+2 more
Tic Tac, Zoomketamine, dextromethorphan, MK-801 +1 moreketamine, dextromethorphan, MK-801, methoxetamine show less
PCP
phencyclidine
PCP (phencyclidine) — Angel Dust, Wet, Sherman — is a synthetic dissociative of the arylcyclohexylamine class. It is the parent compound of the arylcyclohexylamine family, from which ketamine and its analogues descend. It blocks glutamate signaling while amplifying dopamine activity, producing dissociation and a distinctly psychosis-like experience.[1]
PCP (phencyclidine) — Angel Dust, Wet, Sherman — is a synthetic dissociative of the arylcyclohexylamine class. It is the parent compound of the arylcyclohexylamine family, from which ketamine and its analogues descend. PCP is a noncompetitive NMDA receptor antagonist with secondary activity at dopamine D2 receptors,[1] producing its effects by blocking glutamate signalling while amplifying dopamine activity.
+2 more
Tic Tac, Zoomketamine, dextromethorphan, MK-801 +1 moreketamine, dextromethorphan, MK-801, methoxetamine show less
Harold Maddox synthesised PCP at Parke-Davis in 1956 and briefly marketed it as the surgical anaesthetic Sernyl.[2][3] Severe post-operative psychosis led to its withdrawal from human use in 1965, and it became a major street drug through the 1970s.[2][4] PCP has no approved medical use today and remains Schedule II in the United States.
Subjective effects include dissociation, analgesia, paranoid thoughts, hallucinations, amnesia, and loss of motor coordination. The experience is more agitated and reality-fracturing than Ketamine, with detachment coexisting alongside hostile arousal rather than tranquil withdrawal. Amnesia, prolonged psychotic episodes, and extreme agitation are characteristic unwanted effects.
PCP produces dopamine-driven reinforcement and carries a narrow margin between recreational and dangerous doses.[5][6] It accumulates in fat tissue and redistributes unpredictably, with muscle breakdown occurring in roughly 70% of clinical poisoning cases.[6] Decades of clinical toxicology data inform current understanding, but human tolerance, withdrawal, and lethal dose remain incompletely characterised.[7]
History[edit]
Discovery
Harold Maddox synthesised phencyclidine at Parke-Davis on 26 March 1956.[3] Animal testing revealed an unusual profile that defied existing anaesthetic categories: rodents appeared intoxicated while pigeons entered cataleptic stillness.[3][2] Human trials confirmed effective surgical anaesthesia, and Parke-Davis marketed it as Sernyl around 1963.[3]
Clinical withdrawal and scientific legacy
Many surgical patients developed severe post-operative delirium and frank psychosis unlike anything seen with other anaesthetics, leading to withdrawal from human use in 1965.[2][3] Veterinary use continued as Sernylan until 1978.[2] In 1983, David Lodge and colleagues identified PCP and ketamine as NMDA blockers, launching the NMDA hypofunction hypothesis of schizophrenia.[2]
Prohibition and street drug era
PCP appeared on the illicit market in the late 1960s as "The PeaCe Pill" and became a major drug of abuse through the 1970s, distributed as tablets, powder, and liquid applied to plant material for smoking.[4] Use peaked around 1979 at approximately 14% lifetime exposure among US high school seniors.[4] PCP was upgraded to Schedule II as the epidemic grew and placed in Schedule I of the 1971 UN Convention on Psychotropic Substances.[4][7]
The name "phencyclidine" comes from its chemical components: phenyl + cyclohex + piperidine. Street names from the 1970s epidemic included Angel Dust, Sherman, Wet, Boat, and Zoom, with regional variations reflecting local distribution networks. "Wet" and "Boat" refer to the practice of dipping cigarettes or joints in liquid PCP, the predominant street route. PCP's reputation for superhuman strength is largely exaggerated: dissociative anaesthesia removes pain as a limiter rather than enhancing muscular capacity.
Chemistry[edit]
Structural class
Phencyclidine is the founding member of the arylcyclohexylamine family — the same structural class as ketamine, methoxetamine, and the designer analogues 3-MeO-PCP and 4-MeO-PCP.[8] Its molecular formula is C₁₇H₂₅N (molecular weight 243.4 g/mol).
PCP occupies the simplest position in the family: an unsubstituted phenyl ring, unsubstituted cyclohexane, and a piperidine as the nitrogen component.
Pharmacology[edit]
Mechanism of action
PCP lodges inside an open glutamate channel and physically blocks ion flow, suppressing neural circuits in proportion to how active they are.[2] High-resolution imaging has confirmed this position inside the channel pore.[9] It also binds dopamine receptors[1] and blocks dopamine reuptake,[10] producing additional dopamine activation that deepens its psychosis-like effects.
PCP was historically described as a kappa opioid receptor agonist. Modern pharmacological reviews do not support this as a primary mechanism.[11][2][4] Naloxone does not block PCP's effects in humans, and the original attribution arose from early studies that could not distinguish between different binding sites.
Pharmacokinetics
PCP absorbs well orally, with about 72% reaching the bloodstream.[12][13] Onset is 2–5 minutes when smoked or injected and 20–60 minutes when swallowed.[4][6] Primary effects last 4–8 hours, though psychosis can persist for days to weeks after high doses.[4][7]
PCP accumulates extensively in fat and brain tissue.[4] It can redistribute from tissue stores days after last use, causing symptoms to recur without any further dosing.[6] The half-life averages 17–21 hours but varies widely between individuals.[12]
Neuroscience[edit]
Where it acts
PCP blocks glutamate channels on inhibitory neurons in the cortex and limbic system.[14] When these inhibitory neurons go quiet, the excitatory neurons they normally restrain become overactive, flooding downstream circuits with glutamate. The result is paradoxical: a drug that blocks glutamate receptors ultimately produces excess glutamate activity in cortical output pathways.
