Definition: This block contains a wide variety of disorders that differ in severity and clinical form but that are all attributable to the use of one or more psychoactive substances, which may or may not have been medically prescribed. The third character of the code identifies the substance involved, and the fourth character specifies the clinical state. The codes should be used, as required, for each substance specified, but it should be noted that not all fourth character codes are applicable to all substances. Identification of the psychoactive substance should be based on as many sources of information as possible. These include self-report data, an ...[+++]alysis of blood and other body fluids, characteristic physical and psychological symptoms, clinical signs and behaviour, and other evidence such as a drug being in the patient's possession or reports from informed third parties. Many drug users take more than one type of psychoactive substance. The main diagnosis should be classified, whenever possible, according to the substance or class of substances that has caused or contributed most to the presenting clinical syndrome. Other diagnoses should be coded when other psychoactive substances have been taken in intoxicating amounts (common fourth character .0) or to the extent of causing harm (common fourth character .1), dependence (common fourth character .2) or other disorders (common fourth character .3-.9). Only in cases in which patterns of psychoactive substance-taking are chaotic and indiscriminate, or in which the contributions of different psychoactive substances are inextricably mixed, should the diagnosis of disorders resulting from multiple drug use (F19.-) be used. | Modifiers The following fourth-character subdivisions are for use with categories F10-F19: Code Title .0 Acute intoxication A condition that follows the administration of a psychoactive substance resulting in disturbances in level of consciousness, cognition, perception, affect or behaviour, o ...