What are head lice?
Head lice are tiny, flat insects that live and breed on the head. They lay eggs called nits, which stick to hair very close to the scalp. Head lice are very common and spread easily among young children, especially in child care centres and schools. They can be hard to get rid of.
Lice have three stages: the egg (nit), the nymph (baby) and the adult.
- Nits are greyish-white, tan or yellow ovals approximately the size of a grain of sand. They stick to the hair close to the scalp. They hatch in about 10 days. Once they hatch their remaining shell looks white or clear and stays firmly attached to the hair shaft.
- Nymphs are baby lice. They look like adults but are much smaller. Nymphs grow into adult lice over about two weeks.
- Adults are tan to brown in colour and about the size of a sesame seed.
Nymphs and adults feed on blood from the scalp several times a day.
What are the symptoms of head lice?
One sign of head lice is an itchy scalp and scratching the head. Itchiness might not start right away, however, and depends on how sensitive the scalp is to head lice. It can sometimes take weeks for people with lice to start scratching. Some people might have the sensation that there is something crawling around in their hair.
You might be able to see lice or nits by parting the hair into small sections and checking behind the ears, around the back of the neck and on the scalp. A magnifying glass may help. It is tough to find a nymph or adult because there aren’t many of them and they move very fast.
Scratching the scalp can cause red bumps and sores to develop, which can lead to infection.
You should see a health care provider if the condition seems to be causing more serious symptoms.
How are head lice spread?
Head lice spread through head-to-head contact among children or indirectly on items such as hats, combs, hairbrushes and headphones. They do not fly, hop or jump, but they can crawl very quickly.
Pets cannot catch head lice and pass them on to you, and you cannot pass head lice to your pet.
Head lice can live up to three days off the scalp. Although the eggs can also survive for up to three days, they need a warm environment to develop. They are not likely to hatch at room temperature.
How are head lice treated?
In Canada, three insecticides (substances that kill the lice) are approved for use in treating head lice. Do not treat anyone with a head lice product unless you find lice in their hair.
- Pyrethrin (found in R+C® shampoo/conditioner)
- Permethrin (Nix® or Kwellada-P®)
- Lindane (Hexit® or PMS-Lindane shampoo)
- Pyrethin and permethrin are safe for humans. Lindane, however, can be toxic. Products with lindane should not be used on infants or young children less than two years old.
- You do not need a prescription for these products. Follow package directions carefully.
- Don’t leave the shampoo or rinse in the hair longer than directed on the package.
- It’s best to rinse the hair with cool water over a sink, instead of in the bath or shower, after the treatment.
- Repeat the treatment after 7 to 10 days.
- Sometimes the treatments will make the scalp itchy. If your child is scratching after treatment, it does not necessarily mean the lice are back. Check their head carefully for live lice before assuming they are back.
- A non-insecticidal product called isopropyl myristate/cyclomethicone (Resultz®) has also been approved in Canada, but it should only be used on children four years of age and older.
- this product dehydrates the lice, killing them
- repeat after one week
- Some people use home remedies like mayonnaise, petroleum jelly, olive oil or margarine. These products may make it hard for lice to breathe, but will probably not kill them.
- There is no evidence that products like tea tree oil or aromatherapy are effective in treating head lice.
- Never use gasoline or kerosene. These products can be extremely dangerous.
To get rid of lice or nits from items like hats or pillowcases:
- wash them in hot water and dry in a hot dryer for 15 minutes
- store the items in an airtight plastic bag for two weeks
Since head lice do not live long off the scalp, and since the eggs are not likely to hatch at room temperature, you do not need to do excessive cleaning.
How are head lice prevented?
Avoid head-to-head contact with others until lice are gone. Don’t share personal items like combs, brushes or hair accessories.
Schools and child care centres should let families know when there is a case of head lice and provide information about diagnosis and treatment.
Check family members (adults and children) if someone in the house has head lice.