‘Why were you given that much medication in the first place?” I often find myself wondering that as I treat patients with a history of suicide attempts who have intentionally overdosed on their 90-day supply of medication.

As an inpatient psychiatrist, I see the lucky ones—those who are still alive. Many of these patients struggle with chronic suicidality and shouldn’t be prescribed large quantities of medication as a matter of safety. Yet with regularity they tell me their insurers wouldn’t pay for smaller amounts. I know...