ICD-10 Code M04.1 – Periodic fever syndromes (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code M04.1 – Periodic fever syndromes
What it is
M04.1 identifies periodic fever syndromes, a group of disorders marked by repeated episodes of fever without a clear infection. Use it when the record documents a recurrent autoinflammatory fever pattern.
Clinical signs
Typical features include intermittent fever episodes with symptom-free intervals. Clinical features vary; refer to documentation for associated findings such as rash, serositis, joint pain, or oral inflammation.
When to use this code
Use M04.1 when the clinician documents periodic fever syndrome, recurrent unexplained fevers, or a specified autoinflammatory fever disorder classified here. It fits when the diagnosis is established, not just suspected. Check documentation if the note names a specific inherited syndrome.
Do not use for
Do not use this code for fever explained by infection, malignancy, or another defined cause. Do not assign it when the chart only says “fever” or “rule out periodic fever syndrome.”
Coding tip
Look for the exact diagnosed syndrome in the assessment, and code the more specific condition if documented.