Children and adolescents are twice as likely to exhibit suicidal or aggressive behaviour if they take commonly prescribed antidepressants, according to a new study.

Researchers also found that reports on clinical trials by drug companies frequently downplayed the most serious side-effects, which they only discovered by looking at the raw patient data.

The study, published in the British Medical Journal (BMJ), was carried out by researchers from Denmark who looked at clinical trial reports and raw data relating to more than 18,500 patients.

It found that drug companies described more than half of suicide attempts as the “worsening of depression” or “emotional liability.”

When researchers analysed the medical reports, they did not find evidence of increased cases of suicidal behaviour among adults, however the risk was at least double for those aged under 18.

“We suggest minimal use of anti-depressants in children, adolescents, and young adults, as the serious harms seem to be greater, and as their effect seems to be below what is clinically relevant,” the BMJ paper said.

The report comes days after the National Society for the Prevention of Cruelty to Children (NSPCC) said mental health services offered to children in Britain are “inappropriate.”

Figures released by the NSPCC show 90 percent of psychologists, GPs, teachers and social workers believe mentally ill children face problems accessing therapy.

But responding to the BMJ paper, the charity MIND warned against making a link between mental health problems and aggression, saying this “is often exaggerated”

Stephen Buckley, Head of Information at Mind, added: “However, we know from anecdotal evidence that some people report feeling suicidal or may experience aggressive feelings when taking certain antidepressants. This research provides some data on the link in young people, though we still need to understand more about why the link exists.

“Current NICE guidelines on treating moderate to severe depression in under-18s indicate that antidepressants should be offered only in combination with a talking therapy and with additional safeguards to check for any adverse reaction to the medication, including aggressive or suicidal feelings. Parents or carers should be involved in discussions about treatment choice and should be made aware of any risks.”

Commenting on the findings, the BMJ report’s lead author Tarang Sharma said she was astounded by the extent to which the drugs’ most dangerous effects were “downplayed.”

“What they are doing is wrong. They give a very inaccurate picture of what the true harms [side-effects] are,” she told the Independent.