Disorders Due to Use of Dissociative Drugs, Including Ketamine and Phencyclidine [PCP] - ICD-11 Code: 6C4D

1. Introduction

Disorders due to the use of dissociative drugs represent a growing challenge for mental health professionals worldwide. These substances, which include mainly ketamine and phencyclidine (PCP), produce unique psychoactive effects characterized by sensations of disconnection from reality, from one's own body, and from the surrounding environment.

Ketamine, originally developed as a medical anesthetic, continues to be widely used in legitimate clinical contexts, especially in low- and middle-income countries and in emergency situations. Paradoxically, this same substance has become a popular recreational drug in various countries, being consumed in recreational settings such as parties and nightclubs. Recently, it has been investigated as an innovative treatment for treatment-resistant depressive disorders, adding complexity to its clinical profile.

The clinical importance of these disorders lies not only in the growing prevalence of recreational use, but also in the significant consequences for the physical and mental health of users. Chronic use can result in severe bladder damage, cognitive impairment, and development of dependence. Phencyclidine, although less prevalent globally, presents particular risks due to the potential to induce violent and self-injurious behaviors.

The correct coding of these disorders in ICD-11 is critical to ensure accurate epidemiological records, facilitate research on effective treatments, allow adequate planning of mental health services, and ensure appropriate reimbursement for services provided. The clear distinction between recreational use, appropriate medical use, and use-related disorders is fundamental to contemporary clinical practice.

2. Correct ICD-11 Code

Code: 6C4D

Description: Disorders due to use of dissociative drugs, including ketamine and phencyclidine [PCP]

Parent category: Disorders due to substance use

Official definition: Disorders due to use of dissociative drugs are characterized by the pattern and consequences of use of these substances. Dissociative drugs include ketamine, phencyclidine (PCP), and their relatively rare chemical analogues.

Ketamine is an intravenous anesthetic with legitimate medical use widely distributed, particularly in low- and middle-income countries, especially in Africa, and in emergency situations. It is currently being evaluated for the treatment of mental disorders, including treatment-resistant depressive disorders. As a drug for non-medical use, it may be administered orally, nasally, or injected, producing a sensation of euphoria, but also emerging hallucinations and dissociation that are recognized as unpleasant side effects depending on the dose.

Phencyclidine has more restricted global distribution and has similar euphoric and dissociative effects. Its use may result in bizarre behavior, uncharacteristic of the individual, including self-injury. Dependence on dissociative drugs is described in the scientific literature; however, a withdrawal syndrome is not recognized by most authorities. Various mental disorders induced by dissociative drugs are recognized within this classification.

3. When to Use This Code

The code 6C4D should be used in specific clinical scenarios where there is clear evidence of a disorder related to the use of dissociative drugs:

Scenario 1: Compulsive use with functional impairment A 28-year-old patient presents with a pattern of regular ketamine use over the past 18 months, initially on weekends, but progressively increasing to almost daily use. Reports difficulty controlling consumption, failed attempts at reduction, and significant impairment at work, with multiple absences and decreased performance. Also presents with social isolation and abandonment of previously pleasurable activities.

Scenario 2: Dependence with physical symptoms An individual with a history of chronic ketamine use for three years, consuming increasing doses to obtain the same effects (tolerance). Presents with severe urinary symptoms, including pain on urination, urinary urgency, and hematuria, diagnosed as ketamine-induced cystitis. Continues use despite knowledge of these physical harms.

Scenario 3: PCP use with risk-taking behavior A patient with a recurrent pattern of phencyclidine use presenting with repeated episodes of aggressive and disorganized behavior during intoxication. History of self-inflicted injuries during dissociative states, involvement in risky situations, and inability to cease use despite recurrent negative consequences.

Scenario 4: Substance-induced mental disorder A regular ketamine user develops persistent psychotic symptoms, including paranoid delusions and visual hallucinations that persist beyond the period of acute intoxication. The symptoms are clearly temporally related to substance use and are not better explained by another primary mental disorder.

Scenario 5: Cognitive impairment related to use A patient with a history of intense use of dissociative drugs over a prolonged period presents with significant cognitive deficits, including memory problems, concentration difficulties, and slowing of mental processing that interfere with daily and occupational activities.

Essential criteria that must be present:

Pattern of use that causes clinically significant impairment or distress
Loss of control over use
Prioritization of substance use over other activities
Continuation of use despite harmful consequences
Evidence of tolerance or characteristics of dependence

4. When NOT to Use This Code

It is essential to distinguish situations where code 6C4D is not appropriate:

Appropriate medical use of ketamine: When ketamine is administered in a controlled medical context for anesthesia, sedation, or treatment of treatment-resistant depression, under adequate professional supervision, without development of a problematic pattern of use, it is not coded as a disorder.

