and scalp for nits, nymphs, or adults. Finding a nymph or adult may be difficult; there are usually few of them and they can move quickly from searching fingers. If crawling lice are not seen, finding nits within a 1/4 inch of the scalp confirms that a person is infested and should be treated. If you only find nits more than 1/4 inch from the scalp, the infestation is probably an old one and does not need to be treated. If you are not sure if a person has head lice, the diagnosis should be made by a health care provider, school nurse, or a professional from the local health department or agricultural extension service. 

Question:  I have heard that head lice medications do not work, or that head lice are resistant to medication. Is this true?

Answer:  A recent study done by Harvard University did show that SOME, but NOT ALL (or even most) head lice are resistant to common prescription and over-the-counter medications (OTC). There is no information on how widespread resistance may be in the United States. Resistance (medication not working) is more likely in people who have been treated many times for head lice. There are many reasons why medications may seem not to work. Below are some of those reasons: 

  1. Misdiagnosis of a head lice infestation. A person has head lice if they have crawling bugs on their head or many lice eggs (also called nits) within a quarter inch (approximately the width of your pinky finger) of the scalp. Nits found on the hair shaft further than 1/4 inch from the scalp have already hatched out. Treatment is not recommended for people who only have nits further than one-quarter inch away from the scalp.
  2. Not following treatment instructions fully. See instructions below for how to treat a head lice infestation. Using medication alone is not likely to cure a head lice infestation. 
  3. Medication not working at all (resistance). If head lice medication does not kill any crawling bugs, then resistance is likely. If the medication kills some of the bugs, then resistance to medication is probably not the reason for treatment failure (see item #2 and #4).
  4. Medication kills crawling bugs, but is not able to penetrate the nits. It is very difficult for head lice medication to penetrate the nit shell. Medication may effectively kill crawling bugs, but may not treat the nits. This is why follow-up treatment is recommended. See instructions below for a detailed summary.
  5. New infection. You can get infested more than once with head lice. Teach family members how to prevent re-infection. 

Question:  How can I treat a head lice infestation?

Answer: By treating the infested person, any other infested family members, and by cleaning clothing and bedding. 

Step 1: Treat the infested person/any infested family members

Requires using an OTC or prescription medication. Follow these treatment steps:

  1. Before applying treatment, remove all clothing from the waist up.
  2. Apply lice medicine, also called pediculicide (peh-DICK-you-luh-side), according to label instructions. If your child has extra long hair, you may need to use a second bottle.

    WARNING: Do not use a creme rinse or combination shampoo/conditioner before using lice medicine. Do not re-wash hair for 1-2 days after treatment.
  3. Have the infested person put on clean clothing after treatment.
  4. If some live lice are still found 8-12 hours after treatment, but are moving more slowly than before, do not retreat. Comb dead and remaining live lice out of the hair. The medicine sometimes takes longer to kill the lice.
  5. If no dead lice are found 8-12 hours after treatment and lice seem as active as before, the medicine may not be working. See your health care provider for a different medication and follow their treatment instructions.
  6. A nit comb should be used to remove nits and lice from the hair shaft. Many flea combs made for cats and dogs are also effective. Finer-toothed nit combs, available through Wal-Med* and the National Pediculosis Association*, may also be helpful.
  7. After treatment, check hair every 2-3 days and use a nit comb to remove any nits or lice you see. 
  8. Retreat in 7-10 days. 
  9. Check all treated persons for 2-3 weeks after you think that all lice and nits are gone. 

Step 2: Treat the household

  1. To kill lice and nits, machine wash all washable clothing and bed linens that the infested person touched during the 2 days before treatment. Use the hot water cycle (130o F) to wash clothes. Dry laundry using the hot cycle for at least 20 minutes
  2. Dry clean clothing that is not washable, (coats, hats, scarves, etc.) OR 
  3. Store all clothing, stuffed animals, comforters, etc., that cannot be washed or dry cleaned into a plastic bag and seal for 2 weeks.
  4. Soak combs and brushes for 1 hour in rubbing alcohol, Lysol*, or wash with soap and hot (130o F) water. 
  5. Vacuum the floor and furniture. Do not use fumigant sprays; they can be toxic if inhaled.

Question:  My child has head lice. I don't. Should I treat myself to prevent being infested?

