Antidepressant medications are commonly used to treat conditions like depression and anxiety, with SSRIs being the first line of treatment due to their effectiveness for moderate to severe depression while having fewer side effects than other classes of antidepressants. SSRIs work by limiting the reabsorption of serotonin into presynaptic cells, increasing extracellular serotonin levels. Psychotherapy is also used alongside antidepressant medications to treat the underlying causes of these conditions.