The basics - How to treat cases of head lice

Now the new school term has started, GPs are more likely to encounter this problem. By Louise Newson

Head lice are a common problem - as many as 3 million people a year in the UK catch head lice.

Each year in the UK, the NHS and the general public together spend a staggering £29 million on head lice treatments. However, many patients still delay treatment because of the embarrassment associated with this problem.

Head lice are extremely contagious. Close contact or sharing personal belongings, such as hats or hairbrushes, puts people at risk. Children ages 3-11 and their families are most affected. Poor personal hygiene is not a risk factor for catching head lice.

Considerable social stigma is associated with infection, which may cause psychological distress in the sufferer.

The most important step in treating head lice is to treat the person with lice and other family members at the same time

Human head lice (Pediculus capitis) are ectoparasites with an obligatory blood feeding habit, which requires them to feed on their host's blood several times each day. Head lice are wingless insects and are about the size of a sesame seed. The eggs, called nits, are even smaller - almost like a dandruff flake. Lice and nits are easiest to detect at the neckline and behind the ears.

The average person with head lice has about 20 lice. During their 30-day life, 20 lice will lay 2,652 eggs.

After mating, a female head louse keeps spare sperm in a special container in her body (spermatotheca), so that she does not have to mate again, but can use the sperm she has kept.

Head lice can live for three days away from the head and eggs can survive for five days. Therefore, they could be spread by sharing hats or helmets, combs, brushes, earphones or bedding.

Infestation with head lice is essentially harmless and most cases are without symptoms.

Many people do not know that they have lice until pruritus develops as a result of sensitisation to louse saliva, which may take up to three months to develop after initial infestation.

Secondary infection may occur as a result of bites being scratched. Bites may also become infected by the bacteria carried on the lice or in their faeces. Head lice are actually one of the commonest causes of pyoderma of the scalp.

The most important step in treating head lice is to treat the person and other family members at the same time.

Head lice infestation should be treated using lotion or liquid formulations. Ordinary shampoos are diluted too much in use to be effective. Alcoholic formulations are effective but aqueous formulations are preferred in patients with severe eczema or asthma, and in small children.

Insecticides available are malathion, phenothrin and carbaryl. The normal advice is to treat once and repeat seven days later in order to kill any lice from eggs that survived the first application. Cure rates with chemicals are 70-80 per cent.

One study has shown that 'Bug Buster', a kit comprising four fine-toothed combs with conditioner, applied four times over two weeks, is a very effective method for eradicating head lice.

The conditioner causes the louse to lose its grip on the slippery hair. This treatment has the benefit of not exposing the person to unnecessary chemicals and reduces the likelihood of the lice becoming resistant to medications.

Dimeticone is a fairly new silicone-based treatment. It is not a chemical insecticide; it works by coating the lice and suffocating them. So far, it seems to be a safe treatment with a cure rate of 70 per cent.

Treatment failure
Treatment failures often result from the product not being used in the correct way. For example, if not enough lotion is used, especially for children with long hair.

Using a hairdryer after applying the treatment is not advisable because the heat may alter the lotion and prevent it from working effectively. Chlorine in swimming pools can also interfere with the action of treatments. Treatment failure can also be due to resistance, in which case an alternative treatment should be given.

Alternative treatments
There are a number of herbal products such as tea tree oil and neem seed oil, and methods using electric combs, which have been suggested as alternative treatments for head lice.

  • Dr Newson is a GP in the West Midlands

The Bug Buster technique

1. Wash the hair as normal.

2. Apply conditioner liberally, including the full length of long hair.

3. Lay out white tissues over which you will comb the hair.

4. Comb the hair through with a normal comb first, to get rid of any knots.

5. With a fine tooth comb (nit comb), starting from the roots of the hairs, comb out along the complete length of the hair. After each stroke check the comb for lice and wipe it clean. Work systematically around the whole head of hair. Continue for at least 30 minutes.

6. Rinse the hair as normal.

7. Repeat every two to four days for at least two weeks.

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