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:

• Heart disorders, such as:
  • Heart failure; and
  • Abnormal heart rhythms (arrhythmias)
• Hormonal (endocrine) disorders, such as:
  • An overactive adrenal gland (hyperadrenocorticism); or
  • Thyroid gland (hyperthyroidism); or
  • A hormone-secreting tumour called a pheochromocytoma.
• Lung (respiratory) disorders, such as:
  • Asthma; and
  • Chronic obstructive pulmonary disease (COPD).

Even fever can cause anxiety.

Anxiety may occur in dying people as a result of fear of death, pain, and difficulty breathing.

Drugs that can trigger anxiety include the following:

• Alcohol;
• Stimulants (such as amphetamines);
• Caffeine;
• Cocaine;
• Many prescription drugs, such as corticosteroids; and
• 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), can cause anxiety and other symptoms, such as insomnia and restlessness.