1. Phencyclidine [or other hallucinogen] is often taken in larger amounts or over a longer period than was intended.
2. There is a persistent desire or unsuccessful efforts to cut down or control phencyclidine (or other hallucinogen) use.
3. A great deal of time is spent in activities necessary to obtain phencyclidine (or other hallucinogen), use phencyclidine, or recover from its effects.
4. Craving, or a strong desire or urge to use phencyclidine (or other hallucinogen).
5. Recurrent phencyclidine (or other hallucinogen) use resulting in a failure to fulfill major role obligations at work, school, or home (e.g., repeated absences from work or poor performance related to phencyclidine use; phencyclidine-related absences, suspensions, or expulsions from school; or neglect of children or household).
6. Continued phencyclidine (or other hallucinogen) use despite having persistent or recurrent social or interpersonal problems caused or exacerbated by the effects of phencyclidine (e.g., arguments with a spouse about consequences of intoxication or physical fights).
7. Important social, occupational, or recreational activities are given up or reduced because of phencyclidine (or other hallucinogen) use.
8. Recurrent phencyclidine (or other hallucinogen) use in situations in which it is physically hazardous (e.g., driving an automobile or operating a machine when impaired by a phencyclidine).
9. Phencyclidine (or other hallucinogen) use is continued despite knowledge of having a persistent or recurrent physical or psychological problem that is likely to have been caused or exacerbated by phencyclidine.
10. Tolerance, as defined by either of the following:
    • a. A need for markedly increased amounts of phencyclidine to achieve intoxication or desired effect.
    • b. A markedly diminished effect with continued use of the same amount of phencyclidine.

PCP was initially made in 1926 and brought to market as an anesthetic medication in the 1950s. Its anesthetic effects were discovered by Victor Maddox, a chemist at Parke-Davis in Michigan, while investigating synthetic analgesic agents. It was approved for use as an investigational drug under the brand names Sernyl and Sernylan in the 1950s as an anesthetic, but because of its long terminal half-life and adverse side-effects, such as hallucinations, mania, delirium, and disorientation, it was removed from the market in 1965 and limited to veterinary use, until that was disallowed in 1978.

Treatment

There are no FDA-approved medications to treat addiction to hallucinogen addiction. While behavioral treatments can be helpful for patients with a variety of addictions, scientists need more research to find out if behavioral therapies are effective for addiction to hallucinogens. For HPDD, some antidepressant and antipsychotic medications can be used to improve mood and treat psychosis. Behavioral therapies can be used to help people cope with fear or confusion associated with visual disturbances. Management of PCP intoxication mostly consists of supportive care—controlling breathing, circulation, and body temperature—and, in the early stages, treating psychiatric symptoms. Benzodiazepines, such as lorazepam, are the drugs of choice to control agitation and seizures (when present).

Inhalant-Related Disorders

Inhalants are a broad range of household and industrial chemicals whose volatile vapors or pressurized gases can be concentrated and breathed in via the nose or mouth to produce intoxication in a manner not intended by the manufacturer. Inhalants are inhaled at room temperature through volatilization (in the case of gasoline or acetone) or from a pressurized container (e.g., nitrous oxide or butane), and do not include drugs that are sniffed after burning or heating. For example, amyl nitrite (poppers), nitrous oxide, and toluene—a solvent widely used in contact cement, permanent markers, and certain types of glue—are considered inhalants, but smoking tobacco, cannabis, and crack are not, even though these drugs are inhaled as smoke.

Figure 2. Even unintentional inhalant use can lead to inhalant intoxication marked by problematic behavioral or psychological changes.

While a small number of inhalants are prescribed by medical professionals and used for medical purposes, as in the case of inhaled anesthetics and nitrous oxide (an anxiolytic and pain relief agent prescribed by dentists), inhalants typically refer to the use of household and industrial propellants, glues, fuels, and other products in a manner not intended by the manufacturer to produce intoxication or other psychoactive effects. These products are used as recreational drugs for their intoxicating effect. According to a 1995 report by the National Institute on Drug Abuse, the most serious inhalant abuse occurs among homeless children and teens who “live on the streets completely without family ties.” Inhalants are the only substances used more by younger teens than by older teens. The practices are known colloquially as “sniffing”, “huffing,” or “bagging.”

Inhalant disorders described in the DSM-5 include inhalant use disorder, inhalant intoxication, other inhalant-induced disorders, and unspecified inhalant-related disorder. Inhalant use disorder is defined as a problematic pattern of use of a hydrocarbon-based inhalant substance leading to clinically significant impairment or distress.

Inhalant intoxication occurs frequently during inhalant use disorder but also may occur among individuals whose use does not meet the criteria for inhalant use disorder. Inhalant intoxication is identified as the following:

A. Recent intended or unintended short-term, high-dose exposure to inhalant substances, including volatile hydrocarbons such as toluene or gasoline.

B. Clinically significant problematic behavioral or psychological changes (e.g., belligerence, assaultiveness, apathy, and impaired judgment) that developed during, or shortly after, exposure to inhalants.

C. Two (or more) of the following signs or symptoms developing during, or shortly after, inhalant use or exposure:

• dizziness
• nystagmus
• incoordination
• slurred speech
• unsteady guilt
• lethargy
• depressed reflexes
• psychomotor retardation
• tremor
• generalized muscle weakness
• blurred vision or diplopia
• stupor or coma
• euphoria

The effects of inhalants range from an alcohol-like intoxication and intense euphoria to vivid hallucinations, depending on the substance and the dose. Some inhalant users are injured due to the harmful effects of the solvents or gases or due to other chemicals used in the products that they are inhaling. In some cases, users have died from hypoxia (lack of oxygen), pneumonia, cardiac failure or arrest, or aspiration of vomit. Brain damage is typically seen with chronic long-term use of solvents as opposed to short-term exposure.