ICD-10 Code G93.39 – Other Post Infection and Related Fatigue Syndromes (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code G93.39 – Other post infection and related fatigue syndromes
What it is
G93.39 identifies fatigue syndromes that follow an infection or a related illness pattern but are not otherwise classified. Use it for persistent, unexplained fatigue when the documentation supports a post-infectious syndrome.
Clinical signs
Clinical features vary; refer to documentation. Commonly recorded findings include prolonged fatigue, reduced activity tolerance, and symptoms that continue after the acute infection has resolved.
When to use this code
Use this code when the provider documents a post-infection fatigue syndrome or a similar related fatigue condition and no more specific diagnosis is given. It may fit follow-up visits for ongoing fatigue after an infectious illness. Code only what is documented; check documentation if the record is vague.
Do not use for
Do not use it for ordinary tiredness, nonspecific weakness, or fatigue with a clearly documented alternate cause. Do not assign it when the record supports another specific neurologic or systemic diagnosis.
Coding tip
Confirm that the chart links the fatigue to a post-infectious syndrome before assigning G93.39.