Suicidal thoughts are common among the general population. Thoughts of self-destruction occur to the majority of people at particular moments in their lives. Usually at times of intense disappointment or frustration.
For most of the people these thoughts flee and pass without any dangerous actions to follow them. However if they persist, as they do to sufferers from depression plans upon them may be formulated and put into action. Occasionally such plans may be quite elaborate and include precautions against any interruption or interference. This situation is dangerous and requires professional help.
In England there are about 5000 suicides each year of which 400-500 involve overdoses of antidepressants. Deliberate self-harm is considered to be 20-30 times commoner.
Not all people who try to commit suicide have psychiatric illnesses, but among those who do, depression is the commonest and 15% of depressed patients eventually kill themselves.