It used to be that men had the upper hand when it came to confidence in the bedroom.

But health experts say ever-younger men are increasingly turning to Viagra in a bid to keep up with modern women inspired by the strong female characters in films such as Sex And The City, starring Sarah Jessica Parker.

Relationship therapists are also seeing a rise in the number of men in their 30s asking about the impotence drug, traditionally prescribed to those more than two decades older.

Health experts believe young men are turning to Viagra to keep up with modern women inspired by Sex And The City, starring Sarah Jessica Parker (pictured)

Experts believe the men feel increasingly emasculated by today's women.

They claim that women, following the example of television and film characters, are more vocal about their desires and demand a higher level of stamina and imagination in the bedroom.

The pressure is causing an increasing number of men to experience 'performance anxiety' and, in extreme cases, is leading to diagnoses of erectile dysfunction, requiring specialist treatment. Dr John Tomlinson, a former GP and trustee of the Sexual Dysfunction Association, said he was hearing from an ' enormous' number of 18- to 40-year-olds worried about sexual problems.

He suggested advertising - such as David Beckham's Armani underwear campaign - glamorises the well-toned male body, which men find daunting because they assume it is what women expect.

He said: 'Men may feel emasculated by modern women and feminism has taken its toll. But most of the problems are psychological. I'm sure many of these men are fuelling the counterfeit drugs industry by buying their Viagra online, so the real picture is likely to be bigger than GPs are reporting.'

There are no official figures for the number of young men taking Viagra because it is not routinely recorded by doctors. Many also opt to seek treatment privately. BUPA said it could not provide data on consultations. However, health experts agreed the average age for men seeking the drug is falling.

Dr John Dean, a specialist in sexual medicine, said when Viagra was introduced ten years ago, it would have been unusual to treat men in their 30s. Now, however, it is common, he said.

Peter Baker, of the Men's Health Forum website, said it is 'well-known' among health professionals that younger men are turning to Viagra.

Relationship experts said the prevalence of pornography in society also left men with unrealistic expectations.

Sex therapist Denise Knowles, of counselling service Relate, said: 'Pornography affects how men see themselves and how they think women will see them. Further pressure comes from the myth that men should know what to do in the bedroom and that women are difficult to satisfy.'

Nearly 6.5 million tablets of Viagra - launched by drugs firm Pfizer in 1998 - were issued in England in 2007, costing the NHS £35million. Research in 2004 found that taking the drug recreationally could affect fertility.