ICD-10 Code G93.31 – Postviral Fatigue Syndrome (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code G93.31 – Postviral fatigue syndrome
What it is
G93.31 identifies postviral fatigue syndrome, a condition marked by prolonged fatigue after a viral illness. It is used when the ongoing weakness and reduced stamina are the main documented problem.
Clinical signs
Typical documentation includes persistent tiredness, reduced exercise tolerance, and symptoms that continue after the acute infection has resolved. Clinical features vary; refer to documentation.
When to use this code
Use G93.31 when the provider documents postviral fatigue syndrome or an equivalent diagnosis and links the fatigue to a prior viral infection. It fits follow-up visits where lingering fatigue remains the primary reason for care. If the record only says “fatigue” without a postviral diagnosis, check documentation.
Do not use for
Do not use this code for fatigue from nonviral causes, such as anemia, depression, or medication effects. It is also not appropriate for nonspecific tiredness without a documented postviral syndrome.
Coding tip
Code only when the provider clearly connects the fatigue to a prior viral illness and documents the syndrome, not just a history of infection.