Head lice (Pediculus humanus capitis) are parasitic insects that only live on humans. They start out as ‘nits’ - tiny, oval, yellowy eggs that attach themselves to the hair shaft. A week later they hatch into ‘nymphs’ and mature into adult lice surviving by feeding on our blood. Lice like any hair whether it’s: long, short, clean or dirty.
Symptoms of Head Lice
- An itchy scalp
- Sometimes a rash on the back of the neck
Recognising when you have head lice
Head lice eggs are creamy brown in colour. The female louse glues them tightly to the base of the individual hairs close to the scalp so that the young lice are able to feed as soon as they hatch. The eggs are pinhead-sized. After 7-10 days the babies hatch and the empty eggshells (nits) remain glued in place. They are easy to distinguish from dandruff as they don’t fall off easily.
Head lice bite the scalp to feed on blood. They take 6-10 days to become fully grown and once mature crawl from head to head and start laying eggs within a week of hatching.
The main symptom of head lice is itching - caused not by the bite itself but by the body reacting to it (an allergic reaction). Not everyone experiences itching.
The best way to find lice is to use a lice detection comb which has tooth spacing of less than 0.3m. The lice get trapped between the comb’s teeth. It works best on wet hair.
Treating Head Lice
The wet combing method: wet the hair and use a special detection comb to trap and pick out the lice. This is time-consuming and needs to be one regularly over several weeks.
Head lice treatment: these include traditional insecticide (eg malathion or ermethrin) to poison the lice or newer physically acting treatment which kills the lice by smothering them. The advantage of the smothering method is that lice cannot build up resistance. Lice treatments usually need to be repeated a week later to kill lice over the hatching period - as lotions don’t always kill louse eggs. There are many suitable over-the-counter treatments but only use treatment if live lice have been found on the head.
If these don’t work you may want to see to speak to your pharmacist or doctor. See a doctor for treatment advice for infants under 6 months.