Phencyclidine Use Disorder:
Symptoms, Side Effects and Treatment
Phencyclidine (PCP) use disorder represents a significant health concern in the United States, with its unique dissociative properties and potential for severe psychological and physical effects. According to the National Library of Medicine, approximately 2.5% of the U.S. population reports having used PCP at least once, with males accounting for about 75% of PCP-related emergency room visits.
The effects of this powerful hallucinogen can range from mild dissociative states to life-threatening medical emergencies, making understanding its use, effects, and treatment options critically important for healthcare providers and the public alike.
The impact of PCP use disorder extends beyond individual health consequences to affect families, communities, and healthcare systems. As a potent dissociative drug with unpredictable effects, PCP can lead to dangerous behaviors, psychosis, and significant medical complications that require emergency intervention and long-term treatment approaches.
What is Phencyclidine Use Disorder?
Phencyclidine use disorder is defined in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) as a pattern of problematic PCP use (or pharmacologically similar substances like ketamine) that leads to clinically significant impairment or distress. This disorder is characterized by a combination of cognitive, behavioral, and physiological symptoms indicating that an individual continues to use PCP despite significant substance-related problems.
To be diagnosed with phencyclidine use disorder, an individual must meet at least two of the following criteria within a 12-month period:
- Taking PCP in larger amounts or over a longer period than intended
- Persistent desire or unsuccessful efforts to cut down or control PCP use
- Spending considerable time obtaining, using, or recovering from PCP effects
- Craving or strong desire to use PCP
- Recurrent use resulting in failure to fulfill major role obligations
- Continued use despite persistent social or interpersonal problems
- Giving up important activities because of PCP use
- Recurrent use in physically hazardous situations
- Continued use despite knowledge of physical or psychological problems
- Tolerance (needing increased amounts for the same effect)
Unlike many other substance use disorders, phencyclidine use disorder does not include withdrawal as a diagnostic criterion, as withdrawal symptoms are not well-established in humans, though they have been reported in animal studies.
The severity of phencyclidine use disorder is classified as mild (2-3 symptoms), moderate (4-5 symptoms), or severe (6 or more symptoms). This spectrum reflects the progressive nature of the disorder, which often begins with experimental use and can develop into problematic use patterns over time.
Neurobiologically, PCP acts primarily as a non-competitive antagonist to the NMDA receptor, which causes analgesia, anesthesia, cognitive defects, and psychosis. PCP also blocks the uptake of dopamine and norepinephrine, leading to sympathomimetic effects such as hypertension, tachycardia, and agitation. These neurobiological mechanisms contribute to both the desired and adverse effects that characterize PCP intoxication and chronic use.
Common Forms of Phencyclidine and Related Substances
Phencyclidine and related substances come in various forms and are known by different street names:
- Phencyclidine (PCP): Originally developed as a general anesthetic in the 1950s, PCP appears as a crystalline powder that can be ingested orally, injected intravenously, inhaled, or smoked. Common street names include “angel dust,” “peace pill,” “hog,” “rocket fuel,” “embalming fluid,” “killer weed,” “love boat,” “ozone,” “super grass,” and “wack.” PCP was discontinued for human use in 1967 due to postoperative dysphoria and hallucinations but emerged as a popular street drug in the late 1960s and 1970s.
- Ketamine: A less potent PCP-like substance developed as a dissociative anesthetic, ketamine is commonly known as “K,” “Special K,” “vitamin K,” or “kitkat.” It can be used orally as a liquid or crystals, or administered intravenously. While it shares many properties with PCP, ketamine has a shorter duration of action and is currently used medically as an anesthetic and for treatment-resistant depression.
- Other PCP-like Substances: Cyclohexamine and dizocilpine are other substances with similar dissociative properties to PCP but are less commonly encountered in clinical settings.
These substances are typically administered in several ways:
- Inhaled through the nose (snorted)
- Injected into a vein
- Smoked (particularly when PCP is applied to leafy materials)
- Swallowed in pill form or mixed with food or drinks
The method of administration significantly affects the onset and intensity of effects. When injected or smoked, effects begin within 2-5 minutes, while oral ingestion typically produces effects within 30 minutes, peaking in 2-5 hours.
Development of Phencyclidine Use Disorder
The progression from initial PCP experimentation to problematic use typically follows a pattern that can be difficult to identify in its early stages. With continued exposure, physiological adaptations occur, leading to tolerance where users require escalating doses to experience the initial dissociative and euphoric effects. This adaptation is accompanied by changes in brain function that can persist long after discontinuation.
PCP is unique among substances of abuse in that its psychoactive effects can last for hours, but the total elimination time from the body typically takes 8 days or longer. This prolonged presence in the body contributes to the persistent and sometimes fluctuating symptoms observed in chronic users, as the drug can be released from lipid stores and adipose tissue days to months after initial use.
Risk Factors
While research on specific risk factors for PCP use disorder is limited compared to other substance use disorders, several factors appear to contribute to vulnerability:
- Gender: Males appear to be at higher risk, comprising approximately 75% of PCP-related emergency room visits.
- Age: Young adults between 18-34 years account for the majority of PCP-related emergency department visits, with 45% between 25-34 years old and 19% between 18-24 years old.
