The BBC's James Westhead: Doctors fear patients could be condemned to life on drugs

But the launch on Thursday has sparked fears of a huge new drain on NHS finances.

The BBC's Joe Campbell: Social phobia affects 3m people

Seroxat is already used to treat depression, but researchers have discovered that the drug also helps people suffering from acute shyness - or social phobia.

The condition, which affects around 2% of the public, can leave people unable to eat in public, unable to maintain eye contact and virtually housebound.

BBC's James Westhead on some psychiatrists' concerns over shyness pills

Sufferers can miss out at school and may later turn to alcohol and drug abuse.

Usually, social phobia is linked to other conditions such as agoraphobia, panic disorders and obsessive compulsive disorder for which a patient may already have sought treatment.

Seroxat increases the level of seratonin in the brain, creating a feeling of well-being and self-confidence.

The UK is the first country to approve the drug which is manufactured by SmithKline Beecham and has been used as an anti-depressant in the UK since 1991.

It was the fastest selling anti-depressant drug in the UK in the mid-1990s. In 1996, UK sales grew by 50%.

Social disorders

The launch - hot on the heels of the launch of anti-impotence drug Viagra - has once again raised fears about the impact of 'lifestyle' drugs on NHS budgets.

Some doctors have suggested that it could cost the NHS around £700m ($1.17bn) a year.

However, SmithKline Beecham say this is an exaggeration since the drug will only be prescribed for people with specific social disorders.

The pharmaceuticals giant adds that many of these people already go to their GPs for treatment of associated disorders, such as depression.

Dr John Chisholm of the BMA: Doctors must make hard choices

But Dr John Chisholm, chairman of the British Medical Association's GPs committee, told the BBC: "This is another drug where the potential costs for the health service are very considerable.

"The health service is under-funded and increasingly it is recognised that it is not able to meet all possible needs. That leads us into the very difficult area of making hard choices between one problem and another."

However, Dr Brian Goss of the British Medical Association, said: "It is not a wonder drug to turn anoraks into witty after-dinner speakers, but it will help people with a serious medical phobic condition."