Antidepressant drugs, such as Seroxat, could make people aggressive, or even homicidal, a leading specialist has warned.
Experts are currently reviewing research on antidepressants
Dr David Healy, a North Wales psychologist, has previously raised concerns over suicide risk linked to the class of drugs, known as SSRIs.
He is now warning that even healthy people have become unaccountably aggressive in studies into the drugs.
But drug companies say there is no increased risk linked to SSRIs.
Dr Healy, director of Cardiff University's North Wales department of psychological medicine at has previously warned SSRIs (selective serotonin reuptake inhibitors) could be linked to an increased risk of suicide.
Last year, the Department of Health said no SSRIs, except for Prozac, should be given to under 18s after a review by medical experts which looked at the safety of SSRIs after concerns over suicide risk.
The Expert Working Group on SSRIs is now looking at data on adult use of the drugs.
Dr Healy said research had also shown that even some healthy volunteers who took part in trials of SSRIs became "hostile", a clinical term which can include serious aggression and even homicidal behaviour.
He highlighted one trial of Seroxat in the late 1980s and early 1990s which found three out of 271 healthy volunteers became hostile, compared to none of those who were taking the dummy pill.
He says while this only equals around 1.1%, it could translate to a large number of cases among those taking the drug worldwide.
Dr Healy said other research had also raised concerns about increased aggression in children on SSRIs.
He told BBC News Online: "I'm not saying these drugs should be banned, but people should be warned about these risks when they are put on these pills.
"These drugs can be really excellent for people, but it may be they are not suitable for some.
"People taking SSRIs, and their families, should be told about the kind of things to look out for during the first few weeks they are on the drugs."
But a spokesman for GlaxoSmithKine which makes Seroxat, said: "Despite what Dr Healy suggests, there is no compelling evidence from our clinical trials that Seroxat causes hostile behaviour in adults.
"When you put the results from all the clinical trials together there is no difference between the rates of hostility for adult patients taking Seroxat and the patients taking dummy pills. This data has been shared with regulators."
He added: "Dr Healy refers to three incidents of hostility or aggressive reaction among participants taking Seroxat in a study including healthy adult volunteers. Each of these incidents was defined by the researchers as either a mild or moderate aggressive reaction. These reactions resolved themselves without further incident.
A spokeswoman for the Medicines Healthcare products Regulatory Authority, which is advised by the Expert Working Group, said it issued its guidance suggesting children should not be given most SSRIs because of the clinical trial data in children which showed an increased rate of a number of harmful outcomes including hostility.
She added: "The review of adult data is ongoing."