ICD-10 Code A08.1 – Acute gastroenteropathy due to Norwalk agent and other small round viruses (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code A08.1 – Acute gastroenteropathy due to Norwalk agent and other small round viruses
What it is
A08.1 identifies acute gastroenteritis caused by Norwalk agent and similar small round viruses, commonly called norovirus. Use it for an acute infectious stomach and intestinal illness documented as due to these viruses.
Clinical signs
Typical features include sudden nausea, vomiting, diarrhea, abdominal cramping, and sometimes low-grade fever. Clinical features vary; refer to documentation for the confirmed viral cause and whether the illness is described as acute gastroenteropathy.
When to use this code
Use this code when the provider documents norovirus, Norwalk agent, or other small round virus as the cause of acute gastroenteritis. It also fits charted cases of acute gastroenteropathy with that viral attribution. If the organism is not specified, check documentation before assigning A08.1.
Do not use for
Do not use A08.1 for gastroenteritis from bacteria, parasites, toxins, or noninfectious causes. If the record only says vomiting or diarrhea without a documented viral cause, check documentation.
Coding tip
Look for the specific viral wording in the assessment, not just symptoms, before you code A08.1.