2026 ICD-10-CM Diagnosis Code R21Rash and other nonspecific skin eruption

ICD-10-CM Codes›R00–R99›R20-R23›R21

ICD-10-CM R21
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

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 2026 (October 1, 2025 through September 30, 2026) 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.

Code Identity

ICD-10-CM Code
R21
Billable Status
Yes — Valid for Submission
Code Describes
Rash and other nonspecific skin eruption
Chapter
R20-R23
Symptoms and signs involving the skin and subcutaneous tissue

Code Classification

ChapterR00–R99Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified
SectionR20-R23Symptoms and signs involving the skin and subcutaneous tissue
CategoryR21Rash and other nonspecific skin eruption
This CodeR21Rash and other nonspecific skin eruption

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Includes

  • rash NOS

Type 1 Excludes

  • specified type of rash- code to condition
  • vesicular eruption R23.8

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Eruption
      • skin (nonspecific)
    • Rash(toxic)
    • Rash(toxic)
      • rose
    • Rose
      • rash

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
  • Bullous eruption
  • Butterfly rash
  • Centrifugal rash
  • Centripetal rash
  • Disorder of hematopoietic system in newborn
  • Disorder of skin co-occurrent with human immunodeficiency virus infection
  • 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
  • Eruption of skin caused by Salmonella
  • Eruption of skin caused by Salmonella
  • Eruption of skin caused by Salmonella Paratyphi
  • Eruption of skin caused by Salmonella Paratyphi
  • Eruption of skin caused by Salmonella Paratyphi
  • 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 Chlamydophila psittaci
  • Exanthem caused by human echovirus
  • Exanthem caused by human echovirus 16
  • Generalized rash
  • Hemophagocytic lymphohistiocytosis
  • Localized eruption of skin
  • Macular eruption
  • Maculopapular eruption
  • Micropapular wheal
  • Morbilliform eruption
  • Multimorphic rash
  • Neonatal anemia
  • 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

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR SYM014
Skin/Subcutaneous signs and symptoms
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Postural Orthostatic Tachycardia Syndrome

    a syndrome of orthostatic intolerance combined with excessive upright tachycardia, and usually without associated orthostatic hypotension. all variants have in common an excessively reduced venous return to the heart (central hypovolemia) while upright.

  • Orthostatic Intolerance

    symptoms of cerebral hypoperfusion or autonomic overaction which develop while the subject is standing, but are relieved on recumbency. types of this include neurocardiogenic syncope; postural orthostatic tachycardia syndrome; and neurogenic orthostatic hypotension. (from noseworthy, jh., neurological therapeutics principles and practice, 2007, p2575-2576)

  • Neonatal Alloimmune Thrombocytopenia|NAIT|Neonatal Thrombocytopenia due to Platelet Alloimmunization

    thrombocytopenia that occurs in neonates as a consequence of transplacental passage of maternal alloantibodies directed against fetal platelet antigens.

  • Neonatal Thrombocytopenia

    a condition characterized by a decrease in the number of platelets in the blood below established reference ranges in a newborn.

  • Ornithosis

    disease caused by the chlamydophila psittaci bacteria, usually transmitted from birds to humans.

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.

Nonspecif skin erupt NEC

ICD-9-CM: 782.1

This is a direct match with no additional mapping qualifiers. The absence of a flag generally means the mapping is considered exact or precise. In other words, the ICD-10 code maps cleanly to the ICD-9 code without qualification, approximation, or needing multiple codes.

View Conversion

Code HistoryHistory

  • FY 2026 - No Change, effective from 10/1/2025 through 9/30/2026
  • FY 2025 - No Change, effective from 10/1/2024 through 9/30/2025
  • FY 2024 - No Change, effective from 10/1/2023 through 9/30/2024
  • FY 2023 - No Change, effective from 10/1/2022 through 9/30/2023
  • FY 2022 - No Change, effective from 10/1/2021 through 9/30/2022
  • FY 2021 - No Change, effective from 10/1/2020 through 9/30/2021
  • FY 2020 - No Change, effective from 10/1/2019 through 9/30/2020
  • FY 2019 - No Change, effective from 10/1/2018 through 9/30/2019
  • FY 2018 - No Change, effective from 10/1/2017 through 9/30/2018
  • FY 2017 - No Change, effective from 10/1/2016 through 9/30/2017
  • FY 2016 - New Code, effective from 10/1/2015 through 9/30/2016. This was the first year ICD-10-CM was implemented into the HIPAA code set.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.