Head Lice in Children: Spot Them, Treat Them, Stop Them Coming Back

A week after the start of term, your daughter is scratching behind her ears. You part her hair under the lamp and see tiny whitish dots stuck near the root. Head lice are back at school, and they have found a new home. There is nothing to be ashamed of: they have nothing to do with cleanliness and affect every family.

They do not spread disease. But they itch, they spread quickly among siblings and they readily come back if treatment is done sloppily. Understanding their life cycle is the key to getting rid of them for good.

How does a louse live, and why does it come back?

An adult louse is 2 to 4 mm long, grey to black. The female lays about ten eggs a day, the nits, glued to the base of the hair. According to the American Academy of Pediatrics (AAP), they hatch in 7 to 12 days depending on temperature; the French Society of Dermatology says 8 to 10 days. Young lice become adults in about ten more days, and a louse lives around 28 days.

This cycle explains everything. A treatment kills live lice, but some nits often survive. If you do not repeat it at the right time, they hatch and the story starts again. Hence the golden rule: a first treatment, then a check and often a second pass a week later.

How do they spread?

Mostly through direct head-to-head contact: children playing, cuddling, sharing a cushion at nap time. More rarely, through a borrowed hat, brush, comb, hair clip or helmet. Lice do not jump: they simply crawl from one hair to another. Away from a head, they survive only a few days.

How do I know if my child has lice?

The only certain proof is finding a live louse. Itching is the most common sign, especially behind the ears, on the nape and at the temples, but it can take 4 to 6 weeks to appear, and some children do not scratch at all.

You can tell nits from dandruff or dust with a flick: dandruff comes off easily, a nit stays firmly stuck to the hair, often very close to the scalp, behind the ears or at the nape of the neck.

Which treatments against lice work?

There are two main families of treatments, sold at the pharmacy, in addition to combing.

Countries do not all agree. The UK’s NHS considers permethrin products unlikely to work, because of resistance. Quebec public health, on the other hand, still ranks it first choice. In practice, ask your pharmacist for advice, tell them if a treatment has already failed, and choose a different type of product if it does.

The quantity, leave-on time and number of applications are those on the leaflet: follow it to the letter. Most products are repeated 7 to 10 days after the first pass, to reach the lice that came out of the nits. Check the head two days after treatment: if you still find live, active lice, change product.

A few safety rules, recalled by the AAP: an adult applies the product, the child is never left alone with it, you rinse over a basin with lukewarm water rather than in the shower, and you never cover the head with a plastic bag. Bottles are stored out of reach, with the other medicines in your medicine cabinet.

Methods to avoid, even if people recommend them

Lice sometimes push people towards extreme solutions. Some are dangerous:

• petrol, gasoline or kerosene: toxic and flammable, never to be put on a head;
• household insecticides and room sprays: useless, and they expose the whole family to chemicals;
• veterinary products (flea treatments for dogs or cats);
• essential oils: the SFD advises against them in children and pregnant women;
• mayonnaise, olive oil, petroleum jelly: the AAP stresses that no evidence shows they work.

The NHS adds “repellent” sprays and electric combs to the list, judged ineffective. And there is no need to shave a boy’s head or cut a girl’s hair.

If an anti-lice product is swallowed or gets in the eyes by accident, call the Poison Control Centre (0801 000 180, free number) or 141.

Laundry, brushes, home: what really needs washing?

Much less than people think. Lice do not live long away from a head. Focus on what touched your child’s head in the previous two days:

• pillowcases, hats, scarves, towels: machine wash at 50 °C at least;
• what cannot be washed (soft toy, helmet, cushion): sealed in a closed plastic bag for about ten days;
• brushes, combs, hair clips: soaked in very hot water or washed thoroughly.

The NHS even considers that a high-temperature wash is not essential. No source recommends disinfecting rugs, sofas or the car with insecticide. Instead, teach each child to keep their own brush, a useful habit all year round; small ones suited to the youngest are available in the hairbrushes section.

Check the heads of everyone in the house on the same day, including parents and the grandmother who does the little girls’ hair, and treat only those who have live lice.

Lice at school: should my child stay home?

Recommendations differ. In the UK and the US, exclusion is not on the table: the AAP and the US national association of school nurses even oppose “no-nit” rules. In Quebec, public health asks that the child has had a first treatment before returning to school or daycare, but remaining nits do not justify exclusion.

In Morocco, each nursery and school sets its own rule: ask the head. In every case, tell the teacher or carer. It allows other parents to check their children’s heads at the same time, which avoids the ping-pong of reinfection. To prepare for the start of term and its outbreaks, see also our article on starting nursery or preschool and the one on nursery illnesses.

As with intestinal worms, the secret against lice comes down to a few things: a treatment followed properly, regularity, and the whole family moving together.