Why it matters
That glutamate overactivation drives elevated dopamine release in the prefrontal cortex and striatum,[14] on top of PCP's direct dopamine receptor binding[1] and its block on dopamine reuptake.[10] The combined dopamine activation exceeds what any single mechanism would produce.
PCP is the only drug that reliably reproduces both the positive symptoms of schizophrenia (paranoia, hallucinations) and the negative symptoms (emotional withdrawal, cognitive slowing) in healthy volunteers.[15][11] Chronic exposure produces the opposite of simple tolerance: the brain upregulates glutamate receptors, and each re-exposure produces a stronger response.[16]
PCP can produce psychotic states lasting days to weeks,[7] far beyond its measured half-life even accounting for fat redistribution. Whether this reflects sustained circuit disruption, slow receptor unbinding, or active metabolite contributions is unknown. The relative contribution of glutamate blockade versus direct dopamine receptor binding[1] to psychotomimetic effects at human plasma concentrations remains debated.
Subjective Effects[edit]
PCP's dissociation is externalised, not introspective. Rather than drawing inward into dreamlike detachment, the experience fractures outward: thoughts break apart, paranoid ideation floods in, and the body disconnects from pain while remaining capable of hostile agitation. Set and setting exert far less moderating influence than with serotonergic psychedelics.
Compared to ketamine, PCP is substantially more potent, lasts several times longer, and carries far greater risk of prolonged psychosis.[7] Compared to dextromethorphan, PCP's profile is dominated by psychosis-like agitation rather than by sedation.
Synthesised by Harold Maddox at Parke-Davis in 1956, PCP was briefly marketed as the surgical anaesthetic Sernyl before severe post-operative psychosis led to its withdrawal from human use in 1965.[2] It became a major street drug through the 1970s, peaking at 14% lifetime use among US high school seniors by 1979.[3] PCP remains Schedule II in the United States with no approved medical use, and provided the pharmacological foundation for the NMDA hypofunction hypothesis of schizophrenia.[4]
Subjective effects include dissociation, analgesia, depersonalisation, thought disorder, paranoid ideation, and motor incoordination. The experience is distinctly externalised and psychotomimetic — less dreamlike than Ketamine, more agitated and reality-fracturing, with detachment that coexists with hostile arousal rather than tranquil withdrawal. Amnesia, severe agitation, and prolonged psychotic episodes are characteristic unsought effects.
PCP produces dopaminergic reinforcement confirmed in animal models,[5] and carries a narrow margin between recreational and life-threatening doses.[6] Extreme lipophilicity drives tissue accumulation and unpredictable redistribution, while chronic exposure produces NMDA receptor upregulation and behavioural sensitisation rather than simple tolerance[7] — and muscle breakdown occurs in roughly 70% of clinical poisoning cases.[6] Decades of clinical toxicology data inform the current understanding, though human tolerance, withdrawal, and lethal dose remain incompletely characterised.[8]
History[edit]
Discovery
Harold Maddox synthesised phencyclidine (CI-395) at Parke-Davis on 26 March 1956.[9] Animal testing revealed an unusual profile — rodents appeared intoxicated while pigeons entered cataleptic immobility — that defied existing anaesthetic categories.[9][2] Human trials at Detroit Receiving Hospital confirmed effective surgical anaesthesia with minimal respiratory depression, and Parke-Davis marketed the compound as Sernyl around 1963.[9]
Clinical withdrawal and scientific legacy
A significant proportion of surgical patients developed severe emergence reactions — prolonged dysphoria, delirium, and frank psychosis unlike anything seen with other anaesthetics — leading to withdrawal from human clinical use in 1965.[2][9] Veterinary use continued under the name Sernylan until 1978.[2] The decisive scientific advance came in 1983, when David Lodge and colleagues identified PCP and ketamine as noncompetitive NMDA receptor antagonists — linking dissociative pharmacology to the glutamate system and launching the NMDA hypofunction hypothesis of schizophrenia.[2]
Prohibition and street drug era
PCP appeared on the illicit market in the late 1960s as "The PeaCe Pill" and became a major drug of abuse through the 1970s, distributed as tablets, powder, and — most characteristically — as liquid applied to plant material for smoking.[3] Use peaked around 1979 at approximately 14% lifetime exposure among US high school seniors.[3] Initially placed on Schedule III in 1970, PCP was upgraded to Schedule II as the epidemic grew,[3][8] and was placed in Schedule I of the 1971 UN Convention on Psychotropic Substances.
The name "phencyclidine" derives from its chemical components: phenyl + cyclohex + piperidine. Street nomenclature proliferated during the 1970s epidemic — Angel Dust, Sherman, Wet, Boat, Zoom — with regional variations reflecting local distribution networks. "Wet" and "Boat" refer specifically to the practice of dipping cigarettes or joints in liquid PCP, the predominant mode of street use.
Chemistry[edit]
Structural class
Phencyclidine is the prototypical arylcyclohexylamine — a structural family defined by an aryl group bonded to a cyclohexane ring bearing an amine substituent. This scaffold is shared by ketamine, methoxetamine, and the designer PCP analogues (3-MeO-PCP, 4-MeO-PCP).[10] PCP occupies the simplest position in the series: an unsubstituted phenyl ring, unsubstituted cyclohexane, and the six-membered piperidine as the amine component.
Molecular structure
| Molecular formula | C₁₇H₂₅N |
| Molecular weight | 243.4 g/mol |
The molecule consists of a cyclohexane ring bearing a phenyl group and a piperidine nitrogen at the same carbon. The single nitrogen atom serves as the basic centre (pKa ~8.29), making PCP a weak base substantially ionised at physiological pH. The compound's extensive hydrocarbon surface gives it pronounced lipophilicity — the dominant factor in its pharmacokinetic behaviour, driving tissue accumulation and prolonged effects.
