F51.8 vs G47.5
F51.8 and G47.5 can never be reported together. ICD-10-CM declares them mutually exclusive with an Excludes1 note, meaning the two conditions cannot occur in the same patient — so exactly one of them is correct for any given encounter.
The official note, declared on G47.5
parasomnia not due to a substance or known physiological condition (F51.8)
F51.8
Other sleep disorders not due to a substance or known physiological condition
Billable
- Chapter 5
- Mental, Behavioral and Neurodevelopmental disorders
- Section
- F50-F59
Indexed under
- Parasomnia › nonorganic origin
- Disorder › sleep › nonorganic › specified NEC (of)
These two codes sit in different chapters of the Tabular List, which is usually the clearest signal that they describe different underlying processes rather than different degrees of the same one.
Excludes1 is not always absolute: where two conditions covered by the note are genuinely unrelated, CMS guidance permits reporting both. Document the reasoning rather than assuming it. More on Excludes1 vs Excludes2 · FY2027