ICD-10 Code F59 – Unspecified behavioral syndromes associated with physiological disturbances and physical factors (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code F59 – Unspecified behavioral syndromes associated with physiological disturbances and physical factors
What it is
This code identifies a behavioral syndrome linked to physical or physiological factors, but the record does not specify the exact disorder. Use it when the documentation confirms the syndrome category without naming a more precise diagnosis.
Clinical signs
Clinical features vary; refer to documentation. You may see behavioral changes, emotional disturbance, or other symptoms attributed to an underlying physical condition or physiological disturbance.
When to use this code
Use F59 when the clinician documents an unspecified behavioral syndrome associated with physical or physiological factors and no more specific code is supported. It may apply when the chart links the behavior to a medical condition, but the exact syndrome is not named. Check documentation if the cause or syndrome is clearer elsewhere in the record.
Do not use for
Do not use this code if the record identifies a specific behavioral disorder or a better-defined mental health diagnosis. It is also inappropriate when the symptoms are not linked to physiological disturbances or physical factors.
Coding tip
Code the most specific documented diagnosis first; use F59 only when the provider leaves the syndrome unspecified.