Stereochemistry
PCP is achiral. Although the C1 carbon of the cyclohexane ring bears four substituent attachment points, the ring's symmetry means this centre does not constitute a true stereocenter. This contrasts with Ketamine, where the equivalent carbon generates R- and S-enantiomers with distinct pharmacological profiles.
Physical properties
The free base is an oily liquid at room temperature with high lipid solubility. The hydrochloride salt is a white crystalline powder — the form most commonly encountered in forensic analysis. PCP base is volatile enough to be smoked effectively, a property exploited in the predominant street route of administration.
When smoked, pyrolysis generates phenylcyclohexene (PC), a decomposition product that retains pharmacological activity at lower potency.[11]
Pharmacology[edit]
Mechanism of action
PCP acts as a noncompetitive, open-channel blocker at the NMDA — the primary mechanism driving its dissociative, amnestic, and psychotomimetic effects.[2] The compound lodges within the ion channel pore when the channel is open, physically preventing ion flow. This use-dependent block means PCP's inhibitory effect increases with glutamatergic activity — the more active a neural circuit, the more effectively PCP suppresses it.
High-resolution structural imaging has directly visualised PCP within the NMDA channel pore, confirming its position among pore-lining residues.[12] Among NMDA channel blockers, PCP is more potent than ketamine and dextromethorphan but less potent than MK-801.[13]
Beyond NMDA antagonism, PCP binds with high affinity to the D2 receptor in its active state.[1] This dual glutamatergic-dopaminergic action — NMDA blockade combined with D2 activation — distinguishes PCP from most other dissociatives and likely underlies its pronounced psychotomimetic character.
PCP also inhibits dopamine reuptake, demonstrated in primate brain imaging studies.[14] The convergence of NMDA antagonism, D2 binding, and DAT inhibition produces a three-pronged dopaminergic activation that no single mechanism would predict.
PCP is historically cited as a kappa opioid receptor agonist. Modern pharmacological reviews do not support this as a primary mechanism.[15][2][3] The attribution likely arose from early studies using radioligands that could not distinguish between opioid, sigma, and PCP binding sites. Naloxone does not block PCP's effects in humans.
Pharmacokinetics
PCP is well absorbed orally, with approximately 72% reaching the bloodstream.[16][17] Onset varies by route: 2–5 minutes when smoked or injected, and 20–60 minutes when swallowed, with peak blood levels at roughly 90 minutes after oral ingestion.[3][6]
Primary intoxication lasts 4–8 hours at typical doses,[3] though symptoms can persist up to 48 hours in overdose[6] and psychosis can last days to weeks after high-dose exposure.[8] The half-life averages 17–21 hours but ranges from 7 to 46 hours between individuals.[16]
PCP's high lipophilicity drives extensive tissue accumulation, particularly in fat and brain tissue. Cerebrospinal fluid concentrations reach 6–9 times blood levels.[3] This fat-depot effect is clinically important: the drug can redistribute from tissue stores and produce recurrent symptoms days after last use.[6]
The liver breaks down PCP primarily through hydroxylation of the cyclohexane and piperidine rings, with roughly 73% of the dose eliminated through the kidneys as the drug and its metabolites.[16][17] When smoked, heat converts a portion of PCP to phenylcyclohexene, which retains some activity at lower potency.[11] Female rats show longer half-life and greater sensitivity to PCP's effects than males,[18] though equivalent human sex-difference data are not available.
Neuroscience[edit]
Where it acts
PCP's NMDA blockade preferentially silences inhibitory interneurons in cortical and limbic circuits — neurons that depend heavily on NMDA-mediated drive for their tonic activity.[19] When these interneurons go quiet, the excitatory neurons they normally restrain become disinhibited, flooding downstream circuits with glutamate. The result is paradoxical: a drug that blocks glutamate receptors ultimately produces a hyperglutamatergic state in cortical output pathways.
This glutamate surge drives increased dopamine release in the prefrontal cortex and striatum,[19] operating alongside PCP's direct D2 receptor binding[1] and DAT inhibition.[14] The three-way convergence produces dopaminergic activation exceeding what any single mechanism would predict.
Why it matters
PCP is the only drug class that reliably reproduces both positive symptoms (hallucinations, paranoia) and negative symptoms (emotional withdrawal, cognitive disruption) of schizophrenia in healthy volunteers.[4][15] This observation provided the empirical foundation for the NMDA hypofunction hypothesis — the proposal that reduced NMDA receptor function on cortical interneurons is a core mechanism in schizophrenia, with downstream consequences for glutamate release, dopamine signalling, and cortical network coherence.
Chronic PCP exposure also reveals neuroplastic adaptation: repeated administration produces compensatory upregulation of NMDA receptors alongside increased NR1 subunit expression.[7] Rather than producing simple tolerance, this upregulation drives behavioural sensitisation — an augmented response upon re-exposure.
PCP intoxication can produce psychotic states lasting days to weeks[8] — far exceeding the drug's half-life even accounting for lipophilic redistribution. Whether this reflects sustained circuit disruption, slow receptor unbinding, or active metabolite contributions is unknown.
Subjective Effects[edit]
PCP's subjective character is qualitatively distinct from other dissociatives. Where ketamine tends toward introspective, dream-like dissolution, PCP produces a more externalised dissociation — characterised by paranoid ideation, agitation, and formal thought disorder alongside anaesthetic detachment. Set and setting exert less moderating influence than with serotonergic psychedelics; the psychotomimetic and amnestic components emerge reliably across contexts. Route of administration significantly shapes the experience: smoking produces rapid onset with a sharp peak, while oral ingestion extends the come-up and produces a more sustained, less controllable intoxication.
