G21: Secondary parkinsonism
Codes under G21 (Secondary parkinsonism). A ✓ marks a billable (fully specified) code; category codes without a ✓ are not billable on their own.
| Code | Description | Billable |
|---|---|---|
| G21.0 | Malignant neuroleptic syndrome | ✓ |
| G21.0 | Malignant neuroleptic syndrome | ✓ |
| G21.1 | Other drug-induced secondary parkinsonism | — |
| G21.1 | Other drug-induced secondary parkinsonism | — |
| G21.2 | Secondary parkinsonism due to other external agents | ✓ |
| G21.2 | Secondary parkinsonism due to other external agents | ✓ |
| G21.3 | Postencephalitic parkinsonism | ✓ |
| G21.3 | Postencephalitic parkinsonism | ✓ |
| G21.4 | Vascular parkinsonism | ✓ |
| G21.4 | Vascular parkinsonism | ✓ |
| G21.8 | Other secondary parkinsonism | ✓ |
| G21.8 | Other secondary parkinsonism | ✓ |
| G21.9 | Secondary parkinsonism, unspecified | ✓ |
| G21.9 | Secondary parkinsonism, unspecified | ✓ |
| G21.11 | Neuroleptic induced parkinsonism | ✓ |
| G21.11 | Neuroleptic induced parkinsonism | ✓ |
| G21.19 | Other drug induced secondary parkinsonism | ✓ |
| G21.19 | Other drug induced secondary parkinsonism | ✓ |
Frequently asked questions
What is ICD-10-CM code G21?
G21 is an ICD-10-CM category covering Secondary parkinsonism. It contains 18 more specific diagnosis codes, 16 of which are billable.
Is G21 a billable code?
No — G21 is a category header and isn't billable on its own. Code to the highest level of specificity using one of its subcodes (for example G21.0 — Malignant neuroleptic syndrome). 16 of the 18 codes under G21 are billable.
What codes fall under G21?
G21 includes G21.0, G21.0, G21.1, G21.1, G21.2, plus 13 more. See the full list with descriptions and billable status above.
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Informational only, not coding or medical advice. Verify against the official ICD-10-CM (FY2026) and your payer's guidelines.
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