Crystal's Coder Hub🧬 ICD-10 CM G24.01 — Drug Induced Subacute Dyskinesia
Billable Code Confirmed
ICD-10 CM G24.01 is a valid, fully billable 5-character ICD-10-CM code for FY2026. It is classified under Chapter 6 (Diseases of the Nervous System), within the G20-G26 block covering extrapyramidal and movement disorders, under category G24 (Dystonia) and subcategory G24.0 (Drug induced dystonia). The 5-character code reaches full specificity and is reportable without additional characters. Per the tabular instruction at the G24.0 subcategory level, coders must also assign an additional code from T36-T50 (with fifth or sixth character 5) to identify the causative drug adverse effect.¹²
Non-Billable Parent Codes
ICD-10 CM G24 (Dystonia) is the 3-character parent category — not billable; additional characters are required to reach a reportable level. G24.0 (Drug induced dystonia) is the 4-character subcategory — also not billable; it serves as the parent header for G24.01, G24.02, and G24.09, and must not be submitted on a claim in place of the more specific child codes.¹²
Clinical Context
ICD-10 CM G24.01 specifically captures drug induced subacute dyskinesia, which includes the well-known clinical entity of tardive dyskinesia — involuntary, repetitive movements (orofacial grimacing, tongue thrusting, choreoathetoid limb movements) that develop after prolonged exposure to dopamine receptor-blocking agents, most commonly antipsychotics and certain antiemetics.²⁴ The “subacute” qualifier distinguishes this from G24.02 (Drug induced acute dystonia), which represents an acute, sudden-onset dystonic reaction (e.g., oculogyric crisis, acute torticollis) occurring shortly after drug initiation or dose increase. Coders must carefully review provider documentation and timing of onset to choose between G24.01 and G24.02 — “tardive” by definition implies a delayed, subacute presentation after sustained drug exposure, not an acute reaction.²³
Code Classification
ICD-10 CM G24.01 is a diagnosis code (ICD-10-CM), not a procedure code. It represents a neurological adverse effect of drug therapy — a chronic or subacute movement disorder caused by dopaminergic blockade. It is classified as an extrapyramidal disorder under the diseases of the nervous system chapter and is used for diagnosis reporting on both facility UB-04 and professional CMS-1500 claims.¹
🔍 Code Description
ICD-10 CM G24.01 captures tardive dyskinesia and related drug-induced subacute movement disorders within the ICD-10-CM extrapyramidal disorder framework. Dyskinesia refers to abnormal, involuntary movements that are typically repetitive and purposeless — the “orofacial” subtype (included under this code) involves lip smacking, tongue protrusion, chewing motions, and facial grimacing. The term “subacute” in the code title refers to the clinical course: these movements develop gradually over weeks to months of drug exposure, as opposed to the acute dystonic reactions captured by G24.02. The most common offending agents are first-generation (typical) antipsychotics such as haloperidol and chlorpromazine, though second-generation (atypical) antipsychotics, metoclopramide, and certain antiparkinson agents can also trigger this presentation.²³ Per ICD-10-CM tabular convention, G24.01 must be accompanied by an adverse effect code from the T36-T50 series (fifth or sixth character 5) identifying the specific causative drug — this is a required “use additional code” instruction, not optional.¹²
From an inpatient coding perspective, G24.01 most commonly appears as a secondary diagnosis on psychiatric admissions, particularly in patients with schizophrenia or schizoaffective disorder receiving long-term antipsychotic therapy.²⁵ The condition can also prompt neurological consultations during medical-surgical admissions when previously unrecognized tardive movements are documented by the consulting team. CDI professionals should be alert to provider documentation of “abnormal movements,” “repetitive facial movements,” or “orofacial tics” in patients on chronic antipsychotics — these clinical descriptions may support a G24.01 query if the provider has not yet assigned the diagnosis. Accurate capture of G24.01 alongside the psychiatric diagnosis, applicable adverse effect T-code, and comorbid conditions builds a more complete inpatient clinical picture.²⁵
🌳 Code Tree / Hierarchy
G24 — Dystonia ❌ Non-billable
│
├── G24.0 — Drug induced dystonia ❌ Non-billable (parent)
│ │
│ ├── G24.01 — Drug induced subacute dyskinesia ◀ THIS CODE ✅ Billable
│ │ (Includes: tardive dyskinesia, orofacial dyskinesia, blepharospasm)
│ ├── G24.02 — Drug induced acute dystonia ✅ Billable
│ └── G24.09 — Other drug induced dystonia ✅ Billable
│
├── G24.1 — Genetic torsion dystonia ✅ Billable
│
├── G24.2 — Idiopathic nonfamilial dystonia ✅ Billable
│
├── G24.3 — Spasmodic torticollis ✅ Billable
│
├── G24.4 — Idiopathic orofacial dystonia ✅ Billable
│
├── G24.5 — Blepharospasm ✅ Billable
