ICD-10 Logo
ICDxICD-10 Medical Coding
ICD-10 Logo
ICDxICD-10 Medical Coding
ICD 10 CodesDiagnoses
ICD 10 CodesDiagnoses
ICD-10 Logo
ICDxICD-10 Medical Coding

Comprehensive ICD-10-CM code reference with AI-powered search capabilities.

© 2025 ICD Code Compass. All rights reserved.

Browse

  • All Chapters
  • All Categories
  • Diagnoses

Tools

  • AI Code Search
ICD-10-CM codes are maintained by the CDC and CMS. This tool is for reference purposes only.
v1.0.0
ICD-10 Guide
DiagnosesAllergic Rash

Allergic Rash

ICD-10 Coding for Allergic Rash(L23.9, L23.6, L27.0)

PRIMARY SPECIALTYDermatology
COMPLEXITYHigh
LAST UPDATED09/15/2025
Sam Tuffun, PT, DPT
Physical Therapist | Medical Coding & Billing Contributor

Diagnosis Overview

What is Allergic Rash?
Essential facts and insights about Allergic Rash

Key Clinical Considerations:

  • Presence of erythematous, pruritic rash that may be localized or generalized.
  • Positive patch testing or specific IgE testing indicating an allergic response.
  • Physical examination may reveal vesicles, papules, or urticaria depending on the type of allergic rash.
  • Imaging is typically not required; however, skin biopsy may be performed in atypical cases.
  • Severity can be classified based on the extent of the rash and associated symptoms such as itching or pain.

Clinical Information

Clinical Criteria & Documentation Requirements

  • Document the patient's history of exposure to allergens and previous allergic reactions.
  • Use specific terminology such as 'allergic contact dermatitis' or 'atopic dermatitis' as applicable.
  • Examples include: 'Patient presents with a rash consistent with allergic dermatitis following exposure to poison ivy.'
  • Medical necessity must be established by documenting the impact of the rash on the patient's daily activities.
  • Quality measures may include documentation of patient education regarding allergen avoidance.

Coding Guidelines

Usage Guidelines & Examples

  • Use L23.9 for unspecified allergic contact dermatitis when the specific allergen is unknown.
  • Do not use this code for non-allergic rashes such as irritant contact dermatitis or other dermatological conditions.
  • L23.6 is used for allergic contact dermatitis due to specific agents, while L27.0 is for dermatitis due to unspecified causes.
  • Common errors include using the wrong code for irritant dermatitis; ensure the patient's history supports the allergic diagnosis.
  • In complex cases, consider the patient's full clinical picture and any co-existing conditions that may affect code selection.

Code Exclusions

Important Exclusions

  • Excludes conditions such as irritant contact dermatitis (L24) and other non-allergic skin conditions.
  • Alternative codes for excluded conditions include L24 for irritant dermatitis.
  • Conditions are excluded based on the absence of an allergic mechanism in irritant dermatitis.
  • Common mistakes include misclassifying irritant dermatitis as allergic; ensure thorough patient history.
  • Related but distinct conditions include urticaria and eczema, which may have overlapping symptoms but different etiologies.

Related ICD-10 Codes

Primary Codes
L23.9
Allergic contact dermatitis, unspecified
L23.6
Allergic contact dermatitis due to other specified agents
L27.0
Dermatitis due to unspecified causes
Ancillary Codes
Z77.22
T36-T50
Differential Codes
L24.9
L24.9
for irritant rather than allergic reactions.
L24.6
L24.6
for non-allergic reactions to plants.
L27.1
L27.1
for localized rather than generalized eruptions.

Related CPT Codes

CPT codes will be available in a future update.

Specialty Focus

Primary Specialty

Dermatology

Specialty Applications

  • Applies to patients with known allergies or those presenting with new rashes after exposure to potential allergens.
  • Patient populations include all ages, with increased prevalence in individuals with a history of atopy.
  • Clinical settings include outpatient dermatology clinics, emergency departments, and inpatient care for severe reactions.
  • Specialty-specific applications are relevant in dermatology, allergy/immunology, and primary care.
  • Treatment contexts include management of acute allergic reactions and chronic dermatitis.

Coding Complexity

High Complexity

This diagnosis requires careful attention to:

  • Comprehensive clinical documentation
  • Accurate code selection based on clinical criteria
  • Proper exclusion considerations
  • Specialty-specific coding guidelines

Documentation

Documentation Templates

Template 1

Template: 'Patient diagnosed with allergic rash based on clinical findings of erythema and pruritus.'

Template 2

Template: 'Clinical presentation consistent with allergic dermatitis including vesicular lesions on exposed skin.'

Template 3

Template: 'Diagnostic criteria for allergic contact dermatitis met as evidenced by positive patch test results.'

Template 4

Template: 'Treatment plan initiated for allergic rash with topical corticosteroids and antihistamines.'

Template 5

Template: 'Follow-up care for allergic dermatitis including monitoring for recurrence and allergen avoidance strategies.'

Billing Information

Billing Considerations

  • Ensure proper documentation for billing
  • Verify code specificity requirements
  • Check for any additional codes needed
  • Review payer-specific guidelines

Common Issues

  • Insufficient clinical documentation
  • Incorrect code selection
  • Missing supporting diagnoses
  • Timing and frequency documentation

Frequently Asked Questions

What documentation is required for this diagnosis?

Detailed documentation of patient history, exposure, and clinical findings is essential.

How does this differ from similar diagnoses?

Allergic rash is specifically triggered by allergens, while irritant dermatitis is due to non-allergic irritants.

What are common billing considerations?

Ensure that the diagnosis is supported by clinical findings and that medical necessity is documented.

What procedures are typically associated?

Related CPT codes may include skin patch testing and allergy testing procedures.

Are there any quality reporting implications?

Quality measures may include documentation of patient education and follow-up care plans.