Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
Call local emergency services or go to an emergency department if there is a suicide attempt, a specific plan with intent to act, an immediate threat of violence, or another immediate danger.
If another person's behaviour puts you at risk, move to a safer place when possible and contact emergency or domestic abuse services.
Seek urgent help if you or someone else has suicidal thoughts, escalating self-harm, severe substance use, or feels unable to stay safe.
Contact an urgent mental health service, crisis service, or medical professional available in your area.
Arrange a routine mental health appointment if long-standing problems with self-esteem, criticism, anger, empathy, or relationships are causing distress or disrupting daily life.
Help is also appropriate for depression, anxiety, substance use, or repeated relationship breakdowns, whether or not NPD is the cause.
Every sign above is quoted from the sofidex article on Narcissistic personality disorder. If you are not sure, err upward — it is always reasonable to be checked.