Occasional recreational use without consequences: If there is hazardous use of dissociative drugs, including ketamine and phencyclidine (PCP), but without development of a pattern of dependence or drug-induced mental disorder, code QE11 (Hazardous use of dissociative drugs, including ketamine and phencyclidine) should be used.

Isolated acute intoxication: A single episode of intoxication from dissociative drugs without an established pattern of problematic use should be coded as acute intoxication, not as a disorder due to use.

Primary mental disorders: When psychotic, depressive, or anxiety symptoms precede the use of dissociative drugs or persist during prolonged periods of abstinence, they likely represent primary mental disorders that should be coded separately.

Use of other substances: Disorders related to the use of other classes of substances (alcohol, cannabis, opioids, stimulants) should be coded with their respective specific codes, even if there is concomitant use of dissociatives.

Unintentional exposure: Accidental exposure or non-consensual administration of dissociative drugs does not constitute a disorder due to use.

5. Step-by-Step Coding Process

Step 1: Assess Diagnostic Criteria

Confirmation of diagnosis requires systematic evaluation through structured clinical interview. The professional should investigate:

Detailed history of use: Age of onset, current frequency, quantities consumed, routes of administration, pattern of use over time, attempts at cessation or reduction.

Evidence of loss of control: Use in larger quantities or for longer periods than intended, persistent desire or unsuccessful efforts to control use.

Functional impairments: Impact on work, studies, family relationships, social functioning, recreational activities, daily responsibilities.

Physical and mental consequences: Urinary, cognitive, psychological, neurological problems related to use.

Useful instruments include validated questionnaires for substance use assessment, dependency severity scales, and neuropsychological evaluations when indicated.

Step 2: Verify Specifiers

After confirming the primary diagnosis, determine:

Temporal pattern: Current use (active), in early remission (1-12 months), in sustained remission (more than 12 months).

Severity: Mild, moderate, or severe, based on the number of criteria met and the degree of functional impairment.

Presence of induced disorders: Identify whether there are mental disorders induced by dissociative drugs (psychotic, mood, anxiety, cognitive) that require additional coding.

Physiological characteristics: Presence of significant tolerance or characteristics of dependence.

Step 3: Differentiate from Other Codes

6C40 - Disorders due to use of alcohol: Differentiated by the specific substance involved. Alcohol produces intoxication with disinhibition, motor incoordination, and characteristic withdrawal syndrome with tremors and seizure risk, while dissociatives cause perceptual disconnection and dissociation without recognized withdrawal syndrome.

6C41 - Disorders due to use of cannabis: Cannabis produces effects predominantly related to relaxation, mild perceptual alterations, and increased appetite, without the profound dissociative effects characteristic of ketamine and PCP. Cannabis is not associated with bladder damage.

6C42 - Disorders due to use of synthetic cannabinoids: Although they may produce psychotic effects, synthetic cannabinoids act on cannabinoid receptors, not on NMDA receptors like dissociative drugs, and present a distinct profile of effects and risks.

Step 4: Required Documentation

Checklist of mandatory information:

Specific substance used (ketamine, PCP, analog)
Routes of administration
Frequency and quantity of use
Duration of problematic pattern
Specific diagnostic criteria met
Documented functional impairments
Physical and mental complications
Previous treatment attempts
Concomitant use of other substances
Social and environmental context of use

Adequate record: Clearly document the temporal relationship between substance use and symptoms presented, including periods of abstinence if applicable, to differentiate from primary mental disorders.

6. Complete Practical Example

Clinical Case

Marina, 32 years old, creative professional, presents to the mental health service referred by her family physician due to persistent urinary symptoms and concerns about her substance use.

Initial presentation: Patient reports recreational ketamine use initiated four years ago in a social context. Initially, she used monthly at parties, but over the last 18 months the pattern has intensified progressively. Currently uses ketamine 4-5 times per week, frequently alone at home. She describes a feeling of need to use to "disconnect" from stress and reports multiple failed attempts to reduce consumption.

Symptoms and consequences: She developed severe urinary symptoms six months ago, including intense pain upon urination, need to urinate every 30 minutes, and episodes of blood in urine. Urological evaluation confirmed ketamine-induced cystitis with significant bladder changes. Despite the diagnosis and medical guidance, she continued using.

At work, she presented significant decline in productivity, with difficulty concentrating and frequent absences. Social relationships deteriorated, with progressive isolation. Family expresses growing concern. She also reports episodes of "brain fog" and memory difficulties that persist even when not under the effect of the drug.