Answer:  No, although anyone living with an infested person can get head lice. Have another person check the back and sides of your head for lice and nits. Check family members for lice and nits every
2-3 days. Treat only if crawling lice or nits are found within a 1/4 inch of the scalp.

Question:  Is there a product I can use to prevent getting head lice? 

Answer:  No.

Question:  Should my pets be treated for head lice?

Answer:  No. Head lice do not live on pets.

Question:  My child is under 2 years old and has been diagnosed with head lice. Can I treat him or her with prescription or OTC drugs?

Answer:  No. For children under 2 years old, remove crawling bugs and nits by hand. If the problem persists, consult your pediatrician.


Question:  What OTC medications are available to treat
head lice?

Answer:  Many head lice medications are available at your local drug store. Each OTC product contains one of the following active ingredients.

  1. Pyrethrins (pie-WREATH-rins): often combined with piperonyl butoxide (pie-PER-a-nil beu-TOX-side): 
    Brand name products: A-200*, Pronto*, R&C*, Rid*, Triple X* Pyrethrins are natural extracts from the chrysanthemum flower. Though safe and effective, pyrethrins only kill crawling lice, not unhatched nits. A second treatment is recommended in 7- 10 days to kill any newly hatched lice. Sometimes the treatment does not work.
  2. Permethrin (per-meth-rin):
    Brand name product: Nix*
    Permethrins are similar to natural pyrethrins. Permethrins are safe and effective and may continue to kill newly hatched eggs for several days after treatment. A second treatment may be necessary in 7-10 days to kill any newly hatched lice. Sometimes the treatment does not work.

    Note: If OTC permethrin (1%) does not effectively kill crawling bugs, prescription- strength (5%) permethrin will not be any more effective. If lice are resistant to 1%, they will also be resistant to 5% permethrin.

Question:  What are the prescription drugs used to treat head lice? 

Answer: Malathion (Ovide *): Malathion has just been reapproved for the treatment of head lice infestations. When used as directed, malathion is very effective in treating lice and nits. Few side-effects have been reported. Malathion may sting if applied to open sores on the scalp caused by scratching. Therefore, do not use if excessive scratching has caused a large number of open sores on the head.

Lindane (Kwell*): Lindane is one of the most common treatments used to treat head lice. When used as directed, the drug is usually safe. Overuse, misuse, or accidentally swallowing of Lindane can be toxic to the brain and nervous system. Lindane should not be used if excessive scratching has caused open sores on the head. 

Question:  Which head lice medicine is best for me?

Answer:  If you aren't sure, ask your pharmacist or health care provider. When using medicine, always follow the instructions.

When treating head lice

  1. Do not use extra amounts of the lice medication unless instructed. Drugs are insecticides and can be dangerous when misused or overused.  
  2. Do not treat the infested person more than 3 times with the same medication if it does not seem to work. See your health care provider for alternative medication.
  3. Do not mix head lice medications.

Question:  Should household sprays be used to kill adult lice?

Answer: No. Spraying the house is NOT recommended. Fumigants and room sprays can be toxic if inhaled.

Question:  Should I have a pest control company spray my house?

Answer:  No. Vacuuming floors and furniture is enough to treat the household.

Reference Source:

Question:  Should schools have a "No-Nit" Policy?

Answer:  American Academy of Pediatrics (AAP) attempts to clarify diagnosis and treatment of head lice and makes recommendations for dealing with this condition in school. Among its recommendations, the AAP says no healthy child should be excluded from, or allowed to miss school because of head lice, and that "no nit" policies for return to school should be discouraged. Numerous anecdotal reports exist of children missing weeks of school and even being forced to repeat a grade because of head lice. Although not painful or a serious health hazard, head lice are the cause of much embarrassment and misunderstanding, many unnecessary days lost from school and work, and millions of dollars spent on remedies. The AAP recommendations for treating head lice also include:

  • School personnel responsible for detecting head lice should be appropriately trained, as it can be difficult to diagnose.
  • Permethrin 1 percent (an insecticide) is currently the recommended treatment for head lice.
  • Head lice screening programs in schools do not have a significant effect on the incidence of head lice, and are not cost-effective. Parent education programs may be a more appropriate management tool.
  • Manually removing nits after medication for killing lice is not necessary to prevent spread. However it may be prudent to remove nits in school-aged children to decrease the chance of misdiagnosis. Nit removal is tedious and often cannot be accomplished in one sitting.