When should someone go to the hospital for mental health concerns?

Usually hospitals: admit people for psychiatric reasons if they are suicidal or homicidal, and really mean it, not just use the thoughts to vent. Another common reason is overdose secondary to mental health issues, but here the primary focus is on dealing with physical health, even if O/D was the underlying problem. Lastly, the ER is the go-to place to go when crises occur after normal office hours--for any cause