Antidepressants are medications used to treat major depression and many other conditions (e.g., personality disorders, anxiety disorders). They appear to work by increasing the levels of the neurotransmitters (chemicals that convey nerve messages) serotonin, norepinephrine and dopamine in the brain. They are usually taken in pill form once or several times daily. However, extended-release and controlled-release versions are available for many antidepressants. These can be taken less frequently.

There are many classes of antidepressants. They include monoamine oxidase inhibitorsmonoamine oxidase inhibitors (MAOIs), tricyclic antidepressants (TCAs) and other serotonin-norepinephrine reuptake inhibitors (SNRIs) and selective serotonin reuptake inhibitors (SSRIs), among others. All antidepressants are about equally effective against depression, though different patients may respond better to one medication than another.

It typically takes two to three weeks to experience the effect of antidepressant medications. Initially, only side effects (e.g., nausea, drowsiness, weight gain) may occur. However, in most cases, the side effects, which vary according to the particular medication, improve or go away after about a week or two. Newer antidepressants have fewer side effects than older antidepressants.

When antidepressants are stopped suddenly, they may cause withdrawal symptoms, such as nausea, headache and dizziness.

It is generally recommended that patients refrain from consuming Alcoholwhile taking antidepressants. A number of other drugs may also interact poorly with antidepressant medications. Therefore, patients should notify their physician of all medications they are taking before starting a new antidepressant.

The safety of antidepressant use in pregnancy is not completely understood. The SSRI paroxetine appears to be more likely to be associated with birth defects.  Any woman taking antidepressants who is nursing, pregnant, or plans to become pregnant should discuss the medication with an obstetrician.

The SSRI fluoxetine is the only antidepressant that has been approved for use in children. However, close monitoring of any children on antidepressants is recommended due to potentially increased risk of suicidal thoughts and behavior in children taking these medications. Antidepressants generally work as effectively in elderly patients as in younger adults.