│
├── G24.8 — Other dystonia ✅ Billable
│
└── G24.9 — Dystonia, unspecified ✅ Billable
Subacute vs. Acute: The Most Critical G24.0x Decision
The distinction between G24.01 and G24.02 hinges entirely on onset timing and clinical pattern. G24.01 (subacute/tardive) = gradual development after weeks-to-months of drug exposure; G24.02 (acute) = sudden-onset dystonia within hours to days of drug initiation or dose increase. Assigning the wrong code misrepresents the clinical severity and duration of drug exposure and can affect treatment authorization (e.g., valbenazine [Ingrezza] or deutetrabenazine [Austedo] are FDA-approved specifically for tardive dyskinesia, not acute dystonia).²³
Required Dual Coding: Don't Forget the T-Code
The G24.0 subcategory carries a mandatory “use additional code” instruction: always pair G24.01 with the appropriate adverse effect code from T36-T50 (fifth or sixth character 5) identifying the causative drug. For example, haloperidol adverse effect = T43.4X5A/D/S (depending on encounter type). Omitting the T-code is a coding error that makes the adverse effect-versus-poisoning distinction impossible to determine from the claim.¹²
✅ Includes
- Tardive dyskinesia: The most clinically recognized entity under G24.01; refers specifically to neuroleptic (antipsychotic)-induced delayed-onset involuntary movements — included explicitly in the ICD-10-CM tabular.¹²
- Neuroleptic induced tardive dyskinesia: The full clinical descriptor mapping this condition to antipsychotic drug exposure; captured under G24.01 per ICD-10-CM includes notes.¹²
- Drug induced orofacial dyskinesia: Involuntary mouth, lip, tongue, and jaw movements induced by dopamine-blocking medications; included under this code and distinct from idiopathic orofacial dystonia (G24.4).¹²
- Drug induced blepharospasm: Involuntary, forceful eyelid closure caused by drug exposure; included under G24.01 and distinct from primary blepharospasm without drug cause (G24.5).¹²
- Subacute movement disorders from antiemetics: Metoclopramide, prochlorperazine, and other dopamine-blocking antiemetics can induce tardive-spectrum dyskinesia; these drug-related presentations are captured under G24.01 with the appropriate T-code for the causative agent.²⁴
❌ Excludes
Excludes 1
There are no Excludes 1 notations directly at the G24.01 code level in FY2026 ICD-10-CM. At the broader G24 category level, there is also no Excludes 1 note. Coders should always confirm current tabular guidance in the annual NCHS ICD-10-CM release.²
Critical Distinctions to Avoid Miscoding Within G24.0x
The most common miscoding error within the G24.0 family is assigning G24.01 when the provider has documented an acute dystonic reaction (e.g., acute torticollis or oculogyric crisis occurring within 24-48 hours of starting a new antipsychotic) — that presentation belongs to G24.02, not G24.01. Conversely, coding G24.02 for a long-standing patient on chronic antipsychotic therapy with tardive orofacial movements is equally incorrect. Review provider documentation for timing, onset pattern, and clinical description before code assignment.²³
Excludes 2
- G80.3 — Athetoid cerebral palsy: Athetoid CP produces similar-appearing involuntary movements but originates from perinatal brain injury rather than drug exposure. Per the Excludes 2 note at the G24 category, G80.3 is separately codeable and may be reported alongside G24.01 in the rare clinical scenario where a patient has both CP and superimposed drug-induced dyskinesia, though such combinations require careful clinical documentation.¹²
📋 Clinical Overview
Drug-Induced Subacute vs. Acute vs. Idiopathic Dyskinesia: Code Selection Guide
Selecting the correct G24.x code requires the coder to match provider documentation to the specific movement disorder pattern and its etiology. The most critical factors are: (1) Was the movement disorder caused by a drug? (2) Was onset acute or gradual/subacute? (3) Is there a non-drug idiopathic etiology instead? The table below summarizes the key differentiators for the most commonly confused codes.²³⁴
| Feature | G24.01 | G24.02 | G24.4 | G24.9 |
|---|---|---|---|---|
| Descriptor | Drug induced subacute dyskinesia | Drug induced acute dystonia | Idiopathic orofacial dystonia | Dystonia, unspecified |
| Drug cause required? | ✅ Yes | ✅ Yes | ❌ No | ❌ Not specified |
| Onset pattern | Gradual — weeks to months of drug exposure | Sudden — hours to days after drug start/dose increase | Gradual idiopathic onset | Not specified |
| Classic presentation | Orofacial grimacing, tongue thrusting, choreoathetoid limbs | Acute torticollis, oculogyric crisis, opisthotonos | Oromandibular dystonia, Meige syndrome | Unspecified involuntary movements |
| T-code required? | ✅ Yes — per tabular instruction | ✅ Yes — per tabular instruction | ❌ No | ❌ No |
| CDI query value | High — drug history must be documented | High — timing and drug initiation must be documented | Moderate | High — query for specificity |
