ICD-10 Code F05 – Delirium due to known physiological condition (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code F05 – Delirium due to known physiological condition
What it is
F05 identifies delirium caused by an underlying medical or physiologic condition. Use it when the record shows an acute disturbance in attention and awareness linked to a known cause.
Clinical signs
Typical findings include sudden confusion, reduced attention, disorientation, and fluctuating mental status. Clinical features vary; refer to documentation for the specific cause and severity.
When to use this code
Use F05 when the provider documents delirium due to infection, metabolic disturbance, medication effect, or another known physiologic condition. It applies when the delirium is the coded diagnosis and the cause is identified in the chart.
Code the underlying condition as well when documented. If the note only says altered mental status or confusion without delirium, check documentation before assigning F05.
Do not use for
Do not use F05 for dementia, psychosis, or simple disorientation without delirium. Do not assign it when the cause is unknown or not documented.
Coding tip
Confirm that the provider explicitly links delirium to a known physiologic condition before coding F05.