Oral ketamine reduces the experience of stress in people with chronic suicidality

•Oral ketamine  reduced self-reported stress in people with suicidality.•Six, weekly doses resulted in stress symptoms reducing to sub-clinical levels.•Stress symptoms re-emerged after 4 weeks of no ketamine treatment.•However, suicidality responders had a maintained stress reduction at follow-up.•Exploration of neurobiology of stress response to oral ketamine is warranted.