Function

• Most antidepressant medication works by adjusting certain neurotransmitters in the brain. Scientists still aren't sure exactly how the brain works, but the presence of specific biochemicals--particularly serotonin, but also other chemicals such as norepinphrine--play a large role in the elevation of mood. By increasing the levels of those neurotransmitters, antidepressants keep the patient's negative emotions in check.
  
  

SSRIs

• Selective serotonin reuptake inhibitors (SSRIs) represent the go-to treatment for many cases of depression. They focus specifically on serotonin levels in the brain, blocking its absorption and thus increasing its presence. The ranks of SSRI include Prozac, Paxil, Zoloft and Lexapro. Doctors prefer them because they have fewer side effects than other forms of antidepressants, although some patients report headaches, nausea, dry mouth, insomnia and/or impotence.
  
  

Tricyclic Antidepressants

• Tricyclic antidepressants were used for many years before SSRIs came along, and they are still used in cases where SSRIs are ineffective. They raise serotonin levels in the brain, as well as those of other neurotransmitters such as norepinphrine. Side effects tend to be more severe than those of SSRIs, including fatigue, constipation and difficulty concentrating. Their ranks include Tofranil, Norpramin and Evalil.
  
  

MAOIs

• Monoamine oxidase inhibitors (MAOIs) are prescribed if other forms of antidepressant medication fail. They work much the same way other medications do, but their side effects can be quite severe. Indeed, patients taking MAOIs are forbidden from ingesting certain kinds of food such as chicken, broccoli, cheese, sausage, raisins, bananas or any kind of alcohol as well as other antidepressants such as SSRIs. They can create harmful mixtures in the body when taken with the antidepressant, according to the Mayo Clinic.
  
  

Other Medications

• In some cases, a doctor may believe that something other than an antidepressant can help the patient cope with his depressive symptoms. For example, he may suggest a stimulant to elevate energy levels and stay focused, or antipsychotic medications if the depression is linked to a more serious mental condition. In every case, the patient should only take medication as prescribed by his doctor and never mix medications without careful consultation with a professional. He should always tell the doctor whether he is taking medication for a separate condition; it may interact badly with certain antidepressants and the doctor can alter his treatment plan accordingly.