At a mental health conference in Glasgow recently, Dr Terry Lynch had a very clear message: anti-depressants are being massively over-prescribed in Scotland. The author of Beyond Prozac, which takes issue with conventional medical practices, used to be a GP prescribing successive generations of anti-depressants and tranquillisers, but increasingly he began to feel uneasy.

''Each time we saw the same pattern,'' he says. ''A new drug appeared. People liked it. The profession loved it and hailed it as a wonder drug. Then 10 to 20 years later problems arose and the truth emerged that at best this drug made little difference.''

Dr Lynch believes Seroxat - the best known of the second generation anti-depressants, known as SSRIs (selective serotonin reuptake inhibitors) - could pose similar problems. ''Some people have a disastrous reaction to them. I see them as stimulants that can trigger anxiety, aggression, and akathisia - a restlessness of the legs that can be distressing - and it is known that patients prescribed SSRIs have committed suicide. These drugs scare me,'' he says.

It is clear, though, that many people disabled by severe mental illness credit Seroxat with making their lives bearable. Emma Wallace, a 38-year-old cellist with the London Symphony Orchestra has arms covered in scars, a legacy of 17 years of cutting herself with knives and razor blades. She had contemplated suicide and suffered from chronic insomnia, after being badly abused as a child. Three weeks after starting a course of Seroxat her life was transformed. She said of her doctor: ''I had been living in a prison and he had opened the gates.''

Yet in others, Seroxat appears to have had the opposite effect. Retired headmaster, Colin Whitfield, 56, killed himself two weeks after starting a course of Seroxat. Recording an open verdict, the Brecon coroner said the drug should be withdrawn until its safety could be fully investigated.

In June, 20-year-old Natalie Houston from Dunfermline escaped a jail sentence for an assault on another woman in a nightclub after the sheriff accepted that she had not been warned about the possible side-effects of taking Seroxat. This followed a landmark case in the US where the manufacturers, GlaxoSmithKline, were ordered to pay $6.4m ((pounds) 3.7m) in damages to the family of Donald Schell. The 60-year-old killed his wife, daughter, and granddaughter before turning the gun on himself two days after taking the drug (called Paxil in America). It contributes around (pounds) 2bn to GSK's annual turnover.

Derek Scott, 33, of Dundee, was first prescribed Seroxat in October 2000 for panic attacks and agoraphobia. ''After taking only a few tablets I began to feel suicidal,'' he says. ''Because I was afraid of being committed, I didn't tell my GP. I felt agitated all the time and had a great urge to punch one of my lecturers. I couldn't sleep and had sensations like electric shocks. When I told the doctor about these symptoms, he increased the prescription until I was on the maximum dose. When I tried to come off Seroxat the withdrawal symptoms were horrendous. I started staggering around like a drunk and once I was hit by a truck. I'm still on 40mg a day. Some people have been helped by it but others suffer debilitating side-effects such as mine. I'd like to see it banned.''

But how do we distinguish between the effects of the drug and the effects of the mental illness it is intended to treat? As GSK point out, both violence and suicidal thoughts are features of depression and anxiety disorders. A spokeswoman for the company told The Herald: ''Depression is a potentially deadly disease and Seroxat is an effective treatment that since its launch has helped tens of millions of patients worldwide lead fuller and more productive lives.'' She says data showed Seroxat and other SSRIs reduced violence and aggression and there was ''no compelling evidence'' linking it to an increased risk of suicide. She points out that as anti-depressant usage has increased, suicide rates have fallen. ''Seroxat helps to prevent suicide and associated suicidal thoughts.''

Richard Norris, director of policy for the Scottish Association for Mental Health (SAMH), believes the problem with such assertions is that a small number of users (2%-3%) may display a dangerously atypical reaction, not picked up in random trials. ''When someone is very depressed, it will make their thoughts morbid but also reduce their level of activity so they don't have enough energy to act on them. One risk is that a drug like Seroxat will lift the energy level in some patients before suppressing their morbid thoughts.''

Dr David Healy, director of the University of North Wales department of psychological medicine and a world authority on Seroxat, says: ''I'm not in favour of withdrawing Seroxat because some of the people I treat are so disabled by their condition that they consider it worth the risks. My concern is that some people who have had no previous hostile thoughts get those thoughts after going on to the drug. Also some people have committed suicide after going on to Seroxat. Patients need to be told about these risks.''

The patient information leaflet does not mention them.

Now Nice, the National Institute for Clinical Excellence, which decides which drugs should be available on the NHS, is recommending that people with mild depression should be offered anti-depressants only when simple interventions such as talking therapies, exercise regimes, and dietary advice have failed to produce a satisfactory response.

A spokeswoman for the manufacturers says: ''In clinical trials, 60% of patients who took a dummy pill experienced side-effects. Most people (on Seroxat) do not get side-effects.'' The statement ''These tablets are not addictive'' used to appear in GSK's patient information leaflets but was recently removed, though the company still denies Seroxat is addictive. We realised that it did not add to patients' understanding of what to expect when they stopped taking the product,'' said the spokeswoman. She added: ''We acknowledge that patients may experience symptoms on stopping Seroxat.''

Dr David Healy says: ''In GSK's own clinical trials using healthy volunteers and in my own experience around half of patients display withdrawal symptoms such as electric-shock sensations in their limbs and feelings of anxiety. A smaller group have severe symptoms, such as disturbing thoughts and violent dreams. A few have such severe symptoms that they are unable to come off the drug at all. Around half of patients referred to me because they are having difficulty coming off Seroxat are in this position.''

Recently, members of the Online Seroxat Users Group met with the Medicines and Healthcare Products Regulatory Agency to put their case for having Seroxat banned. Meanwhile, 6500 British Seroxat users have joined a group legal action against GSK being organised by Mark Harvey of the Cardiff-based solicitors, Hugh James. All claim to have suffered serious side-effects or withdrawal symptoms from taking Seroxat. Later this month they should hear whether they will receive legal aid.

GlaxoSmithKline says: ''No treatment is perfect for every individual patient and it's a matter for the doctor, in conjunction with the patient, to decide exactly what is the best treatment for them.''

Dr David Healy says: ''I certainly wouldn't ban Seroxat. I still prescribe it. The problem is that people with mild depression are being given the idea that these things are harmless. If they knew the facts, I think many would opt for self-help instead.''

The lowdown on anti-depressants

l Seroxat is one of the biggest-selling anti-depressants in the world. It works by boosting the level of serotonin in the brain - a substance that influences our ''feel good'' factor. For the past 10 years

it has been used to treat millions of people suffering from stress anxiety and depression. Last year 400,000 people in Britain were

prescribed Seroxat.

l Second-generation anti-depressants are known as SSRIs - selective serotonin reuptake inhibitors - of which Seroxat is the best known.

NB: anyone wanting to come off Seroxat or any other

prescribed medication should consult their doctor before altering the prescribed dose.

l Though the latest General Household Survey indicates that the incidence of depression in Scotland is no higher than elsewhere, our spending on anti-depressants ((pounds) 6 per head) is twice as high in Scotland as in London and more than 40% higher than most of England.

l Advice on all anti-depressants is available on the UK Psychiatric Medication Helpline: 020 7919 2999. The Depression Alliance offers information on all forms of treatment for depression: www.depressionalliance.com