Compared to Ketamine, PCP is substantially more potent, produces effects lasting several times longer, and carries far greater risk of prolonged psychosis.[8] Compared to dextromethorphan, PCP's profile is more dominated by psychotomimesis and motor activation than by sedation.
Effect Grid
At common doses (~5-10 mg smoked/insufflated), the full dissociative experience manifests. Frank dissociation — a profound sense of separation between mind and body — dominates. Psychotomimetic effects emerge: both positive symptoms (hallucinations, paranoid ideation, thought disorder) and negative symptoms (emotional withdrawal, reduced motivation, flattened affect). Amnesia becomes significant, often covering large portions of the experience.
Physically, muscle rigidity, pronounced nystagmus, hypertension (60% of clinical cases), and tachycardia are expected. Motor coordination is severely impaired. Analgesia is pronounced — injuries sustained during intoxication may go unnoticed.
The primary experience lasts 4-8 hours, but residual cognitive effects and mood disturbance can persist for 24-48 hours. Sleep is typically disrupted for the duration of intoxication.
Modeled from the effect's dose-dependence curve — not per-substance measurements.
Depth perception distortion · Touch suppression · Auditory distortion · Perspective distortion · Auditory misinterpretation · Visual acuity suppression · Visual haze / noise · Auditory suppression · Dreaming suppression · Peripheral misidentification · Peripheral vision distortion · Flashbacks · Tracers · Visual drifting · Visual morphing · Auditory hallucinations · External hallucinations · Visual processing suppression · Internal hallucinations · Perspective hallucinations · Persisting hallucinations
Auditory misinterpretation · Visual acuity suppression · Visual haze / noise · Auditory suppression · Dreaming suppression · Peripheral misidentification · Peripheral vision distortion · Flashbacks · Tracers · Visual drifting · Visual morphing · Auditory hallucinations · External hallucinations · Visual processing suppression · Internal hallucinations · Perspective hallucinations · Persisting hallucinations
Dizziness · Restlessness · Body high · Involuntary body movements · Sedation · Stimulation · Vasoconstriction · Excessive sweating · Heart rate perception changes · Muscle relaxation · Muscle tension · Nausea · Physical fatigue · Pupil dilation · Trembling · Wakefulness · Appetite suppression · Bodily heaviness · Bodily lightness · Breathing alteration · Dry mouth · Headache · Insomnia · Laughter fits · Salivation · Spontaneous body sensations · Vomiting · Tingling / electric sensations · Bodily dissociation · Tactile hallucination · Phantom limb sensations
Involuntary body movements · Sedation · Stimulation · Excessive sweating · Heart rate perception changes · Muscle relaxation · Muscle tension · Nausea · Physical fatigue · Pupil dilation · Trembling · Wakefulness · Appetite suppression · Bodily heaviness · Bodily lightness · Breathing alteration · Dry mouth · Headache · Insomnia · Laughter fits · Salivation · Spontaneous body sensations · Vomiting · Tingling / electric sensations · Bodily dissociation · Tactile hallucination · Phantom limb sensations
Memory fragmentation · Memory suppression · Thought disorganization · Analysis suppression · Focus suppression · Language suppression · Cognitive dysphoria · Cognitive euphoria · Cognitive fatigue · Delusions of sobriety · Pattern recognition suppression · Suggestibility enhancement · Immersion enhancement · Motivation suppression · Thought deceleration · Thought loops · Humor enhancement · Thought acceleration · Amnesia · Delirium · Delusions
Analysis suppression · Focus suppression · Language suppression · Cognitive dysphoria · Cognitive euphoria · Cognitive fatigue · Pattern recognition suppression · Suggestibility enhancement · Immersion enhancement · Motivation suppression · Thought deceleration · Thought loops · Humor enhancement · Thought acceleration · Amnesia · Delirium · Delusions
Emotional lability · Euphoria · Emotional suppression · Empathy suppression · Anhedonia · Mania · Anxiety suppression
Empathy suppression · Anhedonia · Anxiety suppression
Social disconnection · Craving · Disinhibition · Sociability suppression · Ego inflation · Sociability enhancement · Cognitive disconnection · Boundary dissolution · Ego dissolution · Identity alteration
Ego inflation · Sociability enhancement · Cognitive disconnection · Boundary dissolution · Ego dissolution · Identity alteration
Timeline
First effects 20-60 minutes after oral ingestion. Gradual emergence of numbness, mild euphoria, and faint dissociative detachment.
Effects build over 30-60 minutes toward peak. Dissociation, analgesia, and altered proprioception intensify progressively. Nystagmus and ataxia develop.
Peak plasma at approximately 90 minutes post-ingestion. Full dissociative-psychotomimetic state sustained for 1. 5-3 hours.
Extended plateau phase reflecting high oral bioavailability and long half-life. Dissociation and cognitive impairment gradually decline but remain significant.
Slow return toward baseline over 2-5 hours. Residual confusion, emotional flatness, and physical fatigue. Perceptual normalisation is gradual.
Residual cognitive dulling and mood disturbance for 12-48 hours or longer. High oral bioavailability produces sustained plasma levels; lipophilic redistribution can cause symptom recurrence.
⚠ Avoid driving or operating machinery for at least 24 hours, and longer after strong doses — the long half-life means significant drug remains in the body well past subjective resolution.
Safety[edit]
- Acute toxicity
- High
- Chronic toxicity
- High
- Withdrawal
- Mild
- Tolerance buildup
- moderate
- Tolerance reset
- —
- Physical
- Low
- Psychological
- Moderate
- Compulsive redosing
- Moderate
- Dose escalation
- Moderate
- Cross-tol.
