Another class of antidepressant drug that is not as widely used is the monoamine oxidase inhibitors or MAOIs.  An amine is a chemical that is a derivative of ammonia and is normally a neurotransmitterSerotonin, norepinephrine and dopamine are all amines.  A monoamine is a single neurotransmitter.
Oxidase refers to enzymes that bring about oxidation.   Oxidation is the process of losing electrons from a molecule, atom or ion.  MAOIs act by preventing or slowing down the breakdown of serotonin, norepinephrine and even dopamine.  This increases their presence in the brain for a time and is the way that the drugs are supposed to alleviate depression.

MAOIs are known to cause adverse reactions with a number of foods and with SSRIs.  For example, people taking MAOIs can experience a sharp rise in their blood pressure that can rapidly lead to a stroke if they take decongestants or consume processed meat, fish, pickles, chocolate, alcoholic beverages, cheeses and soy sauce.

MAOIs can also have adverse reactions when combined with SSRIs.  As we have discussed, SSRIs work by inhibiting the reuptake of serotonin.  Since MAOIs slow and/or prevent the breakdown of serotonin, the combination of drugs can create high levels of serotonin and can cause serotonin syndrome which is discussed later.

The most common MAOIs are:

Generic Name

furazolidone
isocarboxazid
isoniazid
isoniazid rifampin
moclobemide
pargyline
phenelzine
procarbazine
selegiline
tranylcypromine

Trade Name

Furoxone®
Marplan®
Laniazid®, Nydrazid®
Rifamate®
Aurorix®, Manerix®
Eutonyl®
Nardil®
Matulane®
Atapryl®, Deprenyl®, Eldepryl®
Parnate®

SIDE EFFECTS
• Drowsiness
Anxiety
• Chills 
• Forgetfullness
• Hyperactivity
• Lethargy
• Sweating
• Palpitations
• Dry Mouth
• Constipation
• Nausea
Diarrhea
• Impotence
• Headache
Insomnia
• Tremors
• Dizziness
Paresthesia (tingling feelings in limbs)