Antidepressants are typically the “go-to" medication for moderate to severe depression because so many different types are available, including SSRIs, SNRIs, tricyclic antidepressants and MAO inhibiters.
Selective serotonin reuptake inhibitors (SSRIs) are among the most popular because they are considered relatively safe and effective at treating symptoms of depression. SSRIs work by blocking the reuptake of serotonin in the brain. Serotonin is a neurotransmitter that may play a large role in mood stabilization. Balancing the chemical allows the brain to send and receive signals related to your mood more efficiently. Examples of SSRIs include Prozac, Celexa, Zoloft and Paxil. Serotonin and norepinephrine reuptake inhibitors, or SNRIs, work in a similar fashion, except they also block the reabsorption of norepinephrine, a chemical that may play a role in anxiety disorders. Examples include Cymbalta and Effexor.
Tricyclic antidepressants (TCAs) have been around since the mid-20th century and were the mood disorders medications of choice until SSRIs appeared on the scene. TCAs work by increasing serotonin and norepinephrine levels in the brain while simultaneously blocking the action of acetylcholine, another neurotransmitter thought to play a role in mood regulation. TCAs still available in the United States include Elavil, Tofranil and Norpramin.
Monoamine oxidase inhibitors (MAOIs) were the first antidepressants created, according to the Mayo Clinic. While they are highly effective, they also carry a significant risk of dangerous side effects and require major lifestyle changes. Like their successors, they work by balancing the neurotransmitters thought to be responsible for mood control. However, they are not as selective as their successors; they also block other chemicals in both the brain and the digestive system. Patients taking MAOIs receive a long list of foods and medications they must avoid, including a variety of cheeses, certain meats, pickled foods and alcoholic beverages.