ICD-10 Code L23.9 – Allergic contact dermatitis, unspecified cause (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code L23.9 – Allergic contact dermatitis, unspecified cause
What it is
This code identifies allergic contact dermatitis when the trigger is not documented or not known. It describes a skin inflammation caused by a delayed hypersensitivity reaction after exposure to an allergen.
Clinical signs
Typical findings include itchy, red, swollen, or blistered skin at the exposure site. Clinical features vary; refer to documentation if the record does not clearly support an allergic pattern.
When to use this code
Use L23.9 when the clinician documents allergic contact dermatitis but does not name the specific cause. It also fits cases where the allergen is suspected yet not confirmed in the note. Code the documented diagnosis, not the presumed irritant or rash type.
Do not use for
Do not use this code for irritant contact dermatitis, atopic dermatitis, or unspecified rash without an allergic contact dermatitis diagnosis. Check documentation if the record names a definite allergen.
Coding tip
If the allergen is identified in the chart, select the more specific allergic contact dermatitis code instead of L23.9.