ICD-10-CM 2027
ICD-10 code for unconsciousness attack
From the official ICD-10-CM alphabetic index entry “Attack, attacks › unconsciousness”. Page updated September 29, 2026.
About coding unconsciousness attack
The ICD-10-CM code for unconsciousness attack is R55 (Syncope and collapse). The official index lists 1 more specific code, so check the documentation for details such as type, cause, site or severity before settling on R55.
Don't report R55 together with the conditions in its Excludes1 note: cardiogenic shock (R57.0), carotid sinus syncope (G90.01), heat syncope (T67.1), neurocirculatory asthenia (F45.8) and 9 more.
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 312 (Syncope and Collapse, relative weight 0.866), in MDC 05 (Diseases and Disorders of the Circulatory System), 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 unconsciousness attack codes (official index)
- hysterical F44.89 — Other dissociative and conversion disorders
Don't confuse with (Excludes1 for R55)
- cardiogenic shock (R57.0)
- carotid sinus syncope (G90.01)
- heat syncope (T67.1)
- neurocirculatory asthenia (F45.8)
- neurogenic orthostatic hypotension (G90.3)
- orthostatic hypotension (I95.1)
- postprocedural shock (T81.1-)
- psychogenic syncope (F48.8)
- shock NOS (R57.9)
- shock complicating or following abortion or ectopic or molar pregnancy (O00-O07, O08.3)
- shock complicating or following labor and delivery (O75.1)
- Stokes-Adams attack (I45.9)
- unconsciousness NOS (R40.2-)
Common questions about unconsciousness attack ICD-10 codes
What is the ICD-10 code for unconsciousness attack?
- R55 — Syncope and collapse. More specific codes apply when the documentation supports them: F44.89.
What is the ICD-10 code for hysterical unconsciousness attack?
- F44.89 — Other dissociative and conversion disorders.
Is R55 billable?
- Yes. R55 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can R55 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict R55 as a principal diagnosis.
Is R55 a CC or MCC?
- No. R55 is neither a CC nor an MCC under MS-DRG v44.0.