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Overview of Anxiety Disorders


John W. Barnhill

, MD, Weill Cornell Medical College and New York Presbyterian Hospital

Last full review/revision Apr 2020| Content last modified Apr 2020

Anxiety is a feeling of nervousness, worry, or unease that is a normal human experience. It is also present in a wide range of psychiatric disorders, including generalized anxiety disorder, panic disorder, and phobias. Although each of these disorders is different, they all feature distress and dysfunction specifically related to anxiety and fear.

  • In addition to anxiety, people often also have physical symptoms, including shortness of breath, dizziness, sweating, rapid heartbeat, and/or tremor.
  • Anxiety disorders often substantially change people's daily behavior, including leading them to avoid certain things and situations.
  • These disorders are diagnosed using specific established criteria.
  • Drugs, psychotherapy, or both can substantially help most people.

Anxiety is a normal response to a threat or to psychologic stress. Normal anxiety has its root in fear and serves an important survival function. When someone is faced with a dangerous situation, anxiety triggers the fight-or-flight response. With this response, a variety of physical changes, such as increased blood flow to the heart and muscles, provide the body with the necessary energy and strength to deal with life-threatening situations, such as running from an aggressive animal or fighting off an attacker.

However, anxiety is considered a disorder when it

  • Occurs at inappropriate times
  • Occurs frequently
  • Is so intense and long-lasting that it interferes with a person's normal activities

Anxiety disorders are more common than any other category of mental health disorder and affect about 15% of adults in the United States. Significant anxiety can persist for years and begin to feel normal to the person with the anxiety. For this and other reasons, anxiety disorders are often not diagnosed or treated.

Anxiety disorders include

The mental distress that occurs immediately or shortly after experiencing or witnessing an overwhelming traumatic event is no longer classified as an anxiety disorder. Such disorders are now classified as Overview of Trauma- and Stress-Related Disorders and include Acute Stress Disorder, Adjustment Disorder, and Posttraumatic Stress Disorder (PTSD).

How Anxiety Affects Performance

The effects of anxiety on performance can be shown on a curve. As the level of anxiety increases, performance efficiency increases proportionately, but only up to a point. As anxiety increases further, performance efficiency decreases. Before the peak of the curve, anxiety is considered adaptive because it helps people prepare for a crisis and improve their functioning. Beyond the peak of the curve, anxiety is considered maladaptive because it produces distress and impairs functioning.

How Anxiety Affects Performance

Causes of Anxiety Disorders

The causes of anxiety disorders are not fully known, but the following may be involved:

  • Genetic factors (including a family history of an anxiety disorder)
  • Environment (such as experiencing a traumatic event or stress)
  • Psychologic makeup
  • A physical condition

An anxiety disorder can be triggered by environmental stresses, such as the breakup of a significant relationship or exposure to a life-threatening disaster.

When a person's response to stresses is inappropriate or a person is overwhelmed by events, an anxiety disorder can arise. For example, some people find speaking before a group exhilarating. But others dread it, becoming anxious with symptoms such as sweating, fear, a rapid heart rate, and tremor. Such people may avoid speaking even in a small group.

Anxiety tends to run in families. Doctors think some of this tendency may be inherited, but some is probably learned by living with anxious people.

Did You Know...

  • Anxiety disorders are the most common type of mental health disorder.
  • People with an anxiety disorder are more likely than other people to have depression.

Anxiety caused by a physical disorder or drug

Anxiety can also be caused by a general medical disorder or the use or discontinuation (withdrawal) of a drug. General medical disorders that can cause anxiety include the following:

Even fever can cause anxiety.

Anxiety may occur in dying people as a result of fear of death, pain, and difficulty breathing (see Symptoms During a Fatal Illness : Depression and Anxiety).

Drugs that can trigger anxiety include the following:

  • Alcohol
  • Stimulants (such as amphetamines)
  • Caffeine
  • Cocaine
  • Many prescription drugs, such as corticosteroids
  • Some over-the-counter weight-loss products, such as those containing the herbal product guarana, caffeine, or both

Withdrawal from alcohol or sedatives, such as benzodiazepines (used to treat anxiety disorders; see the appropriate entry in the table Drugs Used to Treat Anxiety Disorders), can cause anxiety and other symptoms, such as insomnia and restlessness.

Symptoms of Anxiety Disorders

Anxiety can arise suddenly, as in panic, or gradually over minutes, hours, or days. Anxiety can last for any length of time, from a few seconds to years. It ranges in intensity from barely noticeable qualms to a full-blown panic attack, which may cause shortness of breath, dizziness, an increased heart rate, and trembling (tremor).

