ICD-10 Code G21.2 – Secondary parkinsonism due to other external agents (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code G21.2 – Secondary parkinsonism due to other external agents
What it is
This code identifies parkinsonism caused by an external agent, such as a medication, toxin, or other outside exposure. Use it when the record shows a secondary cause rather than idiopathic Parkinson disease.
Clinical signs
Typical findings include tremor, rigidity, bradykinesia, and postural instability. Clinical features vary; refer to documentation, especially when the cause is linked to a drug or toxic exposure.
When to use this code
Use G21.2 when the provider documents secondary parkinsonism due to an external agent and names the cause, if known. This is appropriate when symptoms begin after exposure to a medication, chemical, or other external factor. Code the external cause separately when documentation supports it.
Do not use for
Do not use this code for primary Parkinson disease or when the chart only says “parkinsonism” without a secondary cause. Check documentation if the etiology is unclear.
Coding tip
Confirm the specific external agent in the note and assign any additional codes required for the exposure.