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Iowa Department of Health and Human Services

Head Lice

What do head lice look like?

Adult lice are the size of a sesame seed (2-3mm) and can be seen by the human eye. They live in human hair, draw blood from the skin, and lay eggs (called nits) on the hair shaft. Live nits are found close to the scalp and most often on hair at the back of the head in the neck region. Some children with lice complain of itchiness but many have no symptoms. 

Is your child at risk?

Yes. Head lice will spread as long as children play together. They spread almost completely through human hair-to-hair contact, and pets do not spread lice. Anyone can get head lice. Children in child care, preschools, elementary, or middle schools are at risk. Head lice are NOT a sign of being dirty. Head lice are not dangerous and DOES NOT spread diseases.

Do head lice spread in swimming pools?

Data show that head lice can survive under water for several hours but are unlikely to be spread by the water in a swimming pool.  Head lice have been seen to hold tightly to human hair and not let go under water.  Chlorine levels found in pool water do not kill head lice. 

Head lice may be spread by sharing towels or other items that have been in contact with an infested person's hair, although such spread is uncommon.  Children should be taught not to share towels, hair brushes, and similar items either at poolside or in the changing room. 

Swimming or washing the hair within 1-2 days after treatment with some head lice medicines might make some treatments less effective. Talk to your health care provider if you have questions. 

What can you do?

Parents are the key to looking for and treating head lice! The Iowa Department of Public Health advises parents to spend 15 minutes each week on each child carefully looking for head lice or nits. Persons with nits close to the scalp or live lice should be treated. Careful use of a nit comb can potentially remove all lice. Each child should have his or her own comb or brush. Teach your child NOT to share hats, scarves, brushes, combs, and hair fasteners.

Treatment Options

Never initiate treatment unless there is a clear diagnosis of a head lice infestation. Always read and follow product instructions to their fullest. 


Brand Name

Recommended Age Range

Re-treatment Interval
(if needed)

lotion (1%)


>2 mo

9-10 days

+ piperonyl

Example: Rid

>24 mo

9-10 days



>2 yr

7-9 days if live lice are
seen after initial dose



>6 mo

7 days if live lice are
seen after initial dose



>6 mo

Single use



>6 mo

Single use



Any age if weight >15kg

9-10 days



















Reasons Treatment Did Not Work

  1. Wrong diagnosis – dandruff, hair products, dust, and other objects can seem like nits (the white eggs) and other insects can look like lice.
  2. Poor treatment – directions on the treatment product were not correctly followed.
  3. Resistance to treatment – some lice are not killed by the chemicals in the over-the-counter treatments (permethrin and pyrethrin).
  4. Timing – the lice may take a few days to die; nits alone do not mean the child still has lice, look for crawling lice.
  5. New lice – child got head lice again from playmate or family member.

If after 8-12 hours of treatment, no dead lice are found and lice seem as active as before, the medicine may not be working. Do not re-treat until speaking with your healthcare provider; a different treatment may be necessary.

What about school?

Students diagnosed with live head lice do not need to be sent home early from school; they can go home at the end of the day.

Students should start treatment as soon as possible but should not be excluded from attending school.

Head Lice Brochure

Order the free "Getting Rid of Head Lice" brochures

View the brochure / Spanish version

Additional Resources

Head Lice (CDC)

Iowa HHS head lice fact sheets