ICD 10 code for delirium

The ICD 10 code for delirium is used to address one of the most clinically urgent and frequently misunderstood neuropsychiatric conditions encountered in medical and behavioral health settings.

Summary

• Delirium (ICD-10-CM F05) is an acute, fluctuating disturbance in attention and cognition that requires urgent medical evaluation and careful documentation.
• It is usually secondary to a medical, neurological, or substance-related cause, not a primary psychiatric disorder.
• Using an accurate ICD 10 code for delirium (F05, F05.0, F05.9) supports medical necessity, interdisciplinary communication, and client safety. Enrolling in an insurance billing course for therapists can help providers enhance their knowledge.
• Mental health clinicians play a key role in recognizing symptoms, initiating referral, documenting clearly, and supporting families, even when they are not the diagnosing medical provider. By leveraging an EHR like TheraPlatform for efficient documentation and claim submission, therapists can tackle billing with ease.

For therapists, social workers, and other mental health professionals, understanding how delirium is diagnosed and coded is essential for appropriate documentation, interdisciplinary communication, and client safety.

In ICD 10 code for delirium is primarily F05, with additional specification codes depending on presentation and etiology. While delirium often originates from medical or substance-related causes, mental health providers are frequently involved in assessment, consultation, or follow-up care.

A clear understanding of this diagnosis ensures accurate documentation and appropriate referral when necessary.

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What is delirium?

Delirium is an acute disturbance in attention, awareness, and cognition that develops over a short period of time, typically hours to days. Unlike many psychiatric disorders that evolve gradually, delirium represents a rapid change from baseline functioning and tends to fluctuate throughout the day.

The core clinical feature of delirium is impaired attention. Clients may have difficulty sustaining focus, following conversations, or shifting attention appropriately. They may appear easily distracted, confused, or disoriented. In more severe cases, individuals may not recognize familiar people or environments.

In addition to attention deficits, delirium often includes changes in cognition, such as:

• Memory impairment
• Disorientation to time or place
• Language disturbances
• Perceptual disturbances such as hallucinations
• Disorganized thinking

Sleep-wake cycle disruption is also common. Clients may be awake and agitated at night but drowsy during the day. Psychomotor changes may occur, presenting either as agitation and restlessness or slowed, lethargic behavior.

It is important to distinguish delirium from dementia and primary psychiatric disorders. Dementia typically develops gradually and is progressive. Delirium, by contrast, is acute and often reversible when the underlying cause is treated.

Mood disorders, psychosis, or anxiety may mimic aspects of delirium, but they do not usually produce the fluctuating consciousness and attention deficits characteristic of this condition.

Clinically, delirium is considered a medical emergency. It often signals an underlying physiological disturbance requiring prompt evaluation.

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Common causes: Medical, neurological, substance-related

Delirium is not a standalone psychiatric condition in most cases. It is usually secondary to an underlying medical, neurological, or substance-related issue. Identifying the cause is critical for effective treatment.

Medical causes

Medical conditions are among the most common triggers of delirium. Infections such as urinary tract infections, pneumonia, or sepsis frequently precipitate delirium, particularly in older adults. Fever, inflammation, and metabolic disturbances can all affect brain functioning.

Other medical contributors include:

• Electrolyte imbalances
• Hypoxia
• Dehydration
• Liver or kidney failure
• Endocrine disorders such as thyroid dysfunction
• Postoperative complications

Hospitalized individuals, especially those in intensive care units, are at elevated risk. Advanced age, polypharmacy, and preexisting cognitive impairment increase vulnerability.

Neurological causes

Neurological events can directly disrupt brain functioning and lead to delirium. These include:

• Stroke
• Traumatic brain injury
• Seizure disorders
• Brain tumors
• Central nervous system infections

In these cases, delirium may present alongside focal neurological symptoms, but not always. Subtle cognitive changes may be the first sign of a serious neurological event.

Substance-related causes

Substances are a significant contributor to delirium. This includes both intoxication and withdrawal states.

