National guidelines state that combing the hair is a better way to tackle the problem of head lice than using chemical medications.

But research by three leading consultants in communicable disease control has found that although wet combing is the best way to diagnose infection, it is not effective as a treatment.

Instead, the experts have concluded that chemical medications are the only method that has been demonstrated scientifically to be an effective way to combat the problem.

They say that the treatments, based on pyrethroids, malathion and carbaril, should be applied to the head seven days apart.

New guidance needed

Combing the hair is a good way to spot head lice

The authors of the report have called for national information leaflets to be rewritten and for their recommendations to be used as guidance notes for new local policies and protocols on the treatment of head lice for parents, schools and health professionals.

They say that claims that head lice can be resistant to licensed treatments are more likely to be due to inappropriate use, or to people imagining that they have an itch.

The researches say that the true prevalence of head louse infection is probably lower than is commonly thought.

They argue that head lice are not a serious health problem in the UK, and that they rarely, if ever, cause physical health problems other than itching of the scalp.

Major flaws

The Community Practitioners' and Health Visitors' Association (CPHVA) said there were "major flaws" in the study.

Instead, the CPHVA, which represents school nurses, urged parents to stick to combing and inspecting their children's hair as the best way to tackle infestation.

Sue Botes, CPHVA policy officer, said: "Chemicals do work for some children, if they have highly motivated parents prepared to make regular inspections and use the treatment appropriately.