Intuitively, people sometimes wonder whether asking about suicidal thoughts might increase the risk of self-harm and suicide. Dazzi et al. (Reference Dazzi, Gribble, Wessely and Fear2014) conducted a literature review and concluded that there is no evidence for this. However, unlike the conclusion of the authors, this does not necessarily imply that current ethical concerns about enquiring about suicide in research studies could be relaxed.

The key issue for ethical approval is an increased risk of death or other serious harm, i.e. in the context of suicide research completed suicide and attempted suicide with serious consequences. In all the studies mentioned by Dazzi et al. suicidal ideation was measured, not completed suicides. Given that completed suicide is a rare event, investigators had no other option, but it does make interpretation of the studies more difficult.

If suicide was often the result of careful deliberation, one would not expect that limiting the amount of paracetamol people can buy in one visit to a particular shop would influence suicide rates. It is easy to go to another shop and buy another package. However, restricting the amount of paracetamol people can buy has reduced the number of completed suicides with a paracetamol overdose (Hawton, Reference Hawton2007).

There are also sometimes suicide clusters, whereby people commit suicide after a person they can identify with (a celebrity figure or a classmate) committed suicide, and reporting in the media does seem to influence this (Gould et al. Reference Gould, Kleinman, Lake, Forman and Midle2014). In these so called copycat suicides the motivation to commit suicide is influenced by the option being brought to one's attention. It seems unlikely that only being informed about completed suicides, can trigger another completed suicide. Asking questions about suicidal ideas might have an influence as well, but this is impossible to measure.

The key issue is that one can never exclude that a particular research participant might decide to commit suicide after participating in a study asking questions about suicidal ideation. Ethical committees have to weigh this hypothetical risk against the possible scientific benefits of the study, and the scientific benefits may be limited, if one only is able to study suicidal ideation and not completed or attempted suicide.