The Anxiety and Depression Association of America (ADAA) recognizes four major classes of drugs for treating anxiety disorders: SSRIs, SNRIs, tricyclic antidepressants, and benzodiazepines. Other medications prescribed for anxiety may include MAOIs, beta-blockers, and buspirone.
Selective serotonin reuptake inhibitors, or SSRIs, block nerve cells in the brain from reabsorbing serotonin. Therefore, the brain's supply of serotonin -- an important mood regulator -- lasts longer and decreases symptoms of anxiety. One drawback of SSRIs is that they take effect over two to six weeks of regular use, and they don't work for everyone. However, they do not pose a risk of dependency. Types of SSRIs include citalopram (Celexa), escitalopram (Lexapro), fluoxetine (Prozac), and sertraline (Zoloft).
Serotonin-norepinephrine reuptake inhibitors work like SSRIs, but instead of blocking the reabsorption of serotonin only, SNRIs also block the reuptake of another mood-regulating chemical called norepinephrine. Examples of SNRIs include duloxetine (Cymbalta) and venlafaxine (Effexor).
Like SSRIs and SNRIs, tricyclic antidepressants are useful in treating anxiety because they prevent nerves in the brain from absorbing too much serotonin and norepinephrine. Tricyclic antidepressants are associated with numerous side effects, including withdrawal when you stop using them.
They are contraindicated with seizure disorders and an option only to select patients for whom SSRIs or SNRIs prove ineffective. Examples of tricyclic antidepressants include amitriptyline (Elavil), imipramine (Tofranil), and nortriptyline (Pramalor).