2027 ICD-10-CM Diagnosis Code R21Rash and other nonspecific skin eruption
ICD-10-CM Codes›R00–R99›R20-R23›R21
- Billable — Valid for Submission
- Not Chronic
R21 is a billable ICD-10-CM diagnosis code for rash and other nonspecific skin eruption. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 606 through 607. As a symptom code, it should not be used as a principal diagnosis once a related definitive diagnosis has been established. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Skin/Subcutaneous signs and symptoms.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Acquired pancytopenia
- Acute blistering eruption of skin
- Acute desquamating eruption of skin
- Acute discoid eruption of skin
- Acute eruption of skin
- Acute erythematous eruption of skin
- Acute exudative skin eruption
- Acute maculopapular eruption of skin
- Acute papular eruption of skin
- Acute pustular skin eruption
- Application site rash
- Application site reaction
- Bacteremic skin rash
- Bier anemic spots, cyanosis, and urticaria-like eruption syndrome
- Biers spots
- Blanching of skin
- Blanching rash
- Blisters beneath skin
- Broken skin
- Butterfly rash
- Centrifugal rash
- Centripetal rash
- Disorder of skin co-occurrent with human immunodeficiency virus infection
- Disorder of skin due to human immunodeficiency virus infection
- Eruption
- Eruption of female perineum
- Eruption of skin caused by Salmonella
- Eruption of skin caused by Salmonella Paratyphi
- Eruption of skin caused by Salmonella Paratyphi A
- Eruption of skin caused by Salmonella Paratyphi B
- Eruption of skin caused by Salmonella Paratyphi C
- Eruption of skin co-occurrent with human immunodeficiency virus infection
- Eruption of skin of face
- Eruption of skin of penis
- Eruption of skin present
- Eruption of vulva
- Erythematous rash
- Exanthem caused by Chlamydia psittaci
- Exanthem caused by human echovirus
- Exanthem caused by human echovirus 16
- Generalized rash
- Hemophagocytic lymphohistiocytosis
- Infection of skin caused by Chlamydia
- Introduction procedure site rash
- Localized eruption of skin
- Macular eruption
- Maculopapular eruption
- Micropapular wheal
- Morbilliform eruption
- Multimorphic rash
- Neonatal anemia
- Neonatal disorder of hematopoietic system
- Neonatal thrombocytopenia
- NOCARH syndrome
- Non-blanching rash
- Ornithosis
- Orthostatic intolerance
- Papular eruption
- Papular eruption of blacks
- Papular pruritic eruption of skin due to human immunodeficiency virus infection
- Phototherapy skin rash
- Postural orthostatic tachycardia syndrome
- Premycotic eruption
- Rash due to dribbling from mouth
- Rash due to dribbling of urine
- Rash of genitalia
- Rash of groin
- Rash of periwound skin
- Rash of scalp
- Rash of systemic lupus erythematosus
- Rubelliform eruption
- Skin disorder with AIDS
- Skin rash with AIDS
- Southern tick-associated rash illness
- Synchronous rash
- Vaccination site rash
- Wheal
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to R21: its own notes plus those printed at block R20-R23 and Chapter 18. A note printed at a category, block or chapter applies to every code under it.
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
- specified type of rash- code to condition
- vesicular eruption (R23.8)
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
Notes
General instructions on how these codes are used.
- This chapter includes symptoms, signs, abnormal results of clinical or other investigative procedures, and ill-defined conditions regarding which no diagnosis classifiable elsewhere is recorded.
- Signs and symptoms that point rather definitely to a given diagnosis have been assigned to a category in other chapters of the classification. In general, categories in this chapter include the less well-defined conditions and symptoms that, without the necessary study of the case to establish a final diagnosis, point perhaps equally to two or more diseases or to two or more systems of the body. Practically all categories in the chapter could be designated 'not otherwise specified', 'unknown etiology' or 'transient'. The Alphabetical Index should be consulted to determine which symptoms and signs are to be allocated here and which to other chapters. The residual subcategories, numbered .8, are generally provided for other relevant symptoms that cannot be allocated elsewhere in the classification.
- The conditions and signs or symptoms included in categories R00-R94 consist of:
- (a) cases for which no more specific diagnosis can be made even after all the facts bearing on the case have been investigated;
- (b) signs or symptoms existing at the time of initial encounter that proved to be transient and whose causes could not be determined;
- (c) provisional diagnosis in a patient who failed to return for further investigation or care;
- (d) cases referred elsewhere for investigation or treatment before the diagnosis was made;
- (e) cases in which a more precise diagnosis was not available for any other reason;
- (f) certain symptoms, for which supplementary information is provided, that represent important problems in medical care in their own right.
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Rash (toxic) R21
rose R21
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Exanthema
diseases in which skin eruptions or rashes are a prominent manifestation. classically, six such diseases were described with similar rashes; they were numbered in the order in which they were reported. only the fourth (duke's disease), fifth (erythema infectiosum), and sixth (exanthema subitum) numeric designations survive as occasional synonyms in current terminology.
Patient EducationClinical
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 the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert R21 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About R21Overview
What is the ICD-10 code for rash and other nonspecific skin eruption?
The ICD-10-CM code for rash and other nonspecific skin eruption is R21. It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is R21 (Rash and other nonspecific skin eruption) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report rash and other nonspecific skin eruption on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does R21 group to?
When rash and other nonspecific skin eruption is the principal diagnosis on an inpatient stay, it groups to MS-DRG 607, 606, with relative weights from 0.8772 to 1.5721 depending on complications. Higher weights mean higher Medicare reimbursement.
Can R21 be a principal diagnosis?
Use it with care. This is a symptom code, so once a definitive diagnosis explaining the rash and other nonspecific skin eruption is established, that condition takes the principal position instead.
Can R21 be reported with R23.8?
Not as a rule. The Excludes1 note on R21 lists "vesicular eruption (R23.8)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