Assessment performed: Structured clinical interview revealed a pattern of compulsive use with loss of control, use in increasing amounts (tolerance), prioritization of use over other activities, and continuation despite serious physical consequences. She does not present psychotic symptoms, but demonstrates mild cognitive impairment on informal neuropsychological evaluation. She denies problematic use of other substances, although she reports occasional social alcohol consumption.

Diagnostic reasoning: The case presents multiple criteria for disorder due to dissociative drug use: loss of control over use, compulsive pattern, tolerance, significant functional impairment in multiple areas, serious physical consequences (cystitis), and continuation of use despite knowledge of harm. Cognitive impairment may represent an effect of chronic use.

Step-by-Step Coding

Criteria analysis:

✓ Pattern of use causing clinically significant impairment
✓ Loss of control (failed reduction attempts)
✓ Prioritization of use (social isolation, occupational impairment)
✓ Continuation despite harmful consequences (severe cystitis)
✓ Tolerance (need for increasing doses)
✓ Use of specific substance: ketamine (dissociative drug)

Primary code chosen: 6C4D - Disorders due to use of dissociative drugs, including ketamine and phencyclidine [PCP]

Complete justification: Code 6C4D is appropriate because the patient presents an established pattern of problematic ketamine use (dissociative drug) with multiple dependence criteria, significant functional impairment, and serious physical consequences. The pattern does not fit isolated hazardous use, but rather an established disorder with dependence characteristics.

Specifiers:

Severity: Moderate to severe (multiple criteria, significant consequences)
Temporal pattern: Current (active use)
With physical complications (ketamine-induced cystitis)
Possible cognitive impairment related

Applicable complementary codes:

Code for ketamine-induced cystitis (genitourinary system)
Possible additional code for cognitive impairment if confirmed on formal evaluation

7. Related Codes and Differentiation

Within the Same Category

6C40: Disorders due to use of alcohol

When to use: When the disorder is specifically related to alcohol use, with a pattern of problematic consumption of alcoholic beverages.
Main difference: Alcohol is a central nervous system depressant with potentially severe withdrawal syndrome (tremors, seizures, delirium), whereas dissociative drugs do not present recognized withdrawal syndrome and produce characteristic dissociation.

6C41: Disorders due to use of cannabis

When to use: When there is a problematic pattern of use of marijuana or products derived from the Cannabis sativa plant.
Main difference: Cannabis acts on cannabinoid receptors producing relaxation and mild perceptual alterations, without the profound dissociative effects and without association with characteristic bladder damage of ketamine.

6C42: Disorders due to use of synthetic cannabinoids

When to use: When the disorder involves use of synthetic substances that mimic cannabis effects (such as "spice" or "K2").
Main difference: Synthetic cannabinoids act on cannabinoid receptors with greater potency than natural cannabis, but do not produce characteristic dissociation nor act on NMDA receptors like dissociatives.

Differential Diagnoses

Primary psychotic disorders: Schizophrenia or other psychotic disorders may present dissociative symptoms, but have onset independent of substance use and persist during prolonged abstinence.

Primary dissociative disorder: Dissociative disorders unrelated to substances present disconnection from reality without temporal relationship to drug use.

Isolated acute intoxication: Single episode without established pattern of problematic use requires different code.

Hazardous use (QE11): When there is a pattern of use that poses risk, but without complete criteria for established disorder.

8. Differences with ICD-10

In ICD-10, disorders related to the use of dissociative drugs were generally classified under F19 - Mental and behavioral disorders due to use of multiple drugs and use of other psychoactive substances, a broad and nonspecific category.

Main changes in ICD-11:

ICD-11 introduces the specific code 6C4D exclusively for dissociative drugs, recognizing their unique pharmacological characteristics and distinctive pattern of clinical consequences. This specificity represents a significant advance, as ketamine and PCP have a mechanism of action (NMDA receptor antagonism) completely different from other psychoactive substances.

The new classification also better reflects contemporary knowledge about these substances, including the emerging medical use of ketamine in psychiatry and the specific urological complications of chronic use, which were not adequately captured in ICD-10.

Additionally, ICD-11 eliminates the distinction between "dependence" and "abuse" present in ICD-10, adopting a dimensional approach that recognizes a spectrum of severity in disorders due to substance use.

Practical impact: More specific coding allows better epidemiological tracking of dissociative use, facilitates targeted research on effective treatments for this specific population, and enables more adequate planning of specialized services. Professionals should familiarize themselves with the new code to ensure accurate documentation.

9. Frequently Asked Questions

How is the diagnosis of disorder due to use of dissociative drugs made?

The diagnosis is primarily clinical, based on detailed interview that assesses the pattern of use, physical and psychological consequences, and degree of functional impairment. The professional should investigate history of use (onset, frequency, quantities, routes of administration), evidence of loss of control, cessation attempts, impairments in different areas of life, and medical consequences. Complementary examinations may include urological evaluation (bladder ultrasonography, cystoscopy) when there are urinary symptoms, neuropsychological testing to assess cognitive impairment, and toxicological tests to confirm recent use, although the latter have limited detection windows.

