Help, head lice! How to get rid of the pesky parasites

Is your head itching? That’s often not a great sign. Especially not for parents – because children scratching their heads isn’t usually a sign of them brooding, but rather an unwelcome guest, namely the head louse, has paid a visit.

Get out the combs, put on the plastic gloves and prepare the lice repellent! Here’s the most important information on head lice and how to get rid of the unwelcome intruders.

Head lice: harmless but annoying parasites

The description of a head louse can make your stomach turn. According to an information sheet from the city of Zurich «head lice live exclusively on the human head and feed on human blood.» Ewww, yuck!

In fact, the head louse is a parasite that is dependent on a specific host: humans. Or, to be more precise, on their head. On around the ninth day of her five-week life, the adult female head louse lays around five eggs every day. They’re about the size of a grain of sand. After ten days at the latest, the larvae hatch and what remains is the nit – an empty eggshell. Everyday the young head louse (called larva or nymph) now sucks blood, until it’s reached its full size of three to four millimetres after nine days.

You can find out what the head louse looks like and in which environment the larva feels particularly comfortable on LausInfo.ch (page in German) – a helpful information platform on the subject.

Head lice are irritating but harmless and can be successfully treated. They’re found all over the world, but don’t transmit any diseases or pathogens in Central Europe.

Transmission: how head lice spread

Another piece of good news: head lice can neither fly nor jump and only come into contact with new hosts through direct head-to-head contact. But their legs, which are equipped with claw-like projections, allow them to climb easily through hair. That’s how they’re able to spread quickly through close social contact. Direct hair contact is particularly common in children who are playing and putting their heads close together, resulting in a rapid spread of lice infestation.

The German Robert Koch Institute adds: «Indirect transmission is also possible in rare cases, via objects that are used together for a short period of time, for example combs, hairbrushes or headgear. Pets aren’t carriers because the head louse lives exclusively on the human scalp.»

By the way: the transmission of head lice isn’t a question of hygiene. Unfortunately, even frequent hair washing won’t protect you from a lice infestation. And no, lice aren’t just a problem for children. Any close physical contact in the family affects all heads.

Do I have head lice? Symptoms of an infestation

The most obvious sign of a lice infestation is an itchy scalp. However, a lice infestation is only confirmed when live head lice are found on the scalp. The main symptom of itching is caused by the stings of the larvae, which (intensified by scratching the scalp) can also cause bacterial superinfections.

These trigger another possible lice symptom: lice eczema. The rash usually appears behind the ears, on the back of the neck or on the back of the head. Local swelling of the lymph nodes may occur, but it may be that they’re no symptoms at all. Then the only thing to do is to look for eggs in your hair, strand by strand, with the naked eye – if you find any, you’re also likely to have a lice infestation.

Help! What now?

If you find live head lice in your children’s hair, the first thing to do is to talk. Although there’s no legally binding obligation to report head lice in Switzerland, transmission can only be contained with speedy communication. In the event of a louse infestation, the guidelines for parents and schools vary greatly from canton to canton. The recommendations are often based on international guidelines on how to control louse infestations for authorities, parents and schools.

For parents this means: if you find lice in your children’s hair, you should inform your immediate environment as soon as possible. This means the school, daycare centre, after-school care, acquaintances, your employer and the neighbours.

Start treatment immediately and keep an eye on the situation for about two weeks afterwards, as new larvae may hatch during this time.

Even if your children have lice, they can still go to class or after-school care. However, it’s advisable to leave long hair tied up until the treatment’s over. There’s no obligation for you to stay at home if you suspect lice.

For schools, a head lice specialist should be informed as soon as a child in the school class has head lice. . They’ll check the whole class for live lice and remove them with a louse comb if necessary.

Treating head lice

If you see live lice on your scalp, it’s important to start treatment immediately. However, if you only find eggs or nits – only trained specialists can tell the difference – you should monitor the situation twice a week for 14 days using a louse comb. If new larvae hatch during this time, you must start treatment.

Treatment is carried out with a head lice remedy, called pediculocides. These vary in their effectiveness, and larvae can also hatch after the first treatment, which is why a second treatment after eight to ten days is strongly recommended. According to the package insert, you leave the product on for between 15 minutes and an hour (depending on the product) and then wash it out thoroughly.

The small parasites can be combed out of wet hair and you can usually buy the necessary louse comb at any pharmacy. In four sessions, carried out on days 1, 5, 9 and 13 after the start of treatment, the freshly washed, wet hair is combed through strand by strand to remove eggs and larvae.

The Robert Koch Institute recommends this procedure, because studies show it led to successful delousing in 57 per cent of affected children. Continue to check the scalp for newly hatched larvae for two weeks after completing the treatment and repeat the treatment as often as necessary.

Watch out for head lice remedies: many fail when tested

The question of which product is most effective against head lice is one that concerns many parents. Basically, there are chemical and physically acting pediculocides. However, according to «Lice Info», chemical louse repellents were discontinued in Switzerland in 2022. Although the insecticides successfully kill head lice and larvae, the toxic treatment poses a health risk. In addition, the body quickly develops resistance to the chemical agent, which isn’t helpful in the case of reccurring lice infestations.

Physically acting pediculocides are less problematic: here, a low-viscosity substance, usually silicone oils, flows into the respiratory system of the head louse and blocks the respiratory opening of the louse eggs. Generally, many lice products on the market promise more than they deliver. Parents report seeing the little crawlers even after (repeated) treatment with lice shampoos. This is why it’s so important to use the head lice remedy on several days. In a 2015 control study (in German) of the 15 best-selling lice remedies, only four manufacturers were able to prove the effectiveness of their product. They’re effective against head lice, are gentle on the scalp and pose no risk of allergies. All manufacturers use physically acting pediculocides and these are readily available on the Swiss market.