G21Header code — not billable
Secondary parkinsonism
- Chapter
- 6. Diseases of the nervous system
- Category
- G21
- Effective date
- October 1, 2026
Related codes in category G21
G21.0Malignant neuroleptic syndromeYesG21.1Other drug-induced secondary parkinsonismG21.11Neuroleptic induced parkinsonismYesG21.19Other drug induced secondary parkinsonismYesG21.2Secondary parkinsonism due to other external agentsYesG21.3Postencephalitic parkinsonismYesG21.4Vascular parkinsonismYesG21.8Other secondary parkinsonismYesG21.9Secondary parkinsonism, unspecifiedYes
Frequently asked questions
What is ICD-10 code G21?
G21 is an ICD-10-CM diagnosis code for Secondary parkinsonism.
Is G21 a billable code?
No. G21 is a category/header code, not billable on its own — use one of its more specific child codes instead.
What ICD-10-CM chapter is G21 in?
G21 falls under Chapter 6: Diseases of the nervous system.
When did G21 become effective?
G21 has been effective since October 1, 2026, per the CMS/CDC ICD-10-CM annual release.
What other codes are related to G21?
G21 belongs to category G21, which includes 9 other codes — see the related codes list on this page.
ICD-10-CM data maintained by CDC/CMS (public domain). Always verify codes with authoritative sources before making coding or billing decisions.