Myalgic encephalomyelitis/chronic fatigue syndrome

This diagnosis code represents a complex, chronic, and debilitating neuroimmune condition characterized by profound fatigue that is not alleviated by rest and is worsened by exertion. Patients often experience post-exertional malaise, unrefreshing sleep, cognitive dysfunction, and orthostatic intolerance, significantly impacting their daily functioning.

Use this code for patients formally diagnosed with myalgic encephalomyelitis or chronic fatigue syndrome based on established diagnostic criteria (e.g., Canadian Consensus Criteria, IOM criteria). Documentation should clearly describe the chronic nature of the fatigue, the presence of post-exertional malaise, and other characteristic symptoms that meet diagnostic thresholds.

• Ensure documentation explicitly states a diagnosis of "myalgic encephalomyelitis" or "chronic fatigue syndrome" rather than just "chronic fatigue."
• Do not confuse with codes for generalized fatigue (R53.83) or other specific causes of fatigue, unless ME/CFS is also diagnosed.
• Consider sequencing if other conditions are being treated concurrently; this code often serves as a primary diagnosis when ME/CFS is the focus of the encounter.