ICD-10 Code L21 – Seborrheic dermatitis (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code L21 – Seborrheic dermatitis
What it is
L21 identifies seborrheic dermatitis, an inflammatory skin condition that commonly affects oily areas such as the scalp, face, and upper trunk. It is used when the diagnosis is documented and the condition is not specified more narrowly.
Clinical signs
Typical findings include erythematous, scaly, greasy-appearing patches or plaques, often with dandruff on the scalp. Clinical features vary; refer to documentation if the presentation is atypical or the site is not clear.
When to use this code
Use L21 when the provider documents seborrheic dermatitis, seborrheic eczema, or a similar term without a more specific subtype. It also fits follow-up visits for an established diagnosis when the condition remains active. Confirm the documented body site and any specified variant before coding.
Do not use for
Do not use L21 for simple dry skin, psoriasis, tinea, or other scaly rashes unless seborrheic dermatitis is specifically documented. Check documentation if the note only says “rash” or “dermatitis” without clarification.
Coding tip
Code the documented form and site exactly as written, and use a more specific L21 subcode when the record supports it.