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ICD-10-CM 2027 diagnosis code

R21Rash and other nonspecific skin eruption

✓ Billable / specific

R21 is a valid, billable ICD-10-CM code for rash and other nonspecific skin eruption. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.

Looking up by condition? See ICD-10 code for Rash, ICD-10 code for Skin nonspecific eruption.

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About R21

R21 is the ICD-10-CM diagnosis code for rash and other nonspecific skin eruption. It belongs to block R20-R23 (symptoms and signs involving the skin and subcutaneous tissue) and chapter 18 (symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Don't report R21 together with the conditions in its Excludes1 note: specified type of rash- code to condition and vesicular eruption (R23.8).

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 606 (Minor Skin Disorders with MCC, relative weight 1.5728) and DRG 607 (Minor Skin Disorders without MCC, relative weight 0.8772), in MDC 09 (Diseases and Disorders of the Skin, Subcutaneous Tissue and Breast), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 782.1 (rash and other nonspecific skin eruption).

Coding notes

IncludesFurther defines the content of the category
  • rash NOS
Excludes1Not coded here — never report together with this code
  • specified type of rash- code to condition
  • vesicular eruption (R23.8)

Notes that apply from higher levels

Instructions written at a parent level also apply to R21.

Broader instructions also apply from R20-R23 Symptoms and signs involving the skin and subcutaneous tissue and Chapter 18: Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified.

Alphabetic index entries

4 entries

Terms in the official ICD-10-CM index that lead to R21.

MS-DRG v44.0 grouping

All DRGs →

Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.

MDC 09 · Diseases and Disorders of the Skin, Subcutaneous Tissue and Breast

ICD-9-CM equivalent

Converter →
  • 782.1Rash and other nonspecific skin eruptionexact

From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
  • No changes since FY2016.

Common questions about R21

Is R21 billable?

Yes. R21 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can R21 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict R21 as a principal diagnosis.

Is R21 a CC or MCC?

No. R21 is neither a CC nor an MCC under MS-DRG v44.0.

What DRG does R21 group to?

R21 is used in the MS-DRG v44.0 logic for MS-DRG 606 (Minor Skin Disorders with MCC) and MS-DRG 607 (Minor Skin Disorders without MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.

What is the ICD-9 code for R21?

The CMS General Equivalence Mappings map R21 to ICD-9-CM 782.1.