Common antidepressants have been linked to an increased risk of young people committing violent crimes.
A Swedish study found that taking the drugs, known as selective serotonin re-uptake inhibitors (SSRIs,) raised the likelihood of someone aged 15 to 24 being convicted for an act of violence by 43%.
No significant association was seen between SSRI use and violent crime in people aged 25 and older.
Previous research has found that children and young adults, but not older individuals, may be more prone to suicidal thoughts when taking the antidepressants.
A number of legal cases have linked the drugs with violent behaviour, but until now research evidence has been inconclusive.
Scientists conducting the new study used data from Swedish drug prescription and crime registries to compare conviction rates of around 850,000 individuals when they were on and off SSRI medication over a four-year period.
Among the four drugs included in the study were fluoxetine (Prozac) and paroxetine (Seroxat), two of the most widely prescribed antidepressants.
The findings, published in the online journal Public Library of Science Medicine, showed that, overall, taking SSRIs increased the likelihood of a violent conviction by 19%.
When different age groups were analysed separately, the study found a 43% raised risk for people aged 15 to 24. For older participants, the association was not statistically significant.
Violent crimes included attempted or actual murders or acts of manslaughter, unlawful threats, harassment, robbery, arson, assault, kidnapping, stalking, coercion and all sexual offences.
The authors, led by Professor Seena Fazel, from Oxford University, stressed that their results did not prove a causal link between SSRIs and violent crime.
They wrote: “The risk increase we report in young people is not insignificant, and hence warrants further examination. If our findings related to young people are validated in other designs, samples, and settings, warnings about an increased risk of violent behaviours while being treated with SSRIs may be needed.
“Any such changes to the advice given to young persons prescribed SSRIs will need to be carefully considered, as the public health benefit from decreases in violence following restrictions in SSRI use may be countered by increases in other adverse outcomes (such as more disability, re-hospitalisation, or suicides).”