ICD-10-CM 2027
ICD-10 code for fear reaction
From the official ICD-10-CM alphabetic index entry “Reaction › fear”. Page updated September 29, 2026.
About coding fear reaction
The ICD-10-CM code for fear reaction is F40.9 (Phobic anxiety disorder, unspecified). The official index lists 1 more specific code, so check the documentation for details such as type, cause, site or severity before settling on F40.9.
Within F40, choose F40.9 (Phobic anxiety disorder, unspecified) only when documentation doesn't support a more specific option: agoraphobia (F40.0), social phobias (F40.1), specific (isolated) phobias (F40.2) and other phobic anxiety disorders (F40.8).
It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.
In MS-DRG v44.0, it is part of the grouping logic for DRG 882 (Neuroses Except Depressive, relative weight 0.9952), in MDC 19 (Mental Diseases and Disorders), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
More specific fear reaction codes (official index)
- child (abnormal) F93.8 — Other childhood emotional disorders
Common questions about fear reaction ICD-10 codes
What is the ICD-10 code for fear reaction?
- F40.9 — Phobic anxiety disorder, unspecified. More specific codes apply when the documentation supports them: F93.8.
What is the ICD-10 code for child fear reaction?
- F93.8 — Other childhood emotional disorders.
Is F40.9 billable?
- Yes. F40.9 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can F40.9 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict F40.9 as a principal diagnosis.
Is F40.9 a CC or MCC?
- No. F40.9 is neither a CC nor an MCC under MS-DRG v44.0.