It is the latest stage in a battle between those who believe so-called lifestyle disorders such as obesity and baldness should be treated, and those who believe they should not be "medicalised".

The debate is not over whether people experience these conditions.

Ever narrowing definitions of `normal' help turn the complaints of the healthy into the conditions of the sick Ray Moynihan

Instead, it is about how they should be defined, and whether they are diseases which can be treated with a pill.

There are fears medicalisation leads people to look to doctors for easy answers, rather than making changes to their lives.

Some critics are also concerned that drug companies are playing too great a part in defining conditions - with profits in mind.

In recent years, drugs such as Viagra to treat male impotence, Propecia for baldness and Xenical and Reductil to combat obesity have been developed.

Writing in the British Medical Journal, Australian journalist Ray Moynihan warned about the "corporate sponsored creation" of diseases.

He said drug companies had been closely involved in the definition and development of female sexual dysfunction as a new category of human illness.

Mr Moynihan said: "Perhaps the greatest concern comes from the flip side of inflated estimates of disease prevalence - the ever narrowing definitions of `normal' which help turn the complaints of the healthy into the conditions of the sick.

"The potential risk, in a process so heavily sponsored by drug companies, is that the complex social, personal and physical causes of sexual difficulties - and the range of solutions to them - will be swept away in the rush to diagnose, label and prescribe."

'Unmet need'

In 1999, an article in the Journal of the American Medical Association estimated that 43% of women aged 18 to 59 had experienced sexual dysfunction.

But some experts have questioned the validity of that figure, which is now widely used.

It was based on a survey of 1,500 women who were asked to say if they had experienced any of seven sexual problems over the last 12 months.

If they said yes to one, they were classed as having sexual dysfunction.

Richard Smith, editor of the BMJ, told the BBC: "The best way to think about this problem is not as a medical problem, not as a female equivalent of male impotence.

"It's a relationship problem, a psychological problem.

"There undoubtedly will be a physical problem for some of these women, but the idea that almost half of US women have some kind of disorder or disease that perhaps needs to be treated is to inflate a problem and think about it in the wrong way."

A spokeswoman for Pfizer, which makes Viagra, said it was simply working on "unmet medical needs".

And Richard Tiner, medical director of Association of the British Pharmaceutical Industry, defended drug companies,

He said: "All that this is doing is just providing an alternative that could be used by doctors if the situation requires it."

'Non-diseases'

Dr John Dean, secretary of the British Society of Sexual and Impotence Research, told BBC News Online: "If you left it fully to those who abjure the pharmaceutical industry and all its works, you would lose an awful lot of valuable research."

All that this is doing is just providing an alternative that could be used by doctors if the situation requires it Richard Tiner, Association of the British Pharmaceutical Industry

But he added: "We do need to be aware of the inherent risks in being blindly led by the pharmaceutical industry."

Dr Dean said conditions did need to be clearly defined.

"We have to label things so we all know what we're talking about."

He said the same debate over labelling was taking place in areas such as obesity or dissatisfaction with body image.

Earlier this year, the British Medical Journal published a survey in which some doctors classed infertility, obesity and depression as "non-diseases".

The list was topped by ageing, work-related problems and boredom. The top 20 also included jet lag, cellulite, and anxiety about penis size.