According to its maker, Pfizer, Viagra, has been used to treat nearly 30m men in 120 countries onver the last 10 years

Men who had resigned themselves to a life of celibacy were suddenly able to perform. With Viagra sparks were rekindled in previously sexless marriages, rescuing relationships which were floundering on the rocks.

But the critics claim that the physical, intimate act which lies at the heart of humanity has now been comprehensively medicalised by Viagra.

From the young, healthy man who is encouraged to constantly question his performance to the elderly man who can never hang up his boots, Viagra they argue, has raised expectations and lowered satisfaction by making everyone sign up to the ideal of non-stop bustle in the bedroom.

"You can't blame Viagra for single-handedly creating a society in which a man is judged by the size of his erection, and a woman for her ability to arouse one," says Lori Boul, a psychologist specialising in sex therapy.

"But it has certainly played its part in making sure those expectations remain alive and well. Viagra - did not in any event mark the medicalisation of sex.

From the Greeks and herbal aphrodisiacs to the Victorians and their rather more sinister-sounding electric belts, man has long looked for ways to help his member out with varying degrees of success.

Twentieth Century innovations saw the most desperate even opt for injections straight into the organ. But the difference with Viagra was that it actually worked, and that everybody could get their hands on it.

If you can't get Viagra on the NHS - and access to Viagra is restricted to those with very specific conditions - then a quick flick through your spam should do the trick.

The British Medical Association recently argued that NHS access should be widened to stop men resorting to Viagra bought on the internet which could be both fake and harmful.

So if anything, the next decade may see more and more men seeking help. But what of the partners who are expected to deal with the consequences of Viagra?

Dr John Dean, president-elect of the International Society for Sexual Medicine and an ardent advocate of Viagra, concedes that one of the problems of the last decade is the fact that women have not been sufficiently involved in the whole process of prescribing Viagra.

According to recent research, half the men who go home to their partners after obtaining a prescription for Viagra don't go back for more.

For some,Viagra has simply confirmed what they have long suspected: women are not all that interested in penetrative sex, and find their partner's new found erections a bane rather than a boon.

"This notion that women simply aren't interested is both patronising and misguided," says Dr Dean. "Of course we mustn't forget the emotional, cerebral aspect to sex. But to suggest that all women want is a cuddle and a chat, while men are completely focused on their penises, is insulting to both sexes.

"Both are interested in both, and the challenge for the next decade is to ensure both get equal attention, particularly with the arrival of more Viagra aimed at women."

Even those who question the overall benefits of this new generation of Viagra medication can agree that it has at least facilitated discussion around a subject that has long been taboo.

Sex therapists have noted that some of the most restrictive Middle Eastern states find the discussion of sexual relations - within marriage at least - easier than in many Western societies. "It has opened up the discussion of Viagra for people who never felt able to talk about these things," says Ms Boul.

"We live in a country with poor sex education and where many simply do not understand how their bodies work. "But we need to talk more. What we have learnt in the last decade is that you simply cannot send people away with Viagra and expect them to get on with it. It just doesn't work."

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