Is treatment available in public health systems?

The availability of treatment varies significantly among different regions and health systems. Many mental health services and substance dependence treatment programs offer care for disorders related to substance use, including dissociative drugs. Treatment generally involves a multidisciplinary approach with psychotherapy (especially cognitive-behavioral therapy and motivational interviewing), management of medical complications, psychosocial support, and when necessary, treatment of comorbid mental disorders. Some systems offer outpatient programs, while severe cases may require hospitalization. It is recommended to consult local mental health or substance dependence services for specific information about availability.

How long does treatment last?

The duration of treatment is highly individualized and depends on the severity of the disorder, presence of complications, comorbidities, and individual response. Typical outpatient treatments may extend for several months to years, with more intensive initial phases (weekly sessions) gradually reducing frequency as progress is made. Initial stabilization phase may last weeks to months, followed by a more prolonged maintenance phase. Complications such as severe cystitis may require prolonged urological follow-up. Cognitive recovery may be gradual, occurring over months after cessation of use. Long-term follow-up is frequently recommended to prevent relapse, with some individuals benefiting from continuous support.

Can this code be used in medical certificates?

Yes, code 6C4D can be used in official medical documentation, including certificates, when clinically appropriate and necessary. However, professionals should consider issues of confidentiality and stigma. In many situations, it may be preferable to use more general terminology such as "mental health disorder" or "medical condition" in certificates intended for employers or other parties, reserving specific coding for internal clinical documentation and communication between health professionals. The decision should balance the need for accurate documentation with protection of patient privacy and potential consequences of disclosure of substance-related diagnosis.

Is there a difference between medical use of ketamine and recreational use in coding?

Yes, there is a fundamental difference. Appropriate medical use of ketamine (anesthesia, treatment of treatment-resistant depression under supervision) is not coded as a disorder, even if there is regular administration of the substance. Code 6C4D applies only when there is a problematic pattern of use characterized by loss of control, functional impairment, and negative consequences. Patients in medical treatment with ketamine who develop additional non-prescribed use or compulsive pattern may develop a disorder that justifies coding. The distinction requires careful assessment of the context and pattern of use.

Do dissociative drugs cause withdrawal syndrome?

Unlike alcohol, benzodiazepines, or opioids, dissociative drugs are not recognized by most authorities as causing significant physical withdrawal syndrome. Chronic users may report psychological symptoms upon cessation of use (anxiety, irritability, intense craving for the drug), but do not present dangerous physiological withdrawal syndrome that requires specific medical management. This characteristic distinguishes dissociatives from other substance classes and influences treatment approaches, which may focus more on psychological and behavioral aspects than on management of physical withdrawal.

What are the most common medical complications of chronic ketamine use?

The most characteristic medical complication of chronic ketamine use is cystitis (bladder inflammation), which can progress to severe bladder damage with significant reduction in capacity, chronic pain, extreme urinary urgency, and hematuria. This condition may be irreversible in advanced cases and occasionally requires surgical intervention. Other complications include cognitive impairment (problems with memory, attention, and executive function), abdominal pain, liver problems, and rarely, hydronephrosis. PCP users may present with violent behavior during intoxication with risk of traumatic injuries. Early recognition and cessation of use are fundamental to prevent irreversible damage.

How to differentiate acute effects of ketamine from primary psychotic disorder?

The differentiation is based primarily on the temporal relationship between substance use and symptoms, and on the evolution during abstinence. Acute effects of ketamine (dissociation, perceptual alterations, disorganized thinking) occur during or immediately after use and resolve within hours to days. Psychotic disorder induced by dissociatives may persist beyond acute intoxication but generally resolves with prolonged abstinence. Primary psychotic disorder presents symptoms that precede substance use, persist during prolonged periods of confirmed abstinence, and frequently include negative symptoms and progressive functional deterioration. Detailed history, observation period during abstinence, and longitudinal assessment are essential for accurate differential diagnosis.

Conclusion: Appropriate coding of disorders due to use of dissociative drugs using ICD-11 code 6C4D requires comprehensive understanding of the clinical characteristics of these substances, specific diagnostic criteria, and careful differentiation from other disorders. Health professionals should remain updated on emerging medical use of ketamine, contemporary patterns of recreational use, and specific complications associated, ensuring accurate documentation that facilitates appropriate treatment and ongoing research in this evolving area.

External References

This article was prepared based on reliable scientific sources:

References verified on 2026-02-03

Disorders due to the use of dissociative drugs, including ketamine and phencyclidine [PCP]

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