Anxiety disorders can be so distressing and interfere so much with a person's life that they can lead to depression. People may develop a substance use disorder. People who have an anxiety disorder (except for certain very specific phobias, such as fear of spiders) are at least twice as likely to have depression as those without an anxiety disorder. Sometimes people with depression develop an anxiety disorder.

Diagnosis of Anxiety Disorders

  • A doctor's evaluation, based on specific criteria

Deciding when anxiety is severe enough to be considered a disorder can be complicated. People's ability to tolerate anxiety varies, and determining what constitutes abnormal anxiety can be difficult. Doctors usually use the following specific established criteria:

  • Anxiety is very distressing.
  • Anxiety interferes with functioning.
  • Anxiety is long-lasting or keeps coming back.

Doctors look for other disorders that may be causing anxiety, such as depression or a sleep disturbance. Doctors also ask whether relatives have had similar symptoms, because anxiety disorders tend to run in families.

Doctors also do a physical examination. Blood and other tests may be done to check for other medical disorders that can cause anxiety.

Treatment of Anxiety Disorders

  • Treatment of the cause if appropriate
  • Psychotherapy
  • Drug therapy
  • Treament of other active disorders

Accurate diagnosis is important because treatment varies from one anxiety disorder to another. Additionally, anxiety disorders must be distinguished from anxiety that occurs in many other mental health disorders, which involve different treatment approaches.

If the cause is another medical disorder or a drug, doctors aim to correct the cause rather than treat the symptoms of anxiety. Anxiety should subside after the physical disorder is treated or the drug has been stopped long enough for any withdrawal symptoms to abate. If anxiety remains, antianxiety drugs or psychotherapy (such as behavioral therapy) is used.

For people who are dying, certain strong pain relievers, such as morphine, may relieve both pain and anxiety.

If an anxiety disorder is diagnosed, drug therapy or psychotherapy (such as behavioral therapy), alone or in combination, can significantly relieve the distress and dysfunction for most people. Benzodiazepines (such as diazepam) are commonly prescribed for acute anxiety. For many people, antidepressants, such as selective serotonin reuptake inhibitors (SSRIs), work as well for anxiety disorders as they do for depression. Specific treatments depend on which anxiety disorder is diagnosed.

All of the anxiety disorders can occur along with other psychiatric conditions. For example, anxiety disorders often occur along with an alcohol use disorder. It is important to treat all of these conditions as soon as possible. Treating the alcohol use disorder without treating the anxiety is unlikely to be effective since the person may be using alcohol to treat the anxiety. On the other hand, treating the anxiety without addressing the alcohol disorder may be unsuccessful because daily changes in the amount of alcohol in the blood can cause levels of anxiety to fluctuate.

Drugs Used to Treat Anxiety Disorders



Some Side Effects










Generalized anxiety disorder

Panic disorder

Phobic disorders

Sleepiness, memory problems, impaired coordination, and slowed reaction time

May lead to drug dependence

Most commonly used type of antianxiety drug

Promote mental and physical relaxation by reducing nerve activity in the brain

Begin to work quickly, sometimes within an hour

Should not be used by people with an alcohol use disorder


Generalized anxiety disorder

Dizziness and headache

Does not cause drowsiness or interact with alcohol

Does not lead to drug dependence

May take several weeks to start working


SSRIs (such as escitalopram)

SNRIs (such as venlafaxine)


TCAs (such as clomipramine)

Generalized anxiety disorder

Panic disorder

Phobic disorders

Posttraumatic stress disorder

See table Drugs Used to Treat Depression

See table Drugs Used to Treat Depression

* Not all of the antidepressants listed work for all of the uses that are listed.

MAOI = monoamine oxidase inhibitor; SNRI = selective norepinephrine reuptake inhibitor; SSRI = selective serotonin reuptake inhibitor; TCA = tricyclic antidepressant.

More Information about Anxiety Disorders

  • National Institute of Mental Health, Anxiety Disorders: General information on many aspects of all the anxiety disorders, including crisis lines and educational programs

Drugs Mentioned In This Article

Generic Name Select Brand Names
Chlordiazepoxide LIBRIUM
escitalopram LEXAPRO
clomipramine ANAFRANIL
Clorazepate TRANXENE
venlafaxine EFFEXOR XR
Alprazolam XANAX
Clonazepam KLONOPIN
Buspirone No US brand name
Lorazepam ATIVAN
diazepam VALIUM

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