Head Lice Information Sheet
Head lice (also referred to as Pediculosis) are tiny insects the size of a pinhead that live only on the human scalp,
where they lay eggs called nits. After the eggs hatch, the empty shells are white. Head lice do not spread disease
or indicate poor personal hygiene and living conditions. They are a nuisance and unpleasant, but they are not
dangerous.
What do head lice look like?
- Lice have 3 stages – the egg (nit), the nymph and the adult.
- Nits are whitish-grey, tan or yellow ovals, about the size of a grain of sand. They stick to the hair close
to the scalp and can look like dandruff. Nits hatch into nymphs in 9 to 10 days. - Nymphs are baby lice. They look like adult lice but smaller.
- Adult lice are hard to see since they are about the size of a sesame seed. Adult lice can live for up to 30
days on a person’s head, but die within 2 days away from the scalp.
How do they spread?
Head lice spread easily by crawling quickly since they do not fly or jump/hop. They are very common among
students in schools and other child care facilities and spread:
- through direct head-to-head contact;
- Indirectly by sharing clothing (hats, scarves, coats, etc.) or articles (combs, brushes, towels, stuffed
animals, headphones) recently worn or used by an infested person; - Lying on a bed, couch, pillow or carpet that has recently been in contact with an infested person;
How do you know you have head lice?
One of the first signs of head lice is an itchy scalp, but it’s possible to have head lice without any symptoms.
Most itchy scalps are not from head lice. If your child has an itchy scalp or was exposed to head lice, check their
hair right away. Check again once a week for 2 weeks in case you missed them.
How do I check for head lice?
Carefully comb through the hair with a fine-toothed comb (or lice comb), scanning the scalp for moving lice and
nits. If you only find nits, your child may not have head lice. Usually, children have no more than 10 to 20 live
lice. The following tips will be helpful when checking for head lice:
- Ensure good lighting and use a magnifying glass, if available.
- Ensure to check the entire scalp especially at the bottom of the neck and behind the ears.
- Check for movement as head lice move very fast and are difficult to spot.
- To look for nits, part hair in small sections, moving from one side of the head to the other. Look close to
the scalp.
How can I treat head lice?
Many pediculicides are available. If someone in the house has lice, check everyone in the household. Do not
treat anyone with a head lice product unless you find live lice in their hair. Consult with a health professional
to find the treatment most suitable. Lice treatment can be over-the-counter or prescription. Ensure you’re
following the product instructions for reapplication, sitting time, rinsing, allergy information, age limitations and
other precautions and/or restrictions (i.e. pregnant or breastfeeding). The first application of lice treatments
won’t kill all of the eggs, so a properly timed second treatment is needed as directed by a health professional or
product instructions. This will kill the newly hatched lice. Do not use hair care products for the duration of any
treatment.
Insecticides
Insecticides are chemicals that kill insects. In Canada, 2 insecticides are approved to treat head lice:
- pyrethrin (found in R&C shampoo + conditioner)
- permethrin (Nix creme rinse or Kwellada-P creme rinse)
Non-insecticides
There are several other non-insecticidal treatments that are available in Canada. These products are usually
more expensive than insecticides. It is not known for sure whether they work better.
How to prevent head lice?
Inform your household of the following tips to prevent exposure to head lice:
- Avoid sharing personal items such as combs, scarves, hairbrushes/combs, hats or hair accessories;
- Avoid lying on furniture that has been recently in contact with an infested person;
- Educate household members of the symptoms, treatment and prevention of head lice;
- Avoid beds, linens and couches that are suspected to have been in contact with lice;
- Wash any exposed linens with hot water and dry on high heat for at least 15 minutes;
- Alternatively, store items in an airtight plastic bag for 2 weeks.
Head lice do not live long off the scalp so additional cleaning beyond the steps mentioned above are not
necessary.
For more information on the treatment and prevention of Pediculosis please visit the Head lice | Caring for kids
Updated on Tuesday, February 11, 2025.