Written for Stock My Medicine and clinically reviewed by Hajra Dhanchora, MPharm (GPhC 2216990).
Head lice are the most democratic infestation there is: clean hair, dirty hair, long, short, rich, poor, they don't care, and any child who puts their head next to another child's will meet them eventually. They don't carry disease and they don't jump. What they do is multiply quietly for weeks before anyone notices, which is why the first sign is often a letter from school. Here's how to find them, the two methods that genuinely clear them, and the long list of things that don't.
What do head lice and nits look like?
Lice are grey-brown insects the size of a sesame seed, with six legs, that live on the scalp and feed on blood. They move fast when the hair is parted, which is why you rarely spot one by looking. Nits are the eggs, and later the empty egg cases: tiny yellow-white or brown ovals glued to the hair shaft close to the scalp, especially behind the ears and at the nape. Dandruff flakes off when you flick it; a nit doesn't move. Empty cases, which are white and sit further from the scalp as the hair grows, mean there was an infestation but not necessarily that there still is. Only finding a live, moving louse confirms one.
Head lice symptoms
An itchy scalp is the one everyone knows, but it's caused by an allergy to louse saliva that takes weeks to develop, so a child can have lice for a month with no itching at all, and some never itch. Other signs: a tickling feeling of something moving, a child scratching behind the ears, small red bumps on the scalp or neck, and, in the worst cases, a rash or infected scratches at the hairline. Lice-related "dirt" on pillows is their droppings. None of these is reliable; the comb is.
How to check for head lice
Use a fine-toothed detection comb (teeth 0.2 to 0.3mm apart; a normal comb won't catch them) on wet, conditioned hair. Comb from the roots to the tips in sections, wiping the comb on white paper after each stroke. Check the whole family at the same time, including adults, and check again a week later if you find nothing but the itching continues. Checking weekly during term time, say every Sunday at bath time, catches an infestation before it's established.
How to get rid of head lice: two methods that work
| Method | How | Pros and cons |
|---|---|---|
| Wet combing | Shampoo, apply plenty of conditioner, detangle, then comb every section root to tip with the detection comb. 10 minutes for short hair, 20 to 30 for long. Repeat on days 1, 5, 9 and 13, and check on day 17 | Free apart from the comb, chemical-free, safe for everyone including babies and pregnancy. Needs doing properly all four times; miss one and the newly hatched lice mature. |
| Medicated lotion or spray | Apply to dry hair covering every strand, leave for the time on the pack, rinse. Repeat after 7 days to kill lice hatched from eggs that survived | Quick, and modern products work by suffocating lice rather than poisoning them, so there's no resistance. Not all are licensed under 6 months or in pregnancy; check the pack. |
Which head lice treatment works?
The ones that smother. Dimeticone is the first choice: it coats the louse and blocks its breathing holes, and lice can't become resistant to a physical effect.
- Hedrin 4% Lotion: the classic, left on for 8 hours or overnight, repeated after 7 days. Suitable from 6 months.
- Hedrin Once Spray Gel: a 15-minute version that also claims to kill eggs, so a single application is often enough.
- Hedrin Treat & Go: a leave-in mousse that dries invisibly and washes out after 8 hours; the easy option for a fidgety child.
- Lyclear Express lotion, spray or shampoo: isopropyl myristate and cyclomethicone, 10 to 15 minutes, also a smothering mechanism, with a comb in the pack.
- Derbac-M (malathion): an insecticide, left on for 12 hours, for when a physical treatment has genuinely failed. Not for under-sixes without advice.
Whatever you use, follow with a comb-through to remove dead lice and nits, and check again two to three days after the second treatment. All of these are in our baby and child collection.
What doesn't work
Permethrin-based products, once the standard, are no longer recommended because lice are widely resistant to them. Electric combs, tea tree, lavender and eucalyptus oils, mayonnaise, vinegar, hair straighteners, "repellent" sprays and shaving a child's head have no evidence behind them or are unkind. Head lice can't live more than a day or two off the scalp, so there's no need to hot-wash bedding, boil hairbrushes or quarantine the soft toys; a normal wash of the pillowcase is plenty.
Where do head lice come from, and can you prevent them?
From other heads, by direct contact. Lice crawl; they can't jump, fly or swim, and they don't travel on hats or furniture in any meaningful way. That's why primary-school children, who play head to head, get them most, and why long hair tied back helps a little. You can't prevent them beyond that, and the NHS says so plainly. What you can do is find them early with a weekly comb, which turns a six-week infestation into a one-week one.
School, nursery and the rest of the family
Children with head lice don't need to stay off school; by the time they're found, the class has already been exposed. Tell the school so other parents check. Check everyone in the household the same day and treat only those with live lice; treating "just in case" wastes product and achieves nothing. Adults get them too, usually from their children.
When to see a pharmacist or GP
A pharmacist can confirm an infestation and advise on treatment for babies, pregnancy and children with asthma or eczema, where some products are off-limits. See a GP if two different treatments have failed, the scalp is infected (weeping, crusted or painful, with swollen glands in the neck), or you're not sure it's lice. Our pharmacist can help you choose between the lotions, and the Calpol guide covers a child whose scratching has left them sore.
Frequently asked questions
Do head lice jump from head to head?
No. They walk across when heads touch. The jumping idea comes from fleas, which are a different insect entirely.
How long can head lice live on a pillow?
Up to 24 hours at most without a blood meal, and they're unlikely to leave a warm scalp for a pillow in the first place.
Can you see nits without a comb?
Often, as pale specks stuck to the hair near the scalp behind the ears, but you can't tell live eggs from empty cases by eye, and you can't confirm an infestation without finding a louse.
Why do the lice keep coming back?
Either the treatment wasn't repeated at day 7 (or the combing at days 5, 9 and 13), so hatchlings survived, or the child has been re-infested by an untreated friend or sibling. Re-check the household and ask the school to send its letter again.