Head lice are insects that live on the scalp and neck. Although head lice may be embarrassing and sometimes uncomfortable, they don't usually cause illness. However, they won't clear up on their own and you need to treat them promptly.
This factsheet is relevant for both adults who have head lice and parents of children with the condition.
Head lice are wingless insects. They are grey or brown and are about 1- 3mm in length when fully grown (the size of a sesame seed). Female head lice lay eggs that are smaller than a pinhead and these attach to your hair close to the scalp. The eggs hatch about seven to 10 days later. Young lice (nymphs) take about 10 days to become adults capable of laying new eggs.
When head lice hatch they leave empty shells called nits attached to the hair. Nits are white and can be mistaken for flakes of dry skin. Unlike dandruff, nits stick to the hair and you won't be able to remove them with normal shampooing.
For many people, head lice cause no symptoms.
They can give you an itchy scalp which may be worse behind your ears or on the back of your neck. If you scratch a lot, the skin can become broken and infections may develop.
Another sign that you may have head lice include nits stuck to the hairs as they grow out. If you spot nits then you need to make a further investigation.
Head lice aren't always to blame for your symptoms. For example, an itching scalp can be due to other causes such as eczema and dandruff. Eczema may be triggered by repeated treatments with insecticides.
Some people feel they have an infestation with lice because they know of others who've been affected. For this reason it's essential to have a confirmed diagnosis before starting treatment.
Anyone can get head lice, but they are most common in children aged between four and 11. This may be because of their close contact with each other at school. Girls seem to be more likely to get them than boys.
You can only get head lice through head to head contact. They cannot hop, fly or swim.
Head lice can only live for a short time away from the scalp and those found away from the head are usually dying.
Head lice can be found in all types and lengths of hair - having head lice is not a sign that your hair is dirty. They are just as often found living in clean hair.
Head lice are hard to spot on the hair but you can remove and then identify them by combing them out. Comb the hair in sections using a special fine-toothed comb, available from pharmacies.
You will probably find it easier to comb the hair when it's wet, and applying hair conditioner is recommended as head lice can move quickly in dry hair. Comb the entire length of the hair from root to tip. After each stroke, check the comb for lice. You can also comb hair over a piece of paper, a white tissue or a bowl of water, which you can then check for lice. It will probably take you about 10 to 15 minutes. Rinse off the conditioner afterwards.
If you're in doubt about what you've found, you can tape a suspected louse to a piece of paper and ask a health professional such as a pharmacist or GP for confirmation. They will be able to advise you on suitable treatments. Infestation is only confirmed if you find a live head louse.
Treatment should only be applied when live lice are found on the head. If you do confirm head lice infestation, there are two main types of treatments available:
Insecticide products contain synthetic or natural insecticides or other chemicals that kill lice and eggs. These are available in a variety of preparations. No treatment kills all the eggs. You will usually need at least two applications of the product, seven days apart, so that any lice that hatch from the eggs after the first treatment are also killed. Insecticides can cause side-effects such as scalp irritation. Only use them if you're sure there's an infestation.
Always use these products exactly as directed on the label and ask your pharmacist for advice if you're unsure about which product is best for you.
If you're pregnant or breastfeeding you should check with your pharmacist or GP before using any insecticides. Don't use insecticide products to treat children under the age of two.
This is a method of removing lice with the regular use of a fine-toothed comb (teeth must be 0.2 to 0.3mm apart). You need to spend approximately 20 to 30 minutes combing through the entire head of hair every two or three days for at least two weeks. It's important you keep doing this until there have been three consecutive sessions without seeing any lice.
Wet combing doesn't involve strong chemicals, and lice can't become resistant to it. It can also be used for routinely checking the hair for infestation.
Whichever treatment you use, a follow-up check using a fine tooth head lice comb should be carried out a few days after the course of treatment.
If you do find any eggs, it doesn't necessarily mean that the treatment has failed - the lice may have been killed and you could just be seeing empty egg cases. If you do find a live adult louse, it may be because you've been re-infested.
Treatment does sometimes fail, often because insecticides aren't used properly. Lice can also become resistant to one or more insecticides. If this happens, you may need to use a different insecticide or try wet combing.
The best way to prevent head lice spreading is to check your whole family regularly and if live lice are found, to treat them as soon as possible.
It's important to check your own hair and your children's hair if you've been in contact with someone with confirmed head lice, so that all cases can be treated at the same time.
To minimise head lice spreading to other people, and to prevent you or your child getting them again after treatment, it's essential to tell everyone you or your child has been in contact with about their possible exposure. They can then be checked and treated if necessary as soon as possible. This includes children and staff at schools and nurseries, as well as other family members such as grandparents. However, you don't need to keep your child off school as it's likely they had head lice for several weeks before you found them.
There's no need to treat bedding, carpet or furniture with insecticides. Head lice don't survive away from the scalp and can only pass from person to person by head to head contact. Pets don't spread human head lice.
The following actions may help to prevent infestation/re-infestation:
Studies have shown head lice repellents aren't effective.
Your State Health Department
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Nash B. Treating head lice. BMJ. 2003; 326(7401): 1256.
Queensland Health. Head Lice. [online] Brisbane, QLD: The State of Queensland (Queensland Health). c2009 [Last updated 5 Aug 2010, accessed 13 Jul 2011] Available from: http://access.health.qld.gov.au/hid/InfectionsandParasites/Parasites/headLice_fs.asp
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Last published: 30 July 2011
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