- ketamine · dextromethorphan · MK-801
Toxicity
Acute toxicity
At 20 mg or above, seizures, coma, and death risk increase substantially.[6] No confirmed lethal dose has been established in humans. Clinical signs of acute poisoning include involuntary eye movements in 60–90% of cases,[6] muscle breakdown in about 70%,[6] elevated blood pressure in 60%, and agitation with hallucinations and violent behaviour.[6]
Muscle breakdown is the major complication: it releases proteins into the bloodstream that can block the kidneys and cause kidney failure.
Cardiovascular toxicity
High blood concentrations may disrupt heart rhythm.[17] No large clinical studies on PCP-induced heart rhythm abnormalities have been published.
Recurrent toxicity
PCP accumulates in fat tissue and can leach back into the bloodstream days to months after initial exposure.[6] Patients who appear to have recovered can re-present with renewed intoxication without taking any more drug.
PCP-alcohol interaction
Combining PCP with alcohol reduces the lethal dose of PCP by approximately 20% and produces complete loss of motor function at modest combined amounts.[18] This interaction likely explains the high rate of drowning and accidental death when PCP and alcohol are combined.
Chronic toxicity
Chronic use is associated with cognitive impairment, persistent psychotic symptoms, and personality changes. The brain compensates for repeated glutamate blockade by upregulating glutamate receptors,[16] making future responses stronger rather than weaker.
Psychological risks
PCP induces both the positive symptoms of schizophrenia (paranoia, hallucinations, thought disorder) and the negative symptoms (emotional withdrawal, thought deceleration).[15] This dual profile distinguishes it from stimulant psychosis, which produces only the positive symptoms.
Beyond the acute experience, a single high-dose exposure can trigger psychosis lasting days to weeks.[7] PCP also specifically worsens symptoms in people with existing psychotic illness.[19] Profound amnesia covering the entire intoxication period is common, and agitation with violent behaviour is well-documented in acute poisoning.[6]
Tolerance and dependence
PCP shows reinforcing properties in animal models and produces tolerance with repeated use.[5][7] Rather than simply losing effect, the brain upregulates glutamate receptors and generates heightened responses on re-exposure.[16] Cross-tolerance exists with other glutamate blockers including ketamine and dextromethorphan.
In humans, physical dependence is reported anecdotally among chronic heavy users. Withdrawal features include craving, anxiety, low mood, tremors, and diarrhea. No controlled withdrawal study has been published.[7]
Drug Interactions
NMDA antagonist stacking: Combining PCP with other glutamate blockers such as Dextromethorphan amplifies dissociation, respiratory depression, and cardiovascular toxicity. Both drugs occupy the same site in the same channel.
Alcohol: Alcohol reduces the lethal dose of PCP by about 20% and causes complete motor incapacitation at modest combined amounts.[18] Drowning and aspiration are the primary causes of accidental death.
CNS depressants: Opioids and GHB/GBL add to breathing suppression through overlapping pathways.
Serotonergic drugs: Certain tryptamines (including 5-MeO-DMT and related compounds) and tramadol pose a risk of serotonin overload.safety citation needed Tramadol also adds breathing suppression risk.
Stimulants: Amphetamines, cocaine, and MDMA compound cardiovascular stress. PCP and cocaine both compete at the DAT, creating unpredictable dopaminergic amplification.
Contraindications
7 knownPCP carries specific risks for people with:
- Psychotic disorders or schizophrenia: PCP specifically worsens characteristic psychotic symptoms.[19] Any personal or family history of psychosis substantially increases risk of prolonged psychotic reactions.
- Seizure disorders: PCP directly provokes seizures at doses above approximately 20 mg.[6]
- Heart or blood vessel disease: Elevated blood pressure occurs in 60% of intoxication cases. Dangerously high blood pressure and brain bleeding are documented complications.
- Liver impairment: Impaired clearance increases accumulation and prolongs intoxication.
- Kidney impairment: Muscle breakdown occurs in 70% of clinical cases.[6] Pre-existing kidney problems dramatically increase the risk of kidney failure.
- Pregnancy: PCP crosses the placenta. Neonatal effects and developmental toxicity are reported.safety citation needed
Relative contraindications include bipolar disorder, pre-existing anxiety disorders, and concurrent use of medications processed by liver enzymes CYP3A4, CYP2D6, or CYP2C19.[20]
Harm Reduction[edit]
Forms & Identification
The predominant street form is liquid PCP applied to plant material — cigarettes, joints, or parsley. Dosing from this form is essentially impossible: concentration varies between batches, absorption by plant material is uneven, and two dips from the same jar can deliver very different doses.
Crystalline powder and tablet forms allow marginally better control through weighing, but street purity varies and substitution with other dissociatives is documented. Any PCP obtained outside a controlled setting should be treated as having unknown concentration until tested.
Guidelines
- Test the substance. Use reagent testing to confirm identity. PCP is sold as or substituted with other dissociatives.
- Start extremely low. The margin between a recreational and dangerous dose is narrow. If using liquid-dipped material, take a single small inhalation and wait at least 30 minutes before considering more.
- Do not use alone. A sober sitter is not optional with PCP. The drug's amnestic, analgesic, and psychotomimetic properties can produce dangerous behaviour the user will not remember.
- Stay hydrated but stationary. PCP raises body temperature and can cause muscle breakdown. Drink water, avoid physical exertion, and stay in a safe space.
- Clear the schedule. Effects can last 4–8 hours, with residual effects persisting much longer. Do not plan to drive, work, or care for dependents.
- Remove access to danger. Lock away keys, close windows, and keep the environment free of hazards before dosing.
Set & Setting
PCP is less responsive to set and setting than serotonergic psychedelics. Its psychotomimetic effects emerge pharmacologically regardless of environment.
Hostile or chaotic surroundings reliably worsen agitation, paranoia, and violence risk. A calm, low-stimulation environment with a sober sitter is essential. The sitter should understand that the person may become unresponsive, agitated, or combative without warning.
