According to the American Psychiatric Association’s guidelines, people with substance intoxication delirium have classic symptoms of delirium that clearly stem from the use of alcohol, medications or drugs, or from unintentional exposure to delirium-inducing toxic chemicals. In order to qualify as a mental disorder, the symptoms of delirium must cause greater mental disruption than the forms of disruption normally associated with the use of the substance in question. In addition, the amount of mental disruption present in an affected individual must be great enough to require some form of medical intervention.
In addition to alcohol, types of substances officially classified as unique potential causes of substance intoxication delirium include phencyclidine (PCP), drugs related to phencyclidine, amphetamine,drugs related to amphetamine, legal and illegal narcotics (opioids), inhalants, sedative medications, hallucinogens, cocaine, anti-anxiety medications, marijuana and hashish (cannabis), and soporific (sleep-producing) medications. All other substances capable of producing the condition-including Parkinson’s disease medications, digoxin (digitalis), and medications called histamine H2-receptor antagonists-belong to an undifferentiated category referred to as “other or unknown substances.”