ICD-10 Code B08.20 – Exanthema subitum [sixth disease], unspecified (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code B08.20 – Exanthema subitum [sixth disease], unspecified
What it is
B08.20 identifies exanthema subitum, also called sixth disease, when the record does not specify a more detailed form. It refers to a viral illness classically associated with a sudden rash after fever.
Clinical signs
Typical documentation includes a brief febrile illness followed by a maculopapular rash, often in a young child. Clinical features vary; refer to documentation.
When to use this code
Use this code when the provider documents exanthema subitum, sixth disease, or roseola, and no further specificity is given. It also fits cases where the chart confirms the diagnosis but does not identify a more detailed subtype. You should code from the provider’s stated diagnosis, not from rash alone.
Do not use for
Do not use this code for an undiagnosed fever with rash, or for other childhood exanthems without documentation of sixth disease. Check documentation if the note names a different viral exanthem.
Coding tip
If the record only describes symptoms, wait for a documented diagnosis before assigning B08.20.