F28

The F28 diagnosis, according to the ICD-10 classification system, refers to “Other specified psychotic disorder.” It is used when a psychotic disorder is identified but does not meet the criteria for any of the specific psychotic disorders, such as schizophrenia (F20), schizoaffective disorder (F25), or delusional disorder (F22). Instead, it applies to cases that involve psychotic symptoms with unique or atypical features that don’t clearly align with these other conditions. Here is a detailed breakdown of F28.

Core features

1. Psychotic symptoms:
   • These may include delusions, hallucinations, disorganized thinking, or other signs of psychosis.
   • Hallucinations can occur across various sensory modalities (auditory, visual, tactile, etc.).
   • Delusions may be bizarre or non-bizarre, reflecting fixed false beliefs not grounded in reality.
2. Duration:
   • Symptoms may last for a variable period. However, F28 is often applied when the duration does not fully align with the criteria for a specific psychotic disorder (e.g., lasting less than six months for schizophrenia).
3. Atypical presentation:
   • Symptoms may be a mix of psychotic features that do not fit neatly into a single diagnostic category.
   • For instance, elements of schizophrenia, mood disorders, or delusional disorders may coexist without fully meeting the diagnostic threshold for any of them.

Differentiating features

F28 is used as a diagnosis of exclusion. It applies when:

• Psychotic symptoms are present but are not explained by schizophrenia, mood disorders with psychosis, substance-induced psychosis, or medical conditions.
• The presentation is not limited to a specific delusional disorder or another defined psychosis (e.g., postpartum psychosis).

Possible causes and triggers

The causes of an F28 diagnosis are often varied and multifactorial, including:

1. Biological factors:
   • Neurological issues, such as brain injuries or infections.
   • Genetically possible predisposition to any kind of psychotic disorders.
2. Psychosocial factors:
   • Severe stress or trauma.
   • Social isolation or lack of a support system.
3. Substance use:
   • While substance-induced psychosis has its own category (F1x.5), long-term effects of substances or withdrawal could contribute to symptoms that lead to an F28 diagnosis.
4. Medical conditions:
   • Underlying physical illnesses like autoimmune disorders or endocrine abnormalities can indirectly influence psychotic symptoms.

F28 and associated symptoms

• Mood swings or emotional instability (in cases with mood-like features).
• Cognitive difficulties, such as impaired concentration or memory.
• Paranoia or heightened suspicion.
• Difficulty distinguishing reality from imagination.

F28 treatment

Treatment for F28 is individualized due to the heterogeneous nature of the diagnosis:

1. Medication:
   • Antipsychotics (e.g., risperidone, olanzapine) to manage delusions, hallucinations, and disorganized thinking.
   • Mood stabilizers or antidepressants may be added if mood symptoms are present.
2. Therapy:
   • Cognitive-behavioral therapy (CBT) to address thought patterns and improve coping skills.
   • Psychosocial interventions to enhance social functioning and reduce isolation.
3. Support services:
   • Community mental health services.
   • Vocational and occupational therapy for functional recovery.
4. Addressing underlying issues:
   • If a physical or medical condition is contributing to symptoms, treating the underlying issue is crucial.

Prognosis

The outcome for individuals with an F28 diagnosis varies depending on:

• The duration and severity of psychotic symptoms.
• Response to treatment and adherence to interventions.
• Presence of supportive systems, such as family or community support.

In some cases, an F28 diagnosis may eventually be refined into a more specific diagnosis if new information or changes in symptoms occur.

Diagnostic challenges

• The broad and flexible nature of the diagnosis can make it difficult to apply consistently.
• F28 often represents a transitional or provisional diagnosis used until more definitive criteria for another condition are met.

This diagnosis highlights the complexity and variability of psychotic disorders, emphasizing the need for thorough evaluation, ongoing observation, and personalized treatment plans.

Sources

1. World Health Organization (WHO) (1992) The ICD-10 Classification of Mental and Behavioural Disorders: Clinical descriptions and diagnostic guidelines. Geneva: WHO. Available at: https://iris.who.int/bitstream/handle/10665/37958/9241544228_eng.pdf .
2. AAPC (2024) ‘ICD-10-CM Code for Other psychotic disorder not due to a substance or known physiological condition (F28)’. Available at: https://www.aapc.com/codes/icd-10-codes/F28 .
3. ICD Codes AI (2025) ‘Psychotic Disorder – ICD-10 Documentation Guidelines’. Available at: https://icdcodes.ai/diagnosis/psychotic-disorder/documentation .
4. Upvio (2024) ‘F28 ICD Code: Other Nonorganic Psychotic Disorders’. Available at: https://upvio.com/icd-codes/mental-and-behavioural-disorders/f28 .
5. ICD10Data.com (2025) ‘2025 ICD-10-CM Diagnosis Code F28: Other psychotic disorder not due to a substance or known physiological condition’. Available at: https://www.icd10data.com/ICD10CM/Codes/F01-F99/F20-F29/F28-/F28 .
6. WHO (2016) ‘Schizophrenia, schizotypal and delusional disorders (F20-F29)’. Available at: https://icd.who.int/browse10/2016/en .
7. Psychology Town (n.d.) ‘ICD-10 Classification: Schizophrenia and Related Disorders’. Available at: https://psychology.town/mental-disorders/icd-10-schizophrenia-psychotic-disorders/ .
8. SimplePractice (2025) ‘ICD-10 Code F28: Other psychotic disorder not due to a substance or known physiological condition’. Available at: https://www.simplepractice.com/icd-10-codes/f20-f29/f28/ .