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Head Lice

What are head lice?

Adult head lice, the size of a sesame seed, are tiny, six-legged, grey bugs.  They cannot jump, hop or fly, but do crawl fast.  They live in human hair and bite the scalp to feed on blood.  Lice will usually cause a person’s head to itch and could cause a rash.  Head lice do not carry or spread disease.   

Lice lay their eggs (nits) in human hair.  The eggs (oval and yellow to white) attach themselves to the hair shaft (within ¼ inch of the scalp) and look similar to dandruff but cannot be shaken off.  After about 1 week, the eggs will normally hatch into lice.

Nymphs are baby louse.  They are similar to adult louse, but smaller. 

Who gets head lice?

Anyone can get lice despite good health habits or frequent hair washing.  Head lice are common among children age 3-10 years old and their families.  Dogs, cats and other pets do not get or transmit lice.     

How do head lice spread?

Head lice in children attending childcare or school is common in the United States.  Head lice spread quickly from direct head-to-head contact with a person who has lice.  Lice can also spread when a person uses items such as a comb, brush, pillow, hat or scarf of a person who has lice. 

How long can lice live away from the body?

Head lice cannot live for more than 24-48 hours off the body without a blood meal. 

Where are head lice commonly found?

Head lice are commonly found on the scalp, behind the ears and at the back of the neck.

What are the signs and symptoms of head lice?

Typically, a person may feel a funny sensation of something moving in their hair.  Usually the scalp becomes extremely itchy due to an allergic reaction to the bite. 

How can I stop lice?

There are several anti-lice shampoos and rinses commonly used to treat lice.  If you are not sure what head lice treatment to use, ask your pharmacist or health care provider.  Some require a doctor’s prescription and others are available over the counter. 

Anti-lice shampoo

Follow the package directions and do not use more than directed.  These treatments kill lice but may not kill all nits (lice eggs); therefore, follow up treatment may be needed 7-10 days later.   

Ideas to help remove nits

Removing nits can be a long process.  After using the anti-lice treatment, remove nits using a fine tooth comb or pull out nits individually using your fingernails.  Continue to check every few days for 2 weeks and remove nits with a fine tooth comb until gone. 

Cleaning the home

It is important to vacuum carpets, rugs, furniture and car seats.  Throw out vacuum bags when done.  All clothes, bedding and other items in contact with the infested person within the past 48 hours should be washed in hot water and then placed in the dryer on a hot cycle.  Items, including stuffed animals, that are not placed into the laundry should be vacuumed and sealed in plastic bags for 10 days. Combs and brushes used by a person with lice should be soaked in anti-lice shampoo or hot water (above 130 ° F). 


Check everyone’s head in the home for lice.  If lice or nits are visible, begin treatment with anti-lice shampoo.  If in doubt, have the person checked by a health care provider.  Tell others so that they can also be treated if head lice are found.  Remind your child not to share combs and hats.

Boston Public Health Commission
1010 Massachusetts Ave, 6th Floor, Boston, MA 02118.
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