ICD-10 R21
Billable / SpecificRash and other nonspecific skin eruption
About ICD-10-CM R21
ICD-10-CM code R21 represents Rash and other nonspecific skin eruption. This is a billable/specific code in the Symptoms, Signs, and Abnormal Findings chapter (block R21). The 2026 edition of ICD-10-CM R21 became effective on October 1, 2025.
Type 1 Excludes
Pure excludes, these codes can never be coded together with R21. The conditions are mutually exclusive (e.g., congenital vs acquired forms).
- specified type of rash- code to condition
- vesicular eruption (R23.8)
Includes
- rash NOS
Medicare LCD Coverage for R21
Local Coverage Determinations (LCDs) from CMS MACs that list R21 as a covered diagnosis.
Showing top 10 of 507 total . Click a CPT for full coverage scope.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing R21.
1 Cigna
5 Medicare
CPT Codes Commonly Billed with R21
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
- 99202 New patient office visit — fever, headache, abdominal pain, cough, dyspnea, fatigue, dizziness, limb pain, nausea, routine exam, URI, UTI, pharyngitis, otitis, chest pain, weight loss Primary Care
- 99212 Established patient — URI, UTI, pharyngitis, otitis, dermatitis, rash, viral infection, cellulitis, conjunctivitis, sinusitis, bronchitis, ankle sprain Primary Care
- 11102 Tangential skin biopsy — uncertain neoplasm skin, actinic keratosis, melanocytic nevi, skin cancer, melanoma, psoriasis, discoid lupus, skin disorder, rash, seborrheic keratosis, benign neoplasm, dermatitis, prurigo, dermatitis herpetiformis Dermatology
Convert R21 to ICD-9-CM
Per CMS General Equivalence Mappings (GEMs), useful for legacy data review and historical claim analysis.
| ICD-10 | ICD-9 | Mapping Flags |
|---|---|---|
| R21 | 7821 | 00000 |
Flags format (5 digits): Approximate · No Map · Combination · Scenario · Choice List. Source: CMS 2017 GEMs (final version).
Codes Adjacent To R21
Other codes in section R20-R23 (Symptoms and signs involving the skin and subcutaneous tissue).
ICD-10 R21, Billing FAQ
Is ICD-10 code R21 billable? +
Yes, R21 is a billable ICD-10-CM code that can appear as a primary or secondary diagnosis on claims.
What codes are Type 1 Excludes for R21? +
Type 1 Excludes (never code together with R21): specified type of rash- code to condition; vesicular eruption (R23.8)
What CPT codes are commonly billed with R21? +
Procedures frequently paired with R21 include: 99202, 99212, 11102.
What ICD-9 codes does R21 map to? +
Per CMS GEMs, R21 maps to ICD-9 codes: 7821. Useful for legacy data review and historical claim analysis.
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Reviewed by the PayerReady Medical Coding Team
Verified against the CMS 2026 code set on July 17, 2026.
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