- Co-occurring mental health conditions: Individuals with pre-existing mental health disorders may be at increased risk of using PCP, possibly as a form of self-medication.
- Method of administration: Smoking or injecting PCP produces more rapid, intense effects than oral consumption, potentially accelerating the development of problematic use patterns.
- Polysubstance use: PCP is frequently used in combination with other substances, particularly marijuana, cocaine, analgesics, and anxiolytics, which can increase the risk of adverse effects and complicate treatment.
Phencyclidine Addiction Symptoms
Physical symptoms:
- Nystagmus (involuntary eye movements)
- Hypertension and tachycardia
- Altered body temperature
- Numbness and reduced pain sensitivity
- Loss of coordination
- Muscle rigidity
- Pupil changes (dilation or constriction)
- Irregular breathing patterns
Psychological symptoms:
- Feelings of detachment from reality
- Euphoria and reduced inhibition
- Delusions of mental clarity or strength
- Anxiety and paranoia
- Hallucinations (visual and auditory)
- Disorganized thinking
- Agitation and confusion
- Potential psychotic symptoms
Behavioral symptoms:
- Erratic, unpredictable behavior
- Social withdrawal
- Financial problems
- Neglect of responsibilities
- Continued use despite consequences
- Violent or aggressive actions
- Impaired work/school performance
- Engagement in risky behaviors
Health Impacts and Complications of Phencyclidine Abuse
Short-term Effects
The immediate effects of PCP use include dissociative states where users feel disconnected from their bodies and surroundings. Low to moderate doses cause numbness and loss of coordination, while larger doses may trigger extreme suspicion, auditory hallucinations, and aggressive or violent behavior.
PCP’s analgesic properties can mask pain from serious injuries, potentially leading to worsened outcomes as users may not seek medical attention. The drug’s effects on heart rate, blood pressure, breathing rate, and body temperature can fluctuate dramatically, with high doses potentially causing dangerous suppression of these vital functions.
Long-term Effects
Chronic PCP use can lead to severe and sometimes persistent health problems:
Neurological effects: Long-term PCP use can lead to memory loss, thinking problems, and speech difficulties such as slurring words or stuttering. Some of these cognitive effects may persist for months after cessation of use.
Psychological impact: Mood disorders such as depression and anxiety can develop with chronic use, potentially leading to suicidal ideation. The hallucinogenic effects may persist for weeks in some individuals, presenting as a psychotic episode resembling schizophrenia.
Physical deterioration: Rhabdomyolysis (breakdown of muscle tissue), kidney failure, cardiac arrhythmias, and seizures can occur with chronic use or high doses.
Risk of Overdose
PCP overdose can be life-threatening and is characterized by symptoms such as:
- Severe hypertension or hypotension
- Hyperthermia or hypothermia
- Cardiac arrhythmias
- Seizures
- Respiratory distress
- Muscle rigidity
- Coma
The risk of overdose is significantly increased with polysubstance use, particularly when PCP is combined with other central nervous system depressants or stimulants. A very large dose, especially when taken orally, may cause kidney failure, heart arrhythmias, muscle rigidity, seizures, or death.
Comorbidities in Phencyclidine Use Disorder
PCP use disorder frequently co-occurs with other mental health disorders. The drug’s effects can mimic symptoms of schizophrenia, making differential diagnosis challenging. Additionally, the persistent psychotic effects that can occur with PCP use may exacerbate underlying mental health conditions or trigger new onset of psychiatric symptoms.
For this reason, dual-diagnosis treatment – which addresses both substance use and co-occurring mental health issues simultaneously – is essential for effective, long-term recovery.
PCP Addiction Treatment Strategies
Effective PCP addiction treatment requires an integrated, evidence-based approach that addresses both the acute effects of intoxication and the longer-term challenges of recovery.
Medical Stabilization
The initial phase of treatment often focuses on managing the acute effects of PCP intoxication:
- Creating a calm, quiet environment with minimal stimulation
- Monitoring vital signs and providing supportive care
- Administering benzodiazepines for severe agitation, violent behavior, or psychosis
- Treating hyperthermia, hypertension, or seizures as needed
- Assessing and managing rhabdomyolysis or other medical complications
Unlike some other substances, there is no specific antidote or reversal agent for PCP intoxication. Treatment is primarily supportive, focusing on symptom management until the drug is eliminated from the body.
Psychotherapeutic Interventions:
Additional treatment options
Phencyclidine use disorder presents unique challenges due to the drug’s powerful dissociative properties, unpredictable effects, and potential for severe medical and psychiatric complications. While there are currently no FDA-approved medications specifically for PCP use disorder, a comprehensive approach that includes medical stabilization, psychotherapeutic interventions, and ongoing support can be effective in helping individuals achieve and maintain recovery.
Early intervention is crucial, as chronic use can lead to persistent cognitive deficits and psychiatric symptoms. Healthcare providers should be aware of the distinctive presentation of PCP intoxication, characterized by nystagmus, hypertension, and dissociative symptoms, to ensure appropriate diagnosis and treatment.
For individuals struggling with PCP use disorder, seeking specialized treatment represents the most reliable path to recovery. Modern addiction medicine recognizes this condition as a complex brain disorder requiring comprehensive intervention rather than simply a behavioral choice or character issue.
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