The use of ketamine nasal spray in the treatment of treatment-resistant depression has shown promising results in a recent clinical trial. Compared to the antipsychotic drug quetiapine, ketamine nasal spray led to higher rates of remission in patients with treatment-resistant depression. This is significant because treatment-resistant depression affects a significant portion of patients with major depressive disorder and is associated with a high economic burden. While esketamine nasal spray is currently the only therapy specifically approved for treatment-resistant depression in Europe, more data comparing its efficacy to quetiapine is needed. However, it is important to note that the use of ketamine nasal spray was associated with a high rate of side effects, including sedation and dissociation.