SSRIs relieve symptoms by blocking the reabsorption, or reuptake, of serotonin by certain nerve cells in the brain. This leaves more serotonin available, which improves mood. SSRIs (citalopram, escitalopram, fluoxetine, paroxetine, and sertraline) generally produced fewer side effects when compared with tricyclic antidepressants. However, common side effects include insomnia or sleepiness, sexual dysfunction, and weight gain. They are considered an effective treatment for all anxiety disorders, although the treatment of obsessive-compulsive disorder, or OCD, typically requires higher doses.
