People prescribed anti-depressant drugs like Prozac and Seroxat by their GP may be at increased risk of suicide soon after starting the medicine, the British pharmaceutical company GlaxoSmithKline has acknowledged.

GSK, in the wake of the verdict and a $6.4m compensation award against it over the suicide of Donald Schell in the US, after he killed his wife, daughter and granddaughter while on Seroxat - called Paxil in the US - has complied with a request from the medicines control agency in Britain to issue a warning to doctors and to patients with packets of the drug.

The company insisted the timing of the warning, which was issued two weeks ago, soon after the Schell verdict in Wyoming, was nothing to do with the litigation brought by Donald Schell's remaining family members. GSK has said it will appeal against the verdict.

In fact, the MCA requested all the manufacturers of drugs in the SSRI (selective serotonin reuptake inhibitor) class a year ago to insert the new warning in the summary of product characteristics which goes to doctors and the patient information leaflet.

Concern about the dangers of the SSRIs, which include Prozac, Seroxat and Lustral, has been raised by David Healy, director of the North Wales department of psychological medicine, who gave evidence for Donald Schell's family in their successful litigation against GSK.

In archives maintained by GSK in Harlow, Essex, Dr Healy found early trials of Seroxat on healthy employees of the company before the drug was licensed. He told the court that 25% of those taking part in 34 studies became disturbingly agitated on the drug.

He believes that a minority of those prescribed SSRIs can become violent towards themselves and others, which can end in suicide. In the case of Donald Schell and also of David Hawkins in Australia a couple of weeks earlier, a court decided the pills caused people to murder as well.

Dr Healy, however, is far from satisfied with the warning that the MCA and the drug companies have agreed.

The warning reads: "The possibility of suicide is inherent in depression and may persist until significant therapeutic effect is achieved, and it is general clinical experience with all antidepressant therapies that the risk of suicide may increase in the early stages of recovery."

"The person taking the drug is left thinking he or she has a problem, rather than that the pill caused them the problem," said Dr Healy.