Head Lice: School, Spread and What Does Not Work
No exclusion, no prevention, and no need to wash the bedding — what the evidence actually supports, and the effort worth abandoning entirely.
Part of the Complete Head Lice Guide.
Key fact: There is no need to keep a child off school for head lice, and nothing reliably prevents them. Both facts contradict a great deal of what circulates in class WhatsApp groups, and between them they save families an enormous amount of wasted effort.
School and nursery
Head lice are not a reason to keep a child at home. The NHS position is direct: there is no need to keep your child off school if they have head lice.
- No exclusion is required, and no "clearance" is needed before returning
- By the time lice are found, they have usually been present for weeks and any transmission has already happened
- Treat promptly once live lice are confirmed, which is the useful action
- Tell close contacts so they can check their own children
- Tying long hair back is a reasonable, low-effort measure at school, though the evidence is limited
When a letter comes home
A letter means someone in the class has head lice. It does not mean your child does.
| Do | Do not |
|---|---|
| Comb everyone in the household that evening, properly, with conditioner | Treat on the strength of the letter |
| Treat only those with a live louse found | Treat "just in case" or as prevention |
| Recheck in a week | Buy a repellent spray |
| Tell close contacts if you do find them | Strip and wash all the bedding |
How to check covers the combing method, which takes 10 to 30 minutes per head and answers the question properly.
How they actually spread
Head-to-head contact, and effectively nothing else. A louse has to crawl from one scalp to another, which needs hair to be touching hair for a sustained moment.
- They cannot jump or fly — they have no wings and no jumping legs
- They die within about a day away from a human scalp
- There is no evidence that lice are transmitted any way other than head to head
- Home matters as much as school — siblings sharing a sofa, bedtime stories, and photographs taken cheek to cheek
- Pets cannot carry them
What to do at home
- Check every household member the same evening, and anyone in close head-to-head contact in the past month
- Treat only those with live lice, and treat them at the same time so nobody reinfects anyone else
- Complete the course, including the second application after 7 days
- Recheck 2 to 3 days after the last application, and again about a week later
- Tell people outside the house who have had close contact — grandparents, sleepover friends, a cousin
The laundry question
Washing bedding, bagging soft toys, hoovering the sofa and boil-washing hats achieve nothing. Lice do not transmit that way and cannot survive long off a head. This is the single largest source of wasted effort in the topic, and it lands on households at the worst possible moment.
If it helps to change the pillowcase, change the pillowcase. Just do not treat it as part of the treatment, and do not let it displace the thing that does work — combing everyone's hair properly and completing the course.
Combs and brushes used by an infested person can be washed in hot water as a reasonable precaution, since they have been in direct contact with the scalp.
Prevention: what is and is not true
| Claim | Reality |
|---|---|
| Repellent sprays stop children catching them | Not recommended, and there is no good evidence they work |
| Tea tree, lavender or eucalyptus oil prevents lice | Unlikely to work, and some irritate the scalp |
| Washing hair more often helps | No. Lice are unaffected by clean hair, and shampoo formulations are too dilute and too brief to treat them |
| Short hair prevents them | No. Hair length makes no difference to catching them, only to how long combing takes |
| Tying hair back helps | Plausible and harmless, with limited evidence. Worth doing, not worth relying on |
| Regular detection combing prevents them | It does not prevent them, but it finds them early, which means less treatment and less passed on |
Treatments that do not work
- Permethrin products — resistance is widespread and they are not recommended for head lice
- Shampoo formulations — too dilute, and rinsed out long before they could act
- Electric combs and vacuum devices — unproven
- Plant oils — tea tree, eucalyptus, lavender and similar are unlikely to work
- Mayonnaise, petroleum jelly, olive oil and similar — messy, largely ineffective, and occasionally dangerous if flammable products are used
- Treating everyone in the family as a precaution — only those with live lice should be treated
Never use veterinary or agricultural insecticide products, paraffin, petrol or any flammable liquid on hair. Serious burns and poisoning have resulted. Head lice are a nuisance, not a danger, and nothing about them justifies risk.
The hygiene myth
Head lice have no relationship to cleanliness, housekeeping, or how often hair is washed. They are extremely common in primary school children, they spread between heads that touch, and catching them says nothing about a family.
The stigma is worth naming because it does damage: it makes parents reluctant to tell the school or other parents, which is precisely the communication that limits spread. Telling close contacts promptly is the most useful thing anyone does in an outbreak, and it only happens where it is not treated as shameful.
If it keeps happening
- Check whether the course was completed, including the second application
- Check everyone at home — an untreated adult with a light infestation is a common source
- Consider a different mode of action if the same product has failed twice when used correctly
- Confirm it is actually recurring — nits stay glued to the hair for months and are not evidence of new lice
- Accept some repetition — in a primary school class with ongoing transmission, a child can genuinely catch them again, and that is not a treatment failure
Repeated courses in a child where live lice are never actually found is a reason to stop and reassess rather than to escalate — see how to check.
No. Head lice are not a reason for exclusion and no clearance is needed to return. By the time they are found they have usually been present for weeks. Treating promptly once live lice are confirmed, and telling close contacts so they can check, are the useful actions. No. Lice do not transmit via bedding, clothing, hats or furniture, and they die within about a day away from a scalp. Washing bedding, bagging toys and hoovering achieve nothing. Combs and brushes used on an infested head can be washed in hot water as a reasonable precaution. No. Repellent sprays are not recommended and there is no good evidence they work, and plant oils such as tea tree, eucalyptus and lavender are unlikely to work and can irritate the scalp. Nothing reliably prevents head lice, though regular detection combing catches them earlier. No. Head lice have no relationship to cleanliness or how often hair is washed, and clean hair is no barrier. They are very common in primary school children and spread wherever heads touch. The stigma is actively unhelpful, because it discourages telling contacts, which is what limits spread. Not on the strength of the letter. Comb everyone in the household that evening with conditioner and a detection comb, and treat only those where a live louse is found. Treating without confirming means using insecticide unnecessarily, which is how resistance develops.Frequently Asked Questions
Should a child stay off school with head lice?
Do I need to wash all the bedding if my child has head lice?
Can you prevent head lice with sprays or tea tree oil?
Does having head lice mean poor hygiene?
A letter came home from school. Should I treat my child?
References
- NHS. Head lice and nits. nhs.uk
- National Institute for Health and Care Excellence. Clinical Knowledge Summary: Head lice. cks.nice.org.uk
- Welsh Medicines Information Centre. Head Lice: Questions and Answers for Healthcare Professionals. wmic.wales.nhs.uk
- UK Health Security Agency. Health protection in children and young people settings, including education. gov.uk
- Burgess IF et al. Randomised, controlled, assessor blind trial comparing 4% dimeticone lotion with 0.5% malathion liquid for head louse infestation. PLoS ONE 2007. journals.plos.org
Medical disclaimer: This article is for informational purposes only and does not constitute medical advice. Head lice treatment should only be used when a live louse has actually been found, and product instructions vary, so always read the leaflet supplied. Always consult a qualified healthcare professional for diagnosis and treatment. In a medical emergency, call 999.