Rash and other nonspecific skin eruption
In Symptoms and signs involving the skin and subcutaneous tissue (R20-R23), chapter 18: Symptoms, Signs and Abnormal Clinical and Laboratory Findings
- R21 is billable and valid on claims for FY 2027. If the record has more detail, check the other codes under R20-R23 below.
- As a secondary diagnosis it is not a CC or MCC, so it doesn't raise the MS-DRG payment.
- Doesn't count toward a Medicare Advantage risk score (no HCC in V28).
- AHRQ's Chronic Condition Indicator classes it as not chronic (an acute or short-term condition).
Also indexed as: Eruption, skin; Rash; Rash, rose; Rose, rash
Advertisements
Instructional notes
Includes: conditions that are coded here
- rash NOS
Excludes1: not coded here, use a different code
- specified type of rash- code to condition
- vesicular eruption (R23.8)
Also applies, from Symptoms and signs involving the skin and subcutaneous tissue (R20-R23)
These notes sit on R20-R23 and apply to every code under it, including R21.
Excludes2: not included here, code separately if applicable
- symptoms relating to breast (N64.4-N64.5)
Official coding guidelines
From the ICD-10-CM Official Guidelines for Coding and Reporting, FY 2027 (CMS and NCHS). Links open the PDF at the right page.
Covers when to report symptom, sign, and abnormal finding codes (R00-R99), plus specific rules for falls, coma scales, non-infectious SIRS, death NOS, and NIHSS scores.
- Use of symptom codes (page 75)
- Use of a symptom code with a definitive diagnosis code (page 75)
- Combination codes that include symptoms (page 75)
- Repeated falls (page 76)
- Coma (page 76)
- Functional quadriplegia (page 76)
- SIRS due to Non-Infectious Process (page 77)
- Death NOS (page 77)
Other codes under R20-R23
Symptoms and signs involving the skin and subcutaneous tissue (R20-R23)
- R20Disturbances of skin sensation
- R21Rash and other nonspecific skin eruption(this code)
- R22Localized swelling, mass and lump of skin and subcutaneous tissue
- R23Other skin changes
R21 MS-DRGs
As the principal diagnosis, R21 groups to MS-DRG 606 or 607 (v44.0). Which one applies depends on procedures performed, secondary diagnoses (CC/MCC), and the patient's age and discharge status.
Related conditions
Grouped by AHRQ's Clinical Classifications Software Refined (CCSR), which sorts every diagnosis code into clinically meaningful categories.
R21 is in Skin/Subcutaneous signs and symptoms (SYM014, its default category), with 26 codes. Others in it:
Medicare coverage articles listing R21
These 5 Medicare billing and coding articles list R21 as a diagnosis that supports medical necessity for the services they cover. From the CMS Medicare Coverage Database; check your own contractor's article before billing.
About the condition
Plain-language background from MedlinePlus (National Library of Medicine), not coding guidance.
Rashes
A rash is an area of irritated or swollen skin. Many rashes are itchy, red, painful, and irritated. Some rashes can also lead to blisters or patches of raw skin. Rashes are a symptom of many different medical problems. Other causes include irritating substances and allergies. Certain genes can make people more likely to get rashes.
Read more about rashes on MedlinePlusCode history
Valid since FY2016, when ICD-10-CM took effect on October 1, 2015. No changes since.
ICD-9-CM equivalent
Legacy crosswalk from the CMS General Equivalence Mappings (last updated 2018).
- 782.1 Rash and other nonspecific skin eruption