B08.21 Exanthema subitum [sixth disease] due to human herpesvirus 6

Billable ICD-10-CM code, FY2026.

Applicable to

• Roseola infantum due to human herpesvirus 6

Applies from B08 Other viral infections characterized by skin and mucous membrane lesions, not elsewhere classified

Excludes1 (never code together)

• vesicular stomatitis virus disease (A93.8)

Applies from B08.2 Exanthema subitum [sixth disease]

Applicable to

• Roseola infantum

MS-DRG index

Defines the logic of DRG(s) 791 in MDC 15.

Approximate ICD-9-CM (GEMs)

• 058.11 Roseola infantum due to human herpesvirus 6

Medicare Code Edits (MCE v43.1 (April 2026))

• Pediatric diagnoses (age 0 through 17): Age conflict edit. These diagnoses are clinically expected only in patients age 0 through 17.

Code annotations containing back-references to B08.21

Back-references to B08

• Code First: H67 Otitis media in diseases classified elsewhere ("viral disease NEC (B00-B34)")

Diagnosis Index entries for B08.21

• Disease, diseased › sixth › due to human herpesvirus 6
• Exanthem, exanthema › subitum › due to human herpesvirus 6
• Roseola › infantum › due to human herpesvirus 6
• Sixth disease › due to human herpesvirus 6

Nearby codes

• B08.04 Paravaccinia, unspecified
• B08.09 Other orthopoxvirus infections
• B08.1 Molluscum contagiosum
• B08.2 Exanthema subitum [sixth disease]
• B08.20 Exanthema subitum [sixth disease], unspecified
• B08.21 Exanthema subitum [sixth disease] due to human herpesvirus 6 (this code)
• B08.22 Exanthema subitum [sixth disease] due to human herpesvirus 7
• B08.3 Erythema infectiosum [fifth disease]
• B08.4 Enteroviral vesicular stomatitis with exanthem
• B08.5 Enteroviral vesicular pharyngitis
• B08.6 Parapoxvirus infections