PCP impairs judgment, causes amnesia, and can provoke aggressive behaviour. Access to vehicles, heights, bodies of water, and weapons should be removed before dosing.
Aftercare & integration. PCP's long duration and amnesia make the post-experience period disorienting. The person may have little or no memory of what occurred, and reorientation can take hours to days.
Physical recovery should prioritise hydration and rest. Muscle soreness may indicate muscle breakdown. Dark or brown urine is a medical emergency requiring immediate hospital attention. Avoid physical exertion for at least 48 hours.
Persistent paranoia, confusion, or psychotic symptoms beyond 48 hours warrant professional evaluation. PCP can trigger lasting psychological disturbance in predisposed individuals. Familiar environments and trusted company support grounding.
Recovery & Support
PCP dependence is real but poorly characterised. Craving, anxiety, and low mood are commonly reported on stopping. The absence of a defined physical withdrawal does not mean stopping is easy.
Professional support is recommended for anyone struggling to reduce or stop PCP use. SAMHSA's National Helpline (1-800-662-4357) provides free referrals in the United States. Narcotics Anonymous offers peer support. Cognitive behavioural therapy has the strongest evidence base for dissociative use disorders.
Recovery resources, crisis lines, and support pathways → View all
Emergency Response
Recognising an emergency:
- Seizures or uncontrollable muscle rigidity
- Body feels extremely hot to the touch (dangerous overheating)
- Complete unresponsiveness — not reacting to voice or touch
- Dark or absent urine (sign of kidney failure from muscle breakdown)
- Violent or self-harming behaviour that cannot be safely managed
- Psychosis lasting more than 24 hours
Immediate steps:
- 1. Call emergency services immediately if any of the above are present.
- 2. Do not attempt to physically restrain the person unless they pose immediate danger to themselves or others. Restraint can worsen muscle breakdown.
- 3. Keep the person in a quiet, dimly lit space. Reduce all stimulation.
- 4. If the person is unconscious and breathing, place them in the recovery position.
- 5. Do not induce vomiting.
- 6. Monitor breathing continuously.
What to tell the dispatcher: State that the person has taken PCP (or a dissociative), the approximate amount and time if known, and describe current symptoms. Good Samaritan laws in many jurisdictions protect people who call for help during a drug emergency.
Legal Status[edit]
Phencyclidine is among the most restrictively scheduled dissociatives worldwide, with no approved medical use in any jurisdiction despite its US Schedule II classification.
| Jurisdiction | Classification | Key provisions |
|---|---|---|
| United States | Schedule II (Controlled Substances Act) | Initially Schedule III (1970); upgraded to Schedule II in mid-1970s during the street drug epidemic. No current approved medical use despite Schedule II status[21][4] |
| United Kingdom | Class A (Misuse of Drugs Act 1971) | Maximum penalties for possession and supply; most restrictive UK classification |
| Canada | Schedule I (Controlled Drugs and Substances Act) | Most restrictive Canadian schedule |
| International | Schedule I (1971 UN Convention on Psychotropic Substances) | Convention also controls PCP analogues: eticyclidine (PCE), rolicyclidine (PHP), tenocyclidine (TCP) |
| Australia | Schedule 9 (Prohibited Substance) | No permitted use outside approved researchcitation needed |
Legal status changes frequently and varies by jurisdiction. This information is not legal advice.
Safety[edit]
- Acute toxicity
- High
- Chronic toxicity
- High
- Withdrawal
- Mild
- Tolerance buildup
- moderate
- Tolerance reset
- —
- Physical
- Low
- Psychological
- Moderate
- Compulsive redosing
- Moderate
- Dose escalation
- Moderate
- Cross-tol.
- ketamine · dextromethorphan · MK-801
Toxicity
Acute toxicity
PCP has a narrow margin between recreational doses and doses producing severe toxicity. At 20 mg or above, seizures, coma, and death risk increase substantially.[6] No confirmed lethal dose has been established in humans; fatal overdoses are documented clinically but no systematic dose-mortality relationship exists.
Clinical findings in acute poisoning include involuntary eye movements (horizontal, vertical, or rotary) in 60–90% of cases,[6] muscle breakdown in approximately 70% of cases,[6] elevated blood pressure in 60%, rapid heart rate in 30%, low blood sugar in 22%, and agitation with confusion, hallucinations, and violent behaviour.[6]
Major complications include muscle breakdown with secondary kidney failure, dangerously elevated blood pressure, brain bleeding, aspiration into the lungs, and seizures.
Cardiovascular toxicity
Computer modelling predicts potential heart rhythm disruption at high blood concentrations.[20] No large clinical series on PCP-induced heart rhythm abnormalities have been published.
Recurrent toxicity
Due to accumulation in fatty tissues, PCP can redistribute and cause recurrent symptoms days to months after initial exposure.[6] Patients discharged after apparent resolution can re-present with renewed intoxication without further drug use.
PCP-alcohol interaction
Animal studies demonstrate synergistic toxicity: low doses of alcohol reduced the lethal dose of PCP by approximately 20% in mice. More significant was marked synergism for motor impairment — co-ingestion of moderate doses produced total loss of motor ability.[21] This interaction likely explains the high rate of drowning and accidental death when PCP and alcohol are combined.
Chronic toxicity
Chronic PCP use is associated with cognitive impairment, persistent psychotic symptoms, and personality changes. Animal data show compensatory upregulation of NMDA receptors after chronic exposure,[7] a change that may underlie sensitisation and vulnerability to psychotic relapse.
Psychological risks
PCP produces the most complete pharmacological model of schizophrenia available. In healthy individuals, it induces both positive symptoms (hallucinations, paranoia, thought disorder) and negative symptoms (emotional withdrawal, anhedonia, motor slowing) — a dual profile that distinguishes it from stimulant-induced psychosis, which generates only positive symptoms.[4]
Acute psychological risks include paranoid ideation with auditory and visual hallucinations, violence and agitation,[6] prolonged psychosis lasting days to weeks after a single high-dose exposure,[8] worsening of existing psychotic symptoms in people with schizophrenia,[22] and profound amnesia — often complete for the intoxication period.
