ICD-10 Code B27.80 – Other infectious mononucleosis without complication (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code B27.80 – Other infectious mononucleosis without complication
What it is
B27.80 identifies infectious mononucleosis that is not otherwise specified as a distinct type and has no documented complication. Use it when the record supports mono, but not a more specific EBV-related or complication-based code.
Clinical signs
Typical findings include fever, sore throat, fatigue, and lymphadenopathy. Clinical features vary; refer to documentation for the exact presentation and whether the illness is uncomplicated.
When to use this code
Use this code when the provider documents infectious mononucleosis and does not identify a more specific organism or subtype. It also fits cases described as other infectious mononucleosis without complications. If the note mentions organ involvement, hematologic issues, or other complications, check documentation for a different code.
Do not use for
Do not use this code for infectious mononucleosis with a documented complication or for mononucleosis caused by a more specific agent when another code is supported. Check documentation when the record is unclear.
Coding tip
Code from the provider’s exact wording and confirm that “without complication” is documented before assigning B27.80.