Although antidepressants were originally developed for people suffering from medical depression, they are also quite effective at treating the symptoms of anxiety. To understand how antidepressants treat anxiety, consider that part of the brain is constantly releasing brain chemicals that act like messengers, called neurotransmitters. Neurotransmitters like serotonin, norepinephrine, and dopamine have been shown to have a calming, positive effect on mood. But after release, these chemicals have only a short time to do their job before they are reabsorbed by the brain. After this reabsorption, or reuptake, neurotransmitters cease to have any effect. In anxious people, this quick release and reuptake process may be the root of dizziness, racing heartbeat, and other panic symptoms. To counteract these symptoms, antidepressants decrease neurotransmitter reabsorption, in turn lessening anxiety symptoms. The newest antidepressants focus on limiting the reabsorption of anxiety-reducing serotonin in the brain. As such, they are called selective serotonin reuptake inhibitors, or SSRIs. SSRIs are most effective at treating certain types of anxiety disorders, like Obsessive-Compulsive Disorder, Post Traumatic Stress Disorder, social phobia, and Generalized Anxiety disorder. The most frequently prescribed SSRIs that have been FDA-approved to treat anxiety include: fluoxetine, which is branded as Prozac, Sertraline, or Zoloft and Paroxetine, which is known as Paxil. SSRIs have a close cousin in a type of antidepressants called serotonin-norepinephrine reuptake inhibitors, or SNRIs. Venlaxfaxine, or Effexor, is one SNRI helpful for treating the symptoms of Generalized Anxiety Disorder. Both SNRIs and SSRIs have few side effects and are among the most common medications prescribed for anxiety disorders. Another type of antidepressants, tricyclics, act to decrease reuptake of serotonin, norepinephrine, and dopamine. Imipramine, which is branded as Tofranil, is a tricyclic prescribed for both GAD and panic disorder and clomipramine, or Anafranil, is a tricylic used for treating OCD. Although the tricyclic antidepressants can be very effective at treating anxiety disorders, their side effects like weight gain, dizziness, and drowsiness may make them less desirable than SSRIs. Finally monoamine oxidase inhibitors, or MAOIs, are the oldest and final class of antidepressants. MAOIs also reduce reuptake of all three-mood neurotransmitters. MAOIs, like phenelzine, which is also known as Nardil, may be useful in treating panic disorder and social phobia. But because these medications can have serious side effects like increases in blood pressure and seizures, and severe reactions to certain foods like cheese, beans, wine and beer they are very infrequently used today. All antidepressants have no risk of addiction as compared with the benzodiazepine medications that are also used to treat anxiety disorders. The downside is that four to six weeks are required before a real reduction in symptoms is noticed. Antidepressants should always be taken under the direct supervision of a doctor, so talk to yours if you're concerned about anxiety.