Tolerance and dependence
Tolerance develops with repeated use, though the precise time-course in humans is poorly characterised.[8] In animal models, chronic PCP produces behavioural sensitisation — an augmented response on re-exposure — rather than simple tolerance, accompanied by NMDA receptor upregulation.[7] Cross-tolerance exists with other NMDA antagonists including ketamine, dextromethorphan, and MK-801.
PCP shows reinforcing properties in animal self-administration models.[5] Withdrawal from continuous PCP infusion in rats disrupted normal behaviour, and methoxetamine reversed these effects in a dose-dependent manner.[23]
In humans, physical dependence is reported anecdotally in chronic heavy users, with described withdrawal features including craving, anxiety, low mood, tremors, facial twitching, and diarrhea. No formal controlled withdrawal study has been published. Murray notes that "answers to questions about its addictive potential or development of tolerance are not clear".[8]
Drug Interactions
PCP's interaction risk stems from three mechanisms: NMDA receptor blockade, dopamine amplification, and cardiovascular stimulation.
NMDA antagonist stacking: Combination with other NMDA antagonists — particularly Dextromethorphan — produces unpredictable intensification of dissociation, respiratory depression, and cardiovascular toxicity. Both compounds block the same receptor channel site.
Serotonergic combinations: 5-MeO-substituted tryptamines (5-MeO-DMT, 5-MeO-DiPT, 5-MeO-DALT, 5-MeO-MiPT) and α-methyltryptamine (AMT) pose serotonin syndrome risk when combined with PCP.safety citation needed Tramadol creates dual risk of serotonin syndrome and breathing suppression.
Central nervous system depressants: GHB/GBL and opioids produce additive breathing suppression. The PCP-alcohol interaction is well-characterised: synergistic motor impairment at modest doses, with approximately 20% reduction in lethal dose in mice.[21] Drowning and aspiration are the primary mechanisms of accidental death.
Cardiovascular stacking: Stimulants (amphetamines, cocaine, MDMA, PMA, fluoroamphetamines, fenethylline) worsen PCP's baseline cardiovascular stress. PCP and cocaine both compete at the DAT, creating unpredictable dopaminergic effects alongside additive cardiovascular strain.
Contraindications
7 known- Psychotic disorders and schizophrenia: PCP specifically worsens characteristic psychotic symptoms in people with established psychotic illness.[22] Any personal or family history of psychosis substantially increases risk of prolonged psychotic reactions.
- Seizure disorders: PCP is directly seizure-provoking at doses above approximately 20 mg.[6]
- Heart or blood vessel disease: Elevated blood pressure occurs in 60% of intoxication cases; dangerously high blood pressure and brain bleeding are documented complications.
- Liver impairment: PCP is broken down by the liver; impaired clearance increases risk of accumulation and prolonged intoxication.
- Kidney impairment: Muscle breakdown occurs in 70% of clinical intoxication cases.[6] Pre-existing kidney problems dramatically increase the risk of kidney failure.
- Pregnancy: PCP crosses the placenta. Neonatal effects and developmental toxicity are reported.safety citation needed
Relative contraindications include bipolar disorder (risk of manic episodes), pre-existing anxiety disorders (agitation and panic are common), and concurrent use of medications metabolised by CYP3A4, CYP2D6, or CYP2C19.[24]
Harm Reduction[edit]
Forms & Identification
PCP's predominant street form — liquid applied to plant material (cigarettes, joints, parsley) — makes accurate dosing essentially impossible. The concentration of liquid PCP varies dramatically between batches, and the amount absorbed by plant material is uneven. Two dips from the same jar can deliver wildly different doses.
Crystalline powder and tablet forms allow marginally better dose control through weighing, but street purity varies and substitution with other dissociatives or adulterants is documented. Any PCP obtained outside a controlled setting should be assumed to have unknown concentration until tested.
Guidelines
- Test the substance. Use reagent testing to confirm identity. PCP is sold as or substituted with other dissociatives.
- Start extremely low. The margin between a recreational and dangerous dose is narrow. If using liquid-dipped material, take a single small inhalation and wait at least 30 minutes before considering more.
- Do not use alone. A sober sitter is not optional with PCP. The drug's amnestic, analgesic, and psychotomimetic properties can produce dangerous behaviour the user will not remember.
- Stay hydrated but stationary. PCP raises body temperature and can cause muscle breakdown. Drink water, avoid physical exertion, and stay in a safe space.
- Clear your schedule. Effects can last 4–8 hours, with residual effects persisting much longer. Do not plan to drive, work, or care for dependents.
- Remove access to danger. Lock away keys, close windows, and keep the environment free of hazards before dosing.
Set & Setting
PCP is less responsive to set and setting than serotonergic psychedelics — its psychotomimetic effects emerge pharmacologically regardless of environment. However, hostile or chaotic surroundings reliably worsen agitation, paranoia, and risk of violence.
A calm, controlled, low-stimulation environment with a sober sitter is essential. PCP impairs judgment, produces amnesia, and can provoke aggressive behaviour; the user should not have access to vehicles, heights, bodies of water, or weapons. The sitter should understand that the person may become unresponsive, agitated, or combative without warning.
Aftercare & integration. PCP's long duration and amnestic properties make the post-experience period particularly disorienting. The user may have little or no memory of what occurred, and reorientation to normal reality can take hours to days.
Physical recovery should prioritise hydration and rest. Muscle soreness may indicate muscle breakdown — dark or brown urine is a medical emergency requiring immediate hospital attention. Avoid physical exertion for at least 48 hours after use.
