R94 vs T88.7
R94 and T88.7 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.
R94
Abnormal results of function studies
Not billable
- Chapter 18
- Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified
- Section
- R90-R94
Use when the record says
- abnormal results of radionuclide [radioisotope] uptake studies
- abnormal results of scintigraphy
T88.7
Unspecified adverse effect of drug or medicament
Not billable
- Chapter 19
- Injury, poisoning and certain other consequences of external causes
- Section
- T80-T88
Use when the record says
- Drug hypersensitivity NOS
- Drug reaction NOS
Indexed under
- Complication › chemotherapyNEC (s) (from) (of)
- Complication › drug NEC (s) (from) (of)
- Damage › medication
- Effect, adverse › drugs and medicaments
- Hypersensitive, hypersensitiveness, hypersensitivity › drug
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