ICD-10 Code F43 – Reaction to severe stress, and adjustment disorders (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code F43 – Reaction to severe stress, and adjustment disorders
What it is
Code F43 covers mental and behavioral conditions that develop after a severe stressor, including adjustment disorders and related stress reactions. It is used when symptoms are tied to a clear stressful event or situation.
Clinical signs
Clinical features vary; refer to documentation. Commonly documented findings include emotional distress, anxiety, depressed mood, sleep disturbance, and difficulty coping after a stressful event.
When to use this code
Use F43 when the record links the patient’s symptoms to a recent or identifiable stressor and the clinician diagnoses a reaction to severe stress or an adjustment disorder. It may apply in outpatient, emergency, or behavioral health settings. Check documentation for the specific subtype.
Do not use for
Do not use F43 for symptoms without a documented stress-related diagnosis or when another mental disorder better explains the presentation. Do not assume causation from stress alone; check documentation.
Coding tip
Capture the stressor and the exact clinician diagnosis, because F43 is broad and documentation often supports a more specific subcode.