G21.0 – Malignant neuroleptic syndrome

ICD-10-CM 2027 diagnosis code · Extrapyramidal and movement disorders

Billable code

ICD-10-CM code G21.0

Code: G21.0 (claims format: G210)
Description: Malignant neuroleptic syndrome
Billable: Yes – valid for HIPAA-covered transactions
Valid for: Dates of service October 1, 2026 – September 30, 2027 (FY2027)
Chapter: 6. Diseases of the nervous system (G00-G99)
Block: G20-G26 Extrapyramidal and movement disorders
Parent codes: G21

Notes for G21.0

Excludes1 (not coded here):

neuroleptic induced parkinsonism (G21.11)

Use additional code:

code for adverse effect, if applicable, to identify drug (T43.3X5, T43.4X5, T43.505, T43.595)

Notes inherited from parent codes

Instructional notes at a category or block level apply to every code below it.

G21 – Secondary parkinsonism

Excludes1 (not coded here):

Huntington's disease (G10)
neurocognitive disorder with Lewy bodies (G31.83)
Shy-Drager syndrome (G90.3)
syphilitic Parkinsonism (A52.19)

Index terms for G21.0

Entries in the ICD-10-CM alphabetic index that lead to this code:

Syndrome, malignant, neuroleptic

Related codes in G21

G21.1 – Other drug-induced secondary parkinsonismHeader
G21.2 – Secondary parkinsonism due to other external agentsBillable
G21.3 – Postencephalitic parkinsonismBillable
G21.4 – Vascular parkinsonismBillable
G21.8 – Other secondary parkinsonismBillable
G21.9 – Secondary parkinsonism, unspecifiedBillable

Frequently asked questions

What is ICD-10 code G21.0?

G21.0 is the ICD-10-CM code for malignant neuroleptic syndrome, in the block G20-G26 (Extrapyramidal and movement disorders).

Is G21.0 a billable code?

Yes. G21.0 is a billable/specific code that can be used to indicate a diagnosis for reimbursement purposes.

What category does G21.0 belong to?

It belongs to category G21 – Secondary parkinsonism.

Source: CDC/NCHS ICD-10-CM FY2027 code files, tabular list and index. Reference only – code assignment must follow the official ICD-10-CM guidelines and documentation in the medical record.