Head Lice: Causes and Symptoms

What are head lice?

Lice are tiny insects, 1 to 3 mm long, about the size of a sesame seed, and greyish or tan in colour. They live on the scalp near the hair roots for up to 30 days. They can also live in eyebrows and beards.

Female head lice lay 3 to 8 eggs called nits each day until they die. They attach the nits to hair shafts about 6 mm from the scalp with a cement-like substance. This substance is so strong that the nits cannot be removed by washing the hair. Live nits can be greyish white, yellow, tan, or brown. They look like tiny (less than 1 mm), swollen scales.

After 7 to 10 days, the nits hatch into nymphs. Empty nit shells turn a dull yellow colour and remain attached to the hair. Nymphs become adults 6 to 10 days after hatching and the cycle begins again.

Do head lice live on objects such as pillows?

Lice are parasites that feed exclusively on human blood. Because they need to feed several times a day and require a certain temperature range to survive, lice that fall off a person's head will die within 2 days.

Nits can survive for up to 10 days away from a person's head, but the nymphs that hatch will die within 2 days if they cannot reach a person's head. The risk of these nymphs reaching a human head before they die is very low because nymphs, like lice, do not have wings and cannot jump or fly.

What are the symptoms of a lice infestation?

An itchy scalp is the main symptom. The itchiness is the result of an allergic reaction to the saliva that the lice inject into the scalp when they feed, several times a day.

If the itching is severe, it can interfere with sleep and lead to a lot of scratching, which can cause redness or sores. In rare cases, the sores can become infected.

Not everyone will have symptoms! If a family member has been in close contact with someone who has lice, you should check their scalp even if they don't have symptoms.

How do lice spread?

Lice can move very quickly from one infested person's head to another by direct hair-to-hair contact. Children can easily get lice because they often do activities with their heads close together and hug each other. Because of this, schools and daycare centres are places where lice are often spread.

Adult lice and nymphs can be spread by contact with personal items (e.g., hats, combs, hairbrushes, pillowcases, etc.), but the risk is low because they die within 2 days if not on a human head. As a precaution, items that have been in contact with an infested person's head should be treated to kill any lice or nits.

If you receive a notice from your school or daycare centre asking you to check your child’s head, don't take this lightly. Quick screening and treatment will prevent lice from spreading to family members and other people.

Debunking Lice Myths

• Head lice do not discriminate. They infest people from all walks of life, regardless of personal hygiene.
• Lice do not spread disease and do not cause hair loss.
• Lice cannot be spread by pets because they cannot feed on them.
• Lice do not jump or fly. They require direct head-to-head contact to spread from one person to another.

How to avoid getting lice

There are several things you can do to reduce the risk of getting lice.

• If your child has long hair, keep it tied back or braided.
• Tell your child not to put his or her head against a friend's head when reading, playing or hugging.
• Tell children to put toques, hats and scarves inside the sleeve of their coats in their locker at school.
• Remind children not to share hairbrushes, hair elastics, headbands, toques or hats with their friends.

There are lice prevention sprays on the market that contain various essential oils or insect repellents. However, there is little data on their effectiveness, and some products may irritate the scalp. Ask your pharmacist for professional advice before using them.

When and how to check if your child has head lice

You should check for lice any time your child has been exposed to head lice or complains of an itchy scalp. If you do not see any lice, check again once a week for 2 weeks to make sure you did not miss them, as they crawl very fast and are not easy to see.

It is best to use a special lice comb because its teeth are very close together, allowing it to catch adult lice and nits. Electric lice combs are no more effective and much more expensive. Regular combs have too much space between the teeth to catch nits and most lice.

To check your child's head, make sure you have good lighting. A magnifying glass may also be helpful. Wet the hair before checking as this will slow down the lice and make them easier to spot. You can also use conditioner to make combing easier.

Look for lice and nits everywhere on the scalp, but particularly behind the ears and near the nape of the neck. Start with the nape and ears and divide the hair into sections about the width of the comb. Check the hair one section at a time by running the comb from the scalp to the hair tips. After running through each section, check the comb for nits or lice. Once you finish checking, don’t forget to wash your hands.

