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Pharmaceutical trials show that antidepressants more than double the risk of suicide

In clinical trials, taking antidepressants increases the risk of suicide. This was the conclusion drawn by a meta-study conducted by researchers from ZHAW, as well as the University Clinic for Psychiatry, Psychotherapy and Psychosomatics in Salzburg, that analysed various pharmaceutical studies.

In clinical trials, patients on antidepressants were around 2.5 more likely to commit suicide or attempt suicide than patients who were given a placebo. This is the conclusion drawn by a meta-study conducted by ZHAW Zurich University of Applied Sciences and the University Clinic for Psychiatry, Psychotherapy and Psychosomatics in Salzburg. The study was published in the well-respected psychiatry journal Psychotherapy & Psychosomatics. The researchers therefore suspect that adverse drug effects are also causing additional suicide attempts in real life – and strongly recommend better educating people on the risks of antidepressants. As previous research data on the link between antidepressants and suicide rates was not clear, the researchers analysed data from all antidepressant trials sponsored by pharmaceutical companies that were assessed between 1987 and 2013 by the US Food and Drug Administration (FDA) for the purposes of market approval of the drugs for adults.

Two and a half times as many suicide attempts with antidepressants

In the data under analysis, suicides or suicide attempts were observed in 0.8% of patients on antidepressants and 0.3% of patients on placebo across all the trials that were evaluated. In other words, patients who received antidepressants committed or attempted suicide more than 2.5 times as often than those who were given a placebo. These differences between the treatment groups are not linked to other factors, such as specific depression symptoms or personality traits, because each patient was randomly assigned to their respective treatment group. This was because all the trials evaluated were randomized controlled clinical trials, meaning that the participants were randomly assigned either to a group receiving treatment with antidepressants or to one receiving a placebo. When they were assigned to the groups, neither the doctors nor the patients knew who received the drug and who received the placebo. This randomized ‘double-blind’ method allows the differences to be attributed to the pharmacological effect of the drug.

3,600 additional suicide attempts presumed

Based on their calculations, the researchers estimate that in the clinical trials, 1 in 202 patients given antidepressants attempted suicide due to adverse drug effects, which they would not have attempted without drug treatment (referred to as the ‘number needed to harm’). The researchers also believe that the results would be similar under real-world conditions. ‘Our analysis does not show whether the risk is the same among real-world routine practice as it was in the clinical trials we examined,’ says ZHAW researcher Michael P. Hengartner. ‘However, we can’t rule it out.’ If the actual risk among the general antidepressant user population corresponds to the risk found in the clinical drug trials, this would mean that we would see a total of 3,614 additional suicide attempts in the roughly 730,000 patients taking antidepressants in Switzerland. Educating patients and doctors is therefore even more important. ‘People should be made more aware of these risks associated with antidepressants. Doctors should also carefully weigh the risks and benefits,’ explains the ZHAW researcher.


Dr Michael P. Hengartner, Clinical Psychology and Health Psychology expert group, School of Applied Psychology, ZHAW Zurich University of Applied Sciences, tel. +41 (0)58 934 83 82, email

Tanja von Rotz, Communications, School of Applied Psychology, ZHAW Zurich University of Applied Sciences, tel. +41 (0)58 934 84 08, email