Causes of Suicide

About one in six people who kill themselves leaves a suicide note, which sometimes provides clues as to why.

Suicidal behaviours usually result from the interaction of several factors.

The most common factor that contributes to suicidal behaviour is:


Depression, including the depression that is part of bipolar disorder, is involved in over 50% of attempted suicides and an even higher percentage of completed suicides.

Depression can occur out of the blue, be triggered by a recent loss or other distressing event, or result from a combination of factors.

In individuals with depression, marital problems, recent arrest or trouble with the law, unhappy or ended love affairs, disputes with parents or bullying (among adolescents), or the recent loss of a loved one (particularly among older people) may trigger a suicide attempt.

The risk of suicide is higher if individuals with depression also have significant anxiety.

Individuals with certain medical disorders may become depressed and attempt or complete suicide.

Most disorders associated with increased suicide rates either directly affect the nervous system and brain (as occurs in AIDS, multiple sclerosis, temporal lobe epilepsy, head injuries) or involve treatments that can cause depression (such as certain drugs used to treat high blood pressure).

In older individuals, about 20% of suicides may at least partly be a response to serious chronic and painful physical disorders.

Traumatic Childhood Experiences

Traumatic childhood experiences, including physical and sexual abuse, increase the risk of attempted suicides, perhaps because depression is common among individuals who have had such experiences.


Use of alcohol may intensify depression, which, in turn, makes suicidal behaviour more likely. Alcohol also reduces self-control.

About 30% of individuals who attempt suicide drink alcohol before the attempt, and about half of them are intoxicated at the time.

Because alcoholism, particularly binge drinking, often causes deep feelings of remorse during dry periods, alcoholics are suicide-prone even when sober.

Other Mental Disorders

Almost all other mental disorders also put individuals at risk of suicide.

Individuals with schizophrenia or other psychotic disorders may have delusions (fixed false beliefs) that they find impossible to cope with, or they may hear voices (auditory hallucinations) commanding them to kill themselves. Also, individuals with schizophrenia are prone to depression.

Individuals with borderline personality disorder or antisocial personality disorder, especially those with a history of violent behaviour, are also at higher risk of suicide. Individuals with these disorders tolerate frustration poorly and react to stress impetuously, sometimes leading to self-harm or aggressive behaviour.

Living Alone

Living alone increases the risk of suicidal behaviour.

Individuals who have been separated, divorced, or widowed are more likely to complete suicide.

Suicide is less common among individuals who are in a secure relationship than among single people.

Risk Factors for Suicidal Behaviour

There are many risk factors for suicidal behaviour, including:

  • Male.
  • Painful or disabling illness.
  • Living alone.
  • Economic downturns or debt.
  • Unemployment.
  • Bereavement or loss.
  • Humiliation or disgrace.
  • Hopelessness.
  • Aggressive or impulsive behaviour.
  • Depression, especially when it is accompanied by anxiety or is part of bipolar disorder.
  • Recent hospitalisation for depression.
  • Most other mental disorders, such as personality disorders.
  • Persistent sadness even when other symptoms of depression are lessening.
  • A history of drug or alcohol abuse.
  • A history of prior suicide attempts.
  • A history of suicide or mental disorders in family members.
  • Traumatic childhood experiences, including physical or sexual abuse.
  • Preoccupation with and talk about suicide.
  • Well-defined plans for suicide.

Antidepressants and the Risk of Suicide

The risk of suicide attempts is greatest in the month before starting antidepressant treatment, and the risk of death by suicide is no higher after antidepressants are started.

However, antidepressants slightly increase the frequency of suicidal thoughts and attempts (but not of completed suicide) in children, adolescents, and young people.

Therefore parents of children and adolescents should be warned, and children and adolescents should be carefully monitored for side effects such as increased anxiety, agitation, restlessness, irritability, anger, or a shift into hypomania (when people feel full of energy and cheerful but are often easily irritated, distracted, and agitated), especially during the first few weeks after they start taking the drug.

Because of public health warnings about the possible association between taking antidepressants and an increased risk of suicide, medical professionals started prescribing antidepressants more than 30% less often for children and young people.

However, during this same time, suicide rates among young individuals temporarily increased by 14%

Thus, it is possible that by discouraging drug treatment of depression, these warnings resulted in more, not fewer, deaths by suicide.

When individuals with depression are given antidepressants, medical professionals take certain precautions to reduce the risk of suicidal behaviour:

  • Giving individuals antidepressants in amounts that would not cause death.
  • Scheduling more frequent visits when treatment is first started.
  • Clearly warning individuals and their family members and significant others to be alert for worsening symptoms or suicidal ideation.
  • Instructing individuals and their family members and significant others to immediately call the medical professional who prescribed the antidepressant or to seek care elsewhere if symptoms worsen or suicidal thoughts occur.

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