It’s easy to confuse nits with dandruff, dead scalp skin, dust or dirt. The difference is that nits cling to the hair, and you sometimes have to remove them with your nails or tweezers.

If you find lice or live nits on your child’s head, you should treat them. If you find only dead nits, no treatment is needed. Because it can be difficult to tell if nits are dead or alive, don’t hesitate to ask a healthcare professional to help you determine if treatment is needed.

How to treat head lice

You should only use a head lice product if you found live nits or lice on the hair of the person. If several family members have lice, treat everyone on the same day.

• Go to the pharmacy to get lice treatment. Several products are available without a prescription. They contain insecticides (permethrin, pyrethrins) or other ingredients (isopropyl myristate/cyclomethicone, silicone oil dimeticone, benzyl alcohol 5%) that have been shown to effectively kill lice.
• Always ask your pharmacist to recommend the best treatment for you or your child, especially if your child is less than 4 years old or if you are pregnant or breastfeeding.
• Read the package insert before you begin treatment. Follow the directions for use carefully.
• Once you've applied the treatment, use a lice comb to remove any nits or lice that you find. Dip the comb in hot water after each stroke. If nits don't comb out, remove them by pulling them down the hair shaft with your nails or tweezers. Taking the time to remove eggs and lice with a lice comb greatly increases the chances that the treatment will work.
• Repeat treatment as directed, usually after 7 to 10 days (check the package insert).
• See your pharmacist again if the treatment doesn’t work.

When treatment doesn’t work

Lice treatment may not work for various reasons:

• You didn’t follow the product instructions:
  • You applied the product to dry instead of damp hair (or vice versa, depending on the product).
  • You didn’t leave the product on the hair long enough.
  • You didn’t reapply the treatment at the right time.
  • You did not follow the instructions on how to wash the person's hair after the treatment.
• The person has been reinfested.
• The lice are resistant to the product. Microbes and parasites can adapt and become resistant to existing treatments. Your pharmacist can recommend a different product.

Home lice remedies

Some people suggest using fatty substances, such as petroleum jelly, mayonnaise, olive oil or margarine, to “suffocate” the lice. Although these products can make it harder for lice to breathe, no study has demonstrated that they actually kill lice.

Certain essential oils (e.g., tea tree, lavender, peppermint, eucalyptus, rosemary, clove) are also marketed to treat head lice, but there is little evidence that they are effective. While these may be seen as a better, natural option, they are not without risk as they can cause skin irritation or an allergic reaction.

If you want to avoid traditional lice products, you could opt for manual lice removal, but this is very time-consuming and you need to be very thorough. Check for lice and nits every 4 days for at least 2 weeks until you find no live lice.

Cleaning personal items

Clean only personal items that came into contact with the hair of the infested person in the previous 2 days, such as caps, hats, combs, hairbrushes, clothing, pillowcases, towels.

• Wash objects with hot soapy water for 5 to 10 minutes.
• Wash clothing, towels or pillowcases in hot water and dry them on high for at least 15 minutes.
• Store items that can't be washed in an airtight container for 2 weeks.

There is no need to for extra cleaning around the house. Insecticide sprays are also strongly discouraged. These products are ineffective for lice infestations and can pose a major health risk for people and animals exposed to these potentially toxic products.

Should I keep my child home?

You do not have to keep your child home from school or daycare because of lice. Lice do not spread diseases. They are a nuisance, but they are not dangerous.

To help stop the infestation quickly, make sure to notify your school or daycare immediately so that other parents can check their children and treat them if necessary. Do not be embarrassed! Head lice are very common in young children and are not a sign of poor hygiene.

Your pharmacist can help you get rid of lice!

For more information on how to treat head lice, don't hesitate to talk to your pharmacist. They will be able to recommend the best treatment for your needs and give you tips on how to make sure it is effective.