Persistent paranoia, confusion, or psychotic symptoms beyond 48 hours warrant professional evaluation. PCP can trigger lasting psychological disturbance in predisposed individuals. Familiar environments, trusted company, and gentle re-engagement with routine support grounding.
Recovery & Support
PCP dependence is real but poorly characterised. Craving, anxiety, and low mood are commonly reported on cessation. The absence of a well-defined physical withdrawal does not mean stopping is easy — psychological compulsion and environmental triggers can be powerful.
Professional support is recommended for anyone struggling to reduce or stop PCP use. SAMHSA's National Helpline (1-800-662-4357) provides free referrals in the United States. Mutual aid groups such as Narcotics Anonymous offer peer support. Cognitive behavioural therapy has the strongest evidence base for dissociative and stimulant use disorders.
Recovery resources, crisis lines, and support pathways → View all
Emergency Response
Recognising an emergency:
- Seizures or uncontrollable muscle rigidity
- Body feels extremely hot to the touch (dangerous overheating)
- Complete unresponsiveness — not reacting to voice or touch
- Dark or absent urine (sign of kidney failure from muscle breakdown)
- Violent or self-harming behaviour that cannot be safely managed
- Psychosis lasting more than 24 hours
Immediate steps:
- 1. Call emergency services immediately if any of the above are present.
- 2. Do not attempt to physically restrain the person unless they pose immediate danger to themselves or others — restraint can worsen muscle breakdown.
- 3. Keep the person in a quiet, dimly lit space. Reduce all stimulation.
- 4. If the person is unconscious and breathing, place them in the recovery position.
- 5. Do not induce vomiting.
- 6. Monitor breathing continuously.
What to tell the dispatcher: State that the person has taken PCP (or a dissociative), the approximate amount and time if known, and describe current symptoms. Good Samaritan laws in many jurisdictions protect people who call for help during a drug emergency.
Legal Status[edit]
Phencyclidine is among the most restrictively scheduled dissociatives worldwide. Despite its US Schedule II classification — which nominally implies some accepted medical use — PCP has no approved therapeutic application in any jurisdiction. The scheduling reflects historical clinical use (Sernyl, 1963–1965) rather than any current medical indication.
| Jurisdiction | Classification | Key provisions |
|---|---|---|
| United States | Schedule II (Controlled Substances Act) | Initially Schedule III (1970); upgraded to Schedule II in mid-1970s during the street drug epidemic. No current approved medical use despite Schedule II status[25][3] |
| United Kingdom | Class A (Misuse of Drugs Act 1971) | Maximum penalties for possession and supply; most restrictive UK classification |
| Canada | Schedule I (Controlled Drugs and Substances Act) | Most restrictive Canadian schedule |
| International | Schedule I (1971 UN Convention on Psychotropic Substances) | Convention also controls PCP analogues: eticyclidine (PCE), rolicyclidine (PHP), tenocyclidine (TCP) |
| Australia | Schedule 9 (Prohibited Substance) | No permitted use outside approved researchcitation needed |
Frequently asked questions
What is PCP?
PCP is a synthetic dissociative of the arylcyclohexylamine class, first synthesized in 1956 and briefly marketed as the surgical anesthetic Sernyl. It acts as a noncompetitive NMDA receptor antagonist with secondary D2 dopamine receptor affinity.
How long does PCP last?
Total duration by route of administration — Smoked: 4 – 8 hours; Insufflated: 4 – 8 hours; Oral: 4 – 8 hours. Ranges vary with dose and individual factors; see the duration table for onset, peak, and after-effect phases.
Where can I find dosage information for PCP?
Psychedex publishes a dosage table for PCP on this page covering these routes of administration: smoked, insufflated, oral. Dose values are presented only in that table, always alongside their route of administration.
What are dangerous combinations with PCP?
The highest-severity documented interactions for PCP: GHB, GBL (Lethal), Ibogaine (Lethal), 5-HTP, Tryptophan (Dangerous), Alpha-2 adrenergic receptor antagonist (Dangerous), Amphetamines (Dangerous). See the interactions section for the full list with mechanisms and severity levels.
Is PCP addictive?
Psychedex records tolerance and dependence data rather than a yes/no rating. Recorded tolerance indicators for PCP: tolerance builds moderate; cross-tolerance develops with ketamine, dextromethorphan, MK-801, methoxetamine. See the article's dependence and safety sections for recorded dependence data.
experience reports
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First-person accounts of subjective effects, timing, and outcomes — submitted for harm reduction.
references
- [1] ^abcdSeeman P, Ko F, Tallerico T (2005) Dopamine receptor contribution to the action of PCP, LSD and ketamine psychotomimetics — Molecular Psychiatry PMID:15852061
- [2]
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- [4]
- [5] ^abNicholson KL, Mansbach RS, Menniti FS, Balster RL (2007) The phencyclidine-like discriminative stimulus effects and reinforcing properties of the NR2B-selective NMDA antagonist CP-101 606 in rats and rhesus monkeys. — Behavioural Pharmacology PMID:17989511
- [6]
references
- [1] ^abcdSeeman P, Ko F, Tallerico T (2005) Dopamine receptor contribution to the action of PCP, LSD and ketamine psychotomimetics — Molecular Psychiatry PMID:15852061
- [2]
- [3]
- [4] ^abcJavitt DC, Zukin SR (1991) Recent advances in the phencyclidine model of schizophrenia — American Journal of Psychiatry PMID:1654746
- [5] ^abNicholson KL, Mansbach RS, Menniti FS, Balster RL (2007) The phencyclidine-like discriminative stimulus effects and reinforcing properties of the NR2B-selective NMDA antagonist CP-101 606 in rats and rhesus monkeys. — Behavioural Pharmacology PMID:17989511
- [6]