Alcohol withdrawal delirium, commonly referred to as delirium tremens, is a well-known and potentially life-threatening example. Benzodiazepine withdrawal can also produce severe cognitive disturbance.

Other substance-related causes include:

• Medication side effects
• Polypharmacy interactions
• Sedatives
• Anticholinergic medications
• Opioids
• Illicit substances

Even therapeutic medications can contribute to delirium, particularly in medically vulnerable individuals.

For mental health clinicians, it is necessary to assess for recent medication changes, substance use, or withdrawal symptoms when clients present with sudden confusion or altered cognition.

ICD 10 Code for delirium details: F05, F05.0, F05.9

Using the most accurate ICD-10 code for delirium supports medical necessity, continuity of care, and appropriate reimbursement. Delirium falls under Category F05, which is classified as delirium due to a known physiological condition.

F05 Delirium due to a known physiological condition

The base ICD 10 code for delirium, F05 applies when delirium is directly attributable to a medical condition. Documentation must support that the cognitive disturbance is not better explained by another neurocognitive disorder and that there is evidence linking the symptoms to a physiological cause.

Clinicians should document:

• Acute onset and fluctuating course
• Disturbance in attention and awareness
• Additional cognitive disturbance
• Evidence of an underlying medical cause

F05.0 Delirium not superimposed on dementia

F05.0 is used when delirium occurs in a person without preexisting dementia. This distinction matters because delirium may also occur in individuals who already have a major neurocognitive disorder.

Clear documentation that the client did not have prior dementia supports the use of F05.0.

F05.9 Delirium, Unspecified

The F05.9 ICD 10 code for delirium is used when there is insufficient information to determine the specific etiology or when documentation does not clarify whether dementia is present.

While unspecified codes may be appropriate in emergency or early evaluation contexts, clinicians should update diagnoses once additional medical information becomes available.

Differentiating from related codes

Delirium should not be confused with:

• F03.90 Unspecified dementia without behavioral disturbance
• F06.0 Psychotic disorder due to known physiological condition
• F10.231 Alcohol withdrawal delirium

Using the correct ICE 10 code for delirium requires careful assessment of cause and symptom presentation. Collaboration with medical providers is often necessary.

Treatment and documentation tips

Because delirium is usually secondary to an underlying condition, treatment focuses primarily on addressing the medical cause. Mental health professionals often play a supportive, consultative, or follow-up role.

Immediate clinical priorities

If delirium is suspected, referral for urgent medical evaluation is critical. This is especially true when symptoms include sudden confusion, hallucinations, severe agitation, or decreased consciousness.

Mental health clinicians should avoid assuming that acute confusion represents anxiety, depression, or psychosis without medical assessment.

Environmental and supportive interventions

While the medical team addresses the physiological cause, environmental interventions can reduce distress and promote stabilization.

Helpful strategies include:

• Providing orientation cues such as clocks and calendars
• Ensuring adequate lighting
• Minimizing overstimulation
• Encouraging family presence when appropriate
• Supporting regular sleep-wake cycles

Calm reassurance and simple communication are essential. Clients experiencing delirium may be frightened or paranoid due to perceptual disturbances.

Psychotherapy considerations

Traditional psychotherapy is generally not appropriate during acute delirium because cognitive impairment limits insight and engagement. However, therapists may support families, assist with safety planning, or provide short-term stabilization.

After delirium resolves, clients may benefit from therapy to process the experience, particularly if hospitalization or ICU care was traumatic.

Documentation best practices

Documentation should clearly reflect:

• Sudden onset and fluctuating course
• Observed attention deficits
• Cognitive disturbances
• Referral for medical evaluation
• Collaboration with medical providers

Avoid vague statements such as “client seemed confused.” Instead, describe specific behaviors such as inability to maintain conversation, disorientation to date, or fluctuating alertness.

If you are not the diagnosing medical provider but are documenting observed delirium symptoms, clearly state that symptoms are suspected to be medically related and that referral was made.

Risk and liability considerations

Failure to recognize delirium can have serious consequences. Because delirium often indicates medical instability, missing the diagnosis may delay life-saving care.

