There are several types of antidepressant medications used to treat depressive disorders. These include newer medications—chiefly the selective serotonin reuptake inhibitors (SSRIs)—the tricyclics, and the monoamine oxidase inhibitors (MAOIs). The SSRIs—and other newer medications that affect neurotransmitters such as dopamine or norepinephrine—generally have fewer side effects than tricyclics. Sometimes the doctor will try a variety of antidepressants before finding the most effective medication or combination of medications. Sometimes the dosage must be increased to be effective. Although some improvements may be seen in the first few weeks, antidepressant medications must be taken regularly for 3 to 4 weeks (in some cases, as many as 8 weeks) before the full therapeutic effect occurs.

Antidepressant drugs are not habit-forming. However, as is the case with any type of medication prescribed for more than a few days, antidepressants have to be carefully monitored to see if the correct dosage is being given. The doctor will check the dosage and its effectiveness regularly.

Anti-anxiety drugs or sedatives are not antidepressants. They are sometimes prescribed along with antidepressants; however, they are not effective when taken alone for a depressive disorder. Stimulants, such as amphetamines, are not effective antidepressants, but they are used occasionally under close supervision in medically ill depressed patients.