R21 — Rash and other nonspecific skin eruption
Is R21 billable?
Yes — R21 is billable for FY2027. R21 is a valid, billable ICD-10-CM code at the highest level of specificity in its branch. R21 may be submitted for encounters from October 1, 2026 through September 30, 2027.
R21 at a glance
| Code | R21 |
|---|---|
| Description | Rash and other nonspecific skin eruption |
| Billable | Yes |
| Code set | ICD-10-CM FY2027 |
| Valid for encounters | October 1, 2026 – September 30, 2027 |
Which MS-DRGs does R21 group to?
R21 sits in MDC 09 and helps define the logic of 2 MS-DRGs (version 44, FY2027). Which one a stay actually groups to also depends on procedures and secondary diagnoses.
- 606Minor Skin Disorders with MCCmedical
- 607Minor Skin Disorders without MCCmedical
How is R21 listed in the Alphabetic Index?
These are the routes through the Alphabetic Index that lead to R21. They show the wording a clinician may have documented, which often differs from the Tabular description.
- Rash (toxic)
- Eruption › skin
- Rash › rose (toxic)
- Rose › rash
Excludes1 — never code together
The conditions below can never be reported together with R21 on the same claim. An Excludes1 note means the two conditions cannot occur in the same patient, so reporting both is a coding error.
- specified type of rash- code to condition
- vesicular eruption (R23.8)
Includes
Conditions classified to R21.
- rash NOS
Excludes2 — not included here — inherited from Chapter 18
The conditions below are not part of R21, but a patient may have both at the same time. When documentation supports it, R21 and the excluded code may both be reported.
Excludes2 — not included here — inherited from R20-R23
The conditions below are not part of R21, but a patient may have both at the same time. When documentation supports it, R21 and the excluded code may both be reported.
- symptoms relating to breast (N64.4-N64.5)
How long has R21 existed?
R21 has been in ICD-10-CM since at least FY2016, the earliest fiscal year on record here.
Derived from the official order files for FY2016–FY2026. FY2017 and FY2020 publish no order file, so those years are not covered.
Which codes are confused with R21?
ICD-10-CM declares these codes mutually exclusive with R21 — exactly one of each pair can be correct for a given encounter.