clinically significant anxiety (e.g., generalized anxiety, panic attacks, phobic symptoms) caused by the direct physiological effects of exposure to a drug, toxin, or other substance. The anxiety symptoms may be associated with substance intoxication (e.g., alcohol, amphetamines, caffeine), substance withdrawal (e.g., alcohol, cocaine, sedatives), medication use (e.g., anesthetics, anticholinergics, thyroid medication), or exposure to heavy metals and toxins (e.g., gasoline, paint, carbon dioxide).