When in doubt, err on the side of medical referral. Thorough documentation of assessment and referral protects both client safety and professional liability.

Delirium is a serious but often reversible condition that requires prompt recognition and intervention. For therapists and behavioral health clinicians, understanding the ICD 10 code for delirium, F05, and its related specifications supports accurate documentation and effective interdisciplinary communication.

Although delirium originates from medical or substance-related causes, mental health professionals often play an important role in identifying symptoms, supporting families, and ensuring appropriate referral.

Accurate coding is not merely administrative. It reflects clinical clarity, protects client safety, and strengthens collaboration across care settings. By recognizing the signs of delirium and documenting carefully, therapists contribute meaningfully to comprehensive, ethical care.

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How EHR and practice management software can save you time with insurance billing for therapists

EHRs with integrated billing software and clearing houses, such as TheraPlatform, offer therapists significant advantages in creating an efficient insurance billing process. The key is minimizing the amount of time dedicated to developing, sending, and tracking medical claims through features such as automation and batching. 

What are automation and batching?

• Automation refers to setting up software to perform tasks with limited human interaction.
• Batching or performing administrative tasks in blocks of time at once allows you to perform a task from a single entry point with less clicking.

Which billing and medical claim tasks can be automated and batched through billing software?

• Invoices: Create multiple invoices for multiple clients with a click or two of a button or set up auto-invoice creation, and the software will automatically create invoices for you at the preferred time. You can even have the system automatically send invoices to your clients.
• Credit card processing: Charge multiple clients with a click of a button or set up auto credit card billing, and the billing software will automatically charge the card (easier than swiping!)
• Email payment reminders: Never manually send another reminder email for payment again, or skip this altogether by enabling auto credit card charges.  
• Automated claim creation and submission: Batch multiple claims with one button click or turn auto claim creation and submission on. 
• Live claim validation: The system reviews each claim to catch any human errors before submission, saving you time and reducing rejected claims. 
• Automated payment posting: Streamline posting procedures for paid medical claims with ERA. When insurance offers ERA, all their payments will post automatically on TheraPlatform's EHR.
• Tracking: Track payment and profits, including aging invoices, overdue invoices, transactions, billed services, service providers 

Utilizing billing software integrated with an EHR and practice management software can make storing and sharing billing and insurance easy and save providers time when it comes to insurance billing for therapists.

Resources for mental health therapists

Theraplatform is an all-in-one EHR, practice management and teletherapy solution with AI-powered notes and Wiley Treatment Planners that allow you to focus more on patient care. With a 30-day free trial, you have the opportunity to experience Theraplatform for yourself with no credit card required. Cancel anytime. They also support different industries including mental and behavioral health therapists in group practices and solo practices.

More resources

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• The Ultimate Insurance Billing Guide for Therapists
• The Ultimate Guide to Starting a Private Therapy Practice
• Insurance billing 101
• Practice management tools

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References

American Psychiatric Association. (2022). Diagnostic and statistical manual of mental disorders (5th ed., text rev.; DSM-5-TR).

Faeder, M., Hale, E., Hedayati, D., Israel, A., Moschenross, D., Peterson, M., Peterson, R., Piechowicz, M., Punzi, J., & Gopalan, P. (2023). Preventing and treating delirium in clinical settings for older adults. Therapeutic Advances in Psychopharmacology, 13(13). https://doi.org/10.1177/20451253231198462. https://journals.sagepub.com/doi/10.1177/20451253231198462

‌Seunghee, E. (2023). Delirium. Www.hopkinsmedicine.org. https://www.hopkinsmedicine.org/health/conditions-and-diseases/delirium

National Institute for Health and Care Excellence. (2023). Delirium: Prevention, diagnosis and management (NICE Guideline CG103). https://www.nice.org.uk/Guidance/CG103

Centers for Disease Control and Prevention. (2024). ICD-10-CM Official Guidelines for Coding and Reporting. https://icd.who.int/browse10/2019/en