J03.9Acute tonsillitis, unspecified

J03.9 is the ICD-10-CM diagnosis code for acute tonsillitis, unspecified. It belongs to category J03 (acute tonsillitis), block J00-J06 (acute upper respiratory infections) and chapter 10 (diseases of the respiratory system). It is a header code, so it can't be reported by itself; one of its 2 subcodes must be used instead.

Within J03, choose J03.9 (unspecified) only when documentation doesn't support a more specific option: streptococcal tonsillitis (J03.0) and due to other specified organisms (J03.8).

To report this condition, pick the subcode that matches the documentation: J03.90 (unspecified) and J03.91 (unspecified).

Don't report J03.9 together with the conditions in its Excludes1 note: influenza virus with other respiratory manifestations (J09.X2, J10.1, J11.1).

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.