What are head lice?

Head lice are tiny, sesame seed-sized, greyish-brown, wingless insects that live on the scalp, feeding on blood. They lay eggs (nits) on hair close to the scalp that may look like dandruff. These nits hatch into baby lice (nymphs) in 9 to 10 days. Nymphs become adult lice in 9 to 12 days. Adult lice can live for up to 30 days on a person’s head. A female louse can lay 5 to 6 eggs per day.

Do head lice cause illness or spread disease?

No, head lice do not cause illness or spread disease. However, they can be irritating because they cause discomfort and spread easily from person to person.

How are head lice spread?

Anyone who has hair can get head lice. Having head lice does not mean a person has poor personal hygiene or lives in an unclean environment.

Head lice are commonly spread among children and adults who have close head-to-head contact. Head lice cannot jump or fly from one person to another. They are most commonly spread through head-to-head contact by crawling from one hair to another. There is a very small chance of head lice spreading indirectly through shared pillowcases, hair accessories, hats, brushes and combs.

How do I prevent the spread of head lice?

The best way to prevent the spread of head lice is to encourage children to avoid head-to-head contact. Teach them not to share hats, combs, hair accessories or hairbrushes. If your child has long hair, tie it up or put it in a braid.

Having head lice once does not prevent someone from getting them again. Regular checks for head lice can be part of a family’s hygiene routine.

What are the symptoms of head lice?

Often people who have head lice will have no symptoms.

Symptoms of head lice may include:

• Crawling or tickling sensation on the scalp
• Itchy scalp due to a sensitive reaction caused by the bites
• Scratch marks or small red bumps like a rash

How can I tell if my child has head lice?

To check for head lice, use the wet combing method:

• Wash and rinse the hair. Apply enough conditioner to cover the whole scalp. The conditioner stops the lice from moving, making them easier to find
• Sit your child under a bright light; a magnifying glass may help you see
• Divide hair into 4 sections and check each section one at a time with a fine-toothed comb. You must check the entire head
• After each stroke, wipe the comb on a paper towel and check for lice

Lice move very fast. Lice are usually found very close to the scalp, at the bottom of the neck and behind the ears.

If your child has an itchy scalp or was exposed to head lice, check their hair right away and look close to the scalp. Check again once a week for 2 weeks in case you missed them. If you only find nits and no lice, check again every day for one week to make sure that you did not miss any live lice.

If someone in the house has lice, check all family members.

What are safe options for treating head lice?

There are many different products and ways to treat head lice. They can all be obtained over the counter. Only consider treatment if you find live lice. Head lice will not go away without treatment.

Children should not be sent home or kept home from school or daycare because of head lice.

If one person in the household has head lice, there is a good chance other household members do as well. All members of the household should be checked on the same day, and those with lice should be treated.

Chemical treatments

Shampoos, creams, rinses and sprays that contain an ingredient that kills lice are available at most pharmacies without a prescription. Some examples are permethrin, pyrethrins, isopropyl myristate and dimethicone.

Some chemical treatments may not be safe for infants, young children, pregnant or nursing people or other individuals. Speak to your health care provider or pharmacist to find out which is best for you or your child. Always carefully follow the directions for use on the label and keep the products out of the reach of young children.

After treatment, check the hair and remove eggs and lice. You can also remove the nits, although you don’t have to remove them, as nits are empty eggshells.

Most treatments are repeated in 7 to 10 days to make sure that any head lice that have hatched after the first treatment are killed before they have a chance to lay any eggs. It is also important to check the head for any eggs and remove them after the second treatment. The itching may last for 7 to 10 days, even after successful treatment.

Head lice have started to develop resistance to many of the chemical products. The product is not working if there are live lice detected after 2 properly applied applications of an approved product 7 to 10 days apart. In this case, consider a full treatment plan using a topical treatment of a different type.

Irritation from chemical products is common and not a sign that the product is not working.

Wet combing is less expensive and non-chemical. Combing treatments follow the same steps used to check for lice. Use generous amounts of hair conditioner and a special lice comb, every 4 days for at least 2 weeks. If you find lice on the final combing, add one more combing in 4 days until you find no live lice.

When should I call my health care provider?

Call your health care provider if the treatments are not successful or if you are unsure which kind of treatment is best for you or your child. Health care providers can advise safe chemical treatment plans for pregnant or nursing people and children less than 4 years of age.

What options are not recommended for treating head lice?

Some methods and products should not be used because they are either not safe or do not work. These products include insect sprays, motor oil, gasoline, alcohol, flea soap, dyes, bleaches, heat applied to the scalp, garlic, mayonnaise, petroleum jelly, olive oil, vinegar, margarine, tea tree and other essential oils, electric lice combs and shaving the head.

What should be cleaned?

Head lice rarely leave the scalp and if they do, they can only survive for 1 to 2 days. Head lice are not spread through contact with furniture, pets or carpets. There is no evidence that a major cleaning of the house or car is necessary. Hats, pillowcases, combs and hairbrushes that have had contact with the head of the person with head lice in the previous 48 hours could be considered for cleaning in hot soapy water, and dry them in a hot dryer for 15 minutes. Items that can not be washed can be placed in an airtight plastic bag for 2 weeks.