Substance/Medication-Induced Anxiety Disorder

Substance/medication-induced anxiety disorder is diagnosed after an individual uses a substance (e.g., a drug of abuse, a medication, or a toxin exposure) that leads to prominent symptoms of panic or anxiety.

• The estimated 12-month prevalence is 0.002%, but its prevalence is likely much, much higher.^[1]

Panic attacks or anxiety is predominant in the clinical picture.

There is evidence from the history, physical examination, or laboratory findings of both (1) and (2):

1. The symptoms in Criterion A developed during or soon after substance intoxication or withdrawal or after exposure to a medication
2. The involved substance/medication is capable of producing the symptoms in Criterion A

The disturbance is not better explained by an anxiety disorder that is not substance/medication-induced. Such evidence of an independent anxiety disorder could include the following:

• The symptoms precede the onset of the substance/medication use; the symptoms persist for a substantial period of time (e.g. - about 1 month) after the cessation of acute withdrawal or severe intoxication: or there is other evidence suggesting the existence of an independent non-substance/medication-induced anxiety disorder (e.g. - a history of recurrent non-substance/medication-related episodes).

The disturbance does not occur exclusively during the course of a delirium.

The disturbance causes clinically significant distress or impairment in social, occupational, or other important areas of functioning.

• Panic or anxiety can occur in association with intoxication with the following substances:
  • Alcohol, caffeine, cannabis, phencyclidine, other hallucinogens, inhalants, and stimulants.
• Panic or anxiety can occur in association with withdrawal from the following classes of substances:
  • Alcohol, opioids, sedatives, hypnotics, anxiolytics, stimulants (including cocaine)
• Medications that can cause anxiety symptoms include:
  • Anesthetics, analgesics, sympathomimetics, bronchodilators (e.g. - theophylline), anticholinergics, insulin, thyroid replacement, oral contraceptives, antihistamines, antiparkinsonian medications, corticosteroids, antihypertensives, cardiovascular medications, anticonvulsants, lithium, antipsychotics, and antidepressants.
• Heavy metals and toxins can also cause panic or anxiety symptoms, including:
  • Oganophosphate insecticide, nerve gases, carbon monoxide, carbon dioxide, and volatile substances (e.g. - gasoline, paint)

• Substance intoxication and substance withdrawal
  • Anxiety symptoms are common in substance intoxication and substance withdrawal. For example, panic or anxiety symptoms are characteristic of alcohol withdrawal.
• Anxiety disorder (i.e. - not induced by a substance/medication)
  • Substance/medication-induced anxiety disorder is different from a primary anxiety disorder based on the onset, course, and other factors with respect to substances/medications.
  • For drugs of abuse, there must be evidence from the history, physical examination, or laboratory findings for use, intoxication, or withdrawal.
  • A primary anxiety disorder diagnosis is warranted if the panic or anxiety symptoms persist for a substantial period of time (about 1 month or longer) after the end of the substance intoxication or acute withdrawal or there is a history of an anxiety disorder.
• Anxiety disorder due to another medical condition
  • Features atypical of a primary anxiety disorder, such as unsual age at onset (e.g. - onset of panic disorder after age 45 years) or symptoms (e.g. - atypical panic attack symptoms such as true vertigo, loss of balance, loss of consciousness, loss of bladder control, headaches, slurred speech) may suggest a medical etiology.
• Delirium
  • If panic or anxiety symptoms occur exclusively during the course of delirium, they are a feature of the delirium.
• Anxiety disorder due to another medical condition
  • If the panic or anxiety symptoms are attributed to the physiological consequences of another medical condition (i.e. - rather than to the medication taken for the medical condition), anxiety disorder due to another medical condition should be diagnosed. The history often provides the basis for such a judgment. At times, a change in the treatment for the other medical condition (e.g. - medication substitution or discontinuation) may be needed to determine whether the medication is the causative agent.

• Depending on the initial presenting symptoms (e.g. - dizziness, tachycardia), potential investigations can include: CBC, fasting glucose, fasting lipid profiles, electrolytes, liver enzymes, serum bilirubin, serum creatinine, urinalysis, urine toxicology for substance use, thyroid stimulating hormone (TSH).^[2]
• Urine toxicology should also be done if warranted.^[3]
• An ECG and beta-HCG should be ordered if relevant.