More than 100 people who say they have suffered serious side effects after taking a pill for mental illness are deciding whether to take legal action.

Seroxat was meant to be the wonder drug of the last decade - giving relief to patients with a range of mental health problems.

The manufacturers, British pharmaceutical company GlaxoSmithKline say the drug has transformed the lives of thousands of people.

Seroxat is an effective and generally well tolerated treatment for the management of depression

Dr Alistair Benbow, GlaxoSmithkline

Three million prescriptions for the drug are given out in the UK alone each year.

However, legal action against the makers of the drug has already begun in the US, and could now spread across the Atlantic.

'Nightmare'

John Simmons started taking Seroxat to treat his depression 12 years ago.

He hoped the drug would help him, but he claims that instead he has suffered side effects from a drug that he is now unable to give up.

"You have got things buzzing through your mind, splitting headaches, you just cannot sit still - it is a nightmare."

John's wife Janice has carried out extensive research into the drug.

Mr Simmons says he has suffered side-effects

"I have got piles and piles of paperwork and reports from different places that are recognising this as a problem."

Mark Harvey, solicitor for the action group representing Seroxat patients, said more and more people are coming forward, claiming they cannot come off the drug.

He told the BBC: "A lot of the people accepted this drug because they were assured that it was not addictive.

"And yet quite clearly the stories that are coming through to us on a daily basis show that not only themselves, but also their doctors have clearly been fooled - that it is addictive, they cannot get off this drug."

The action group wants GlaxoSmithKline to put clearer warnings about the side effects of the drug on its information leaflet.

A new version of the leaflet, printed a few months ago, warns that withdrawal from Seroxat should be gradual.

However, they say that withdrawal symptoms are not caused by dependence.

The leaflet also mentions for the first time the word "suicide".

The group are concerned that this puts the blame on the patient's condition, rather than the drug.

Effective treatment

But GlaxoSmithKline say depression gives risk to an increased risk of suicide.

Dr Benbow said the drug is safe

Dr Alistair Benbow, of GlaxoSmithkline, said: "Seroxat is an effective and generally well tolerated treatment for the management of depression.

"It has been used effectively in tens of millions of patients in many countries world-wide, and I think patients have nothing to fear from taking Seroxat."

Dr Benbow said the regulators had scrutinised all the available data on Seroxat.

"I have personally reviewed all the data, and from my personal studies I say there is no credible evidence that Seroxat causes suicide."