Used as an antidepressant in the treatment of major depressive disorder, particularly in cases where other therapies have not been effective. It functions by inhibiting monoamine oxidase enzymes, thereby increasing the levels of neurotransmitters like serotonin, norepinephrine, and dopamine in the brain. This helps improve mood and alleviate symptoms of depression. Due to its mechanism, it requires dietary restrictions to avoid interactions with tyramine-rich foods, which can lead to hypertensive crisis. Its use has declined with the development of newer antidepressants with fewer side effects and dietary limitations.