Experiencing occasional anxiety is a normal part of life. However, people with anxiety disorders frequently have intense, excessive and persistent worry and fear about everyday situations. Often, anxiety disorders involve repeated episodes of sudden feelings of intense anxiety and fear or terror that reach a peak within minutes (panic attacks).
These feelings of anxiety and panic interfere with daily activities, can last a long time, not to mention they are difficult to control and out of proportion to the actual danger. You may avoid places or situations to prevent these feelings. Symptoms may start during childhood or the teen years and continue into adulthood.
Examples of anxiety disorders include generalized anxiety disorder, social anxiety disorder (social phobia), specific phobias and separation anxiety disorder. You can have more than one anxiety disorder. Sometimes anxiety results from a medical condition that needs treatment. Whatever form of anxiety you have, treatment can help.

Symptoms

Common anxiety signs and symptoms include:

•     Feeling nervous, restless or tense

•     Having a sense of impending danger, panic or doom

•     Having an increased heart rate

•     Breathing rapidly (hyperventilation)

•     Sweating

•     Trembling

•     Feeling weak or tired

•     Trouble concentrating or thinking about anything other than the present worry

•     Having trouble sleeping

•     Experiencing gastrointestinal (GI) problems

•     Having difficulty controlling worry

•     Having the urge to avoid things that trigger anxiety

Several types of anxiety disorders exist

•     Agoraphobia

•     Anxiety disorder due to a medical condition

•     Generalized anxiety disorder

•     Panic disorder

•     Selective mutism

•     Separation anxiety disorder

•     Social anxiety disorder (social phobia)

•     Specific phobias

•     Substance-induced anxiety disorder

•     Other specified anxiety disorder and unspecified anxiety disorder

Causes

The causes of anxiety disorders aren't fully understood. Life experiences such as traumatic events appear to trigger anxiety disorders in people who are already prone to anxiety. Inherited traits also can be a factor.

Medical causes

Examples of medical problems that can be linked to anxiety include:

•     Heart disease

•     Diabetes

•     Thyroid problems, such as hyperthyroidism

•     Respiratory disorders, such as chronic obstructive pulmonary disease (COPD) and asthma

•     Drug misuse or withdrawal

•     Withdrawal from alcohol, anti-anxiety medications (benzodiazepines) or other medications

•     Chronic pain or irritable bowel syndrome

•     Rare tumors that produce certain fight-or-flight hormones

Sometimes anxiety can be a side effect of certain medications.
It's possible that your anxiety be due to an underlying medical condition if:

•     You don't have any blood relatives (such as a parent or sibling) with an anxiety disorder

•     You didn't have an anxiety disorder as a child

•     You don't avoid certain things or situations because of anxiety

•     You have a sudden occurrence of anxiety that seems unrelated to life events and you didn't have a previous history of anxiety

Risk factors

These factors may increase your risk of developing an anxiety disorder:

•     Trauma. Children who endured abuse or trauma or witnessed traumatic events are at higher risk of developing an anxiety disorder at some point in life. Adults who experience a traumatic event also can develop anxiety disorders.

•     Stress due to an illness. Having a health condition or serious illness can cause significant worry about issues such as your treatment and your future.

•     Stress buildup. A big event or a buildup of smaller stressful life situations may trigger excessive anxiety — for example, a death in the family, work stress or ongoing worry about finances.

•     Personality. People with certain personality types are more prone to anxiety disorders than others.

•     Other mental health disorders. People with other mental health disorders, such as depression, often also have an anxiety disorder.

•     Having blood relatives with an anxiety disorder. Anxiety disorders can run in families.

•     Drugs or alcohol. Drug or alcohol use or misuse or withdrawal can cause or worsen anxiety.

• Complications

Having an anxiety disorder does more than make you worry. It can also lead to, or worsen, other mental and physical conditions, such as:

•     Depression (which often occurs with an anxiety disorder) or other mental health disorders

•     Substance misuse

•     Trouble sleeping (insomnia)

•     Digestive or bowel problems

•     Headaches and chronic pain

•     Social isolation

•     Problems functioning at school or work

•     Poor quality of life

•     Suicide