Americans revere personal responsibility. It resonates with our respect for accountability and frontier justice. That may explain why we have a hard time believing that medications could alter people’s personalities or lead them to behave badly. Violence as a drug side effect seems preposterous to patients, pharmacists, physicians and even juries. Trying to use the “Prozac defense” to justify killing or hurting someone is often met with scorn..

Antidepressant prescribing information, for example, warns physicians that, “All patients being treated with antidepressants for any indication should be monitored appropriately and observed closely for clinical worsening, suicidality, and unusual changes in behavior.” Drugs such as citalopram (Celexa), escitalopram (Lexapro), fluoxetine (Prozac), paroxetine (Paxil) and sertraline (Zoloft) carry warnings about aggressiveness, agitation, hostility, impulsivity and irritability.

The stop-smoking medication varenicline (Chantix) also comes with warnings about agitation, hostility, depressed mood and changes in behavior. The trouble with such warnings is that people don’t imagine that these bad things could happen to them.