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.

SSRIs

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).

SNRIs

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). 

Tricyclic Antidepressants 

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).

Benzodiazepines 

Since anxiety produces a lot of tension throughout the body, tranquilizers like benzodiazepines can help encourage a state of relaxation. They also begin to take effect in just a few minutes, which makes them useful for individuals to take on an as-needed basis or before an event that is likely to trigger an increase in anxiety. 

However, the brain tends to build a tolerance to benzodiazepines, which can make them less effective over time. This class of anti-anxiety medications can also lead to dependency, so most don't prescribe them for continuous use. Examples of benzodiazepines include alprazolam (Xanax), chlordiazepoxide (Librium), diazepam (Valium), and lorazepam (Ativan).

MAOIs

Monoamine oxidase inhibitors block the enzyme monoamine oxidase, which breaks down the critical mood-regulating chemicals serotonin, epinephrine, and dopamine. MAOIs help combat anxiety -- especially panic disorders and social phobias -- by preventing this enzyme from working, thus allowing more serotonin, epinephrine, and dopamine to remain in the brain.

Monoamine oxidase breaks down more than just the three neurotransmitters implicated in depression and anxiety, so inhibiting its function can lead to some side effects, including high blood pressure. Common MAOIs include isocarboxazid (Marplan), phenelzine (Nardil), selegiline (Emsam), and tranylcypromine (Parnate).

Beta-Blockers

Beta-blockers are meant for controlling high blood pressure and for treating certain heart conditions. Still, they can also relieve some of the physical symptoms of anxiety, thanks to the effect they have on norepinephrine. Beta-blockers include atenolol (Tenormin) and propranolol (Inderal).

Buspirone

Buspirone (BuSpar) is an anti-anxiety medicine that can treat both short-term (as-needed) anxiety symptoms and long-term anxiety disorders. Although it doesn't work as fast as benzodiazepines, it does not cause dependency and is associated with fewer side effects, though it's not useful for all types of anxiety.

Finding What Works for You

When you begin taking anti-anxiety medication, your doctor will check in with you frequently to determine the effectiveness of the prescription. They may need to adjust the dosage, prescribe additional medicine to complement the current one, or change course altogether. 

Finding what works for you may take time, but it's a worthwhile effort that can lead to a more fulfilling and satisfying life.