Written by Dr. Kate McCann
13th June 2024

This morning, I got a message that one of my children’s classmates had lice.  Ok.  What was amazing was that the mother posted it herself to the group, stated that her child had already been effectively treated, and recommended everyone to fine comb their child’s hair. 

I’m shouldn’t be judgy – but I’m so impressed.  Let’s be honest – when it comes to parent groups – social media or WhatsApp – the health advice isn’t always so sound.   But I love that, in this case, this is exactly what should happen!  I’ll explain why:

  1. Lice love clean hair, lice love dirty hair – lice really love a nice scalp to chew on.  So having lice shouldn’t be stigmatising.

  2. The most effective way of preventing lice is for everyone to regularly fine comb children’s hair with a detection comb (cheap and available in your chemist).   Mythbusting:  children may not have any itching in first few days or weeks of having lice so just if you only check if your child has an itchy scalp, lice may already be there for a few weeks!

  3. We do need to effectively treat lice.  While there are, of course, more serious health conditions untreated lice infestations can cause sores, skin infections, and short-term hair loss from repeated scratching.

So, let’s talk more about lice — and maybe save you some €€€ on buying unnecessary products.

How are they spread: Lice do not jump, fly, or live on cats/dogs. Head to head contact is a route of transmission. Experts are still out on how well and how long lice can live on objects such as hats or brushes but probably don’t live longer than 48 hours at most. They live by feeding on blood and can’t live more than 2 days without a meal.

The best way to prevent them is to wet comb your child’s hair once a week, using a detection comb (these are available in pharmacies quite cheaply; they are finer than your normal styling comb). This will help to find head lice infection early and can  reduce the number of people who will get infected.

What doesn’t work to prevent them: There is no good evidence that any marketed repellent sprays, alternative preventive products, headbands, or electronic combs work. Do not use treatment products as a preventive measure; they should only be used when infection is present:  when you can actually see a living, moving bug. The treatments are safe, but can make scalp flaky and itchy if over-used.

Mythbusting – one more time for those in the back: Itching is not a good way to know if you have them!  Some people do not have the itchy reaction to bites for up to 6 weeks after being infested!  Many people will continue to have some itchiness after treatmetn due to scalp irritation.

How to treat:

Treat everyone in family who is infected at the same time  so that untreated people don’t infect the treated people again. You can discuss with your registered pharmacist for best advice. Read the instructions and follow them – each product is slightly different.  Here are the ones that have been proven to work effectively:

  • Isopropyl myristate (Full Marks Solution™)

  • Dimethicone 4% (Hedrin™) Hedrin

  • Permethrin (Lyclear Dermal Rinse)

  • Master level tip:  repeat one week later – even if the instructions recommend one application only. The reason for this is that no treatment is guaranteed to kill un-hatched eggs and these hatch out over about one week. Check hair about 2 days after the repeat treatment. Once treatment is complete and has gotten rid of the lice, it is important that you return to your practice of weekly wet combing, to check the hair.  If treatment does not get rid of infection, a second treatment is recommended following check of compliance with treatment. After that, check with your GP if you need a third line.  

Does my child have resistent lice? This is a popular myth.  Check the source. This is usually promoted by professional hair lice services, which if you really can’t handle doing it yourself at home, by all means, employ. But most mothers are able to do this at home.  Where does this idea come from?  In the past chemical insecticides were used to treat head lice. Oil based products are now recommended in Ireland. They usually include dimethicone or similar that has a physical “smothering” effect so the lice do not get resistant. If you are having trouble, your GP can prescribe stronger treatment.

What treatments don’t work:

Mousses, rinses with lower concentrations of permethrin, shampoos or repellents are much less effective as they contain low concentrations of the active ingredient, or don’t allow for sufficient contact time.

30 minute hot air blow drying hasn’t been show to work, and is likely to burn/distress your child.

What about the household?

  • Wash the child’s clothes, towels, hats, bedding  in hot water and/or dry on high heat if they were used within 2 days before head lice were found and treated. If you don’t want to wash or item can’t be washed, just seal in a plastic bag for 2 weeks.

  • Everyone in the house should also be checked and treated if necessary.

Alternative/Natural Treatments/prevention:

Alternative Products: A number of products containing essential oils such as tea tree and eucalyptus oil are marketed as ‘natural’ treatments for head lice. They have all failed multiple clinical trials. There has been some early evidence that tea tree oil and lavender oil works at repelling – not killing – lice from inanimate objects (coats, hats, etc) but not on people.  The few trials done on objects – NOT people! – suggest a concentration of 10% tea tree oil and 1% lavender oil. Do NOT put this on your child’s head. Best case, it might reduce potential transmission of lice on the school coat rack. Worst case, your child’s coat just smells amazing. I’ll be honest, I was interested when I read this paper in a pharmaceutical journal back in 2019, so I tried it on my pre-school son’s school outerwear. Loving the smell.  It does not, however, replacing weekly wet-coming at bathtime.

Mechanical removal of lice “wet combing” is less effective (around 57%) at treating infection than recommended chemical treatments.  It is the recommended first line treatment, and can work.  So why does it fail?  To be effective, it is labour intensive and requires a lot of commitment on the part of parents and cooperation from the child. It needs to be done every 4 days for at least 2 weeks until there are no lice or nits seen for 3 sessions in a row.  Many parents or children give up before getting to that point.   Wet combing, however, is usually used for small infants who are too young for chemical first-line treatments.



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