ICD-10 Code L21.9 – Seborrheic dermatitis, unspecified (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code L21.9 – Seborrheic dermatitis, unspecified
What it is
L21.9 identifies seborrheic dermatitis when the site or subtype is not further specified. It is a chronic inflammatory skin condition that commonly affects oily areas such as the scalp, face, and upper trunk.
Clinical signs
Typical findings include erythema with greasy or flaky scale, often with itching or mild irritation. Clinical features vary; refer to documentation if the record does not clearly describe the distribution or severity.
When to use this code
Use L21.9 when the provider documents seborrheic dermatitis but does not specify a more precise form or body location. It also fits when the note confirms the diagnosis yet lacks enough detail for a more specific code. Check documentation if another dermatitis type is mentioned.
Do not use for
Do not assign this code for simple dry skin, psoriasis, atopic dermatitis, or unspecified rash without a documented diagnosis of seborrheic dermatitis. If the condition is localized or otherwise specified, select the more exact code.
Coding tip
Code to the highest documented specificity, and query the provider when seborrheic dermatitis is present but the record also suggests a different dermatitis diagnosis.