CDI Trigger: Drug History + Movement Disorder Documentation
When a patient on chronic antipsychotic, antiemetic, or dopamine-blocking therapy has any involuntary movement disorder documented, this is a high-priority CDI query opportunity. Providers may document “abnormal movements” or “extrapyramidal symptoms (EPS)” without specifying whether the presentation is acute or subacute/tardive — a targeted query asking the provider to confirm onset timing and whether the movements are consistent with tardive dyskinesia can support G24.01 assignment and ensure the T-code adverse effect is also documented.²⁵
Manifestations & Symptom Burden
- Orofacial dyskinesia: Repetitive lip smacking, tongue protrusion, and chewing movements are the hallmark of tardive dyskinesia; document specifically to support G24.01 over the idiopathic G24.4.²
- Choreoathetoid limb movements: Irregular, writhing limb movements may accompany orofacial involvement in severe tardive dyskinesia; code G24.01 covers this presentation when drug-induced.²³
- Blepharospasm (G24.5 when idiopathic): Drug-induced blepharospasm is included under G24.01; if no drug cause is documented, G24.5 is the appropriate code for primary blepharospasm.¹²
- Respiratory dyskinesia: Rare but severe tardive involvement of respiratory muscles may be documented in complex cases; supports medical necessity for VMAT2 inhibitor therapy and strengthens clinical documentation integrity.²⁴
- Psychiatric comorbidities: Schizophrenia (F20.9), schizoaffective disorder (F25.9), and bipolar disorder (F31.9) are among the most common underlying conditions driving antipsychotic use and subsequent tardive dyskinesia — code each separately per **ICD-10-CM conventions.**²⁵
Manifestation Coding Note
ICD-10 CM G24.01 is an etiology/condition code, not a manifestation code. It does not carry a “code first” instruction and does not require a sequencing note for the dyskinesia itself. However, the causative drug adverse effect T-code is required by the tabular “use additional code” instruction at G24.0- and must be sequenced as an additional code. The psychiatric condition driving the drug use should also be coded separately.¹²
💰 HCC Risk Adjustment
| Model | HCC Mapping | HCC Label | RAF Value |
|---|---|---|---|
| CMS-HCC V28 (PY2026) | ❌ Not Mapped | N/A | 0.000 |
| CMS-HCC V24 | ❌ Not Mapped | N/A | 0.000 |
| RxHCC | ❌ Not Mapped | N/A | 0.000 |
ICD-10 CM G24.01 does not map to any HCC category under either V24 or V28 CMS-HCC risk adjustment models, contributing a RAF value of zero.⁸ As of Payment Year 2026, MA risk adjustment runs exclusively on V28, completing the three-year transition from V24.⁹ While G24.01 carries no direct RAF value, its presence in the record is a strong signal for high-cost coexisting conditions — patients with tardive dyskinesia are almost always on long-term antipsychotics for severe psychiatric illness, and those psychiatric diagnoses (schizophrenia HCC 57, bipolar disorder HCC 58) do carry meaningful RAF weight under V28.⁹ CDI teams should treat G24.01 as a trigger to ensure all underlying psychiatric HCC-mapped diagnoses are fully documented and captured.⁸⁹
🏥 MS-DRG Assignment
| Scenario | MDC | DRG | DRG Title | Relative Weight (approx.) |
|---|---|---|---|---|
| G24.01 as PDX with MCC | MDC 01 | 091 | Other Disorders of Nervous System with MCC | ~2.0 |
| G24.01 as PDX with CC | MDC 01 | 092 | Other Disorders of Nervous System with CC | ~1.2 |
| G24.01 as PDX w/o CC/MCC | MDC 01 | 093 | Other Disorders of Nervous System without CC/MCC | ~0.8 |
| G24.01 as secondary dx | Varies | Determined by PDX | N/A — secondary comorbidity | N/A |
ICD-10 CM G24.01 as the principal diagnosis maps to MDC 01 and falls into the DRG 091-093 family (Other Disorders of Nervous System), with DRG assignment determined by the presence of MCCs or CCs from other secondary diagnoses.⁵ In practice, G24.01 rarely drives inpatient admission as a standalone condition — the patient is far more likely to be admitted for a psychiatric decompensation (DRG 885-887 for psychosis) with tardive dyskinesia as a documented comorbidity. Coders and CDI professionals should note that G24.01 itself is not classified as a CC or MCC, meaning its presence as a secondary diagnosis does not shift DRG weight on its own. Thorough capture of the underlying psychiatric diagnosis, adverse effect T-code, and any true CC/MCC conditions (e.g., aspiration pneumonia, metabolic complications) is essential for accurate DRG optimization.⁵
🔗 Related ICD-10-CM Codes
G24.0x Family — Drug-Induced Dystonia Siblings
- G24.02 — Drug induced acute dystonia: Covers acute-onset dystonic reactions (oculogyric crisis, acute torticollis) occurring shortly after drug initiation — distinguished from G24.01 by onset timing.²³
- G24.09 — Other drug induced dystonia: Use when a drug-induced dystonia is confirmed but does not meet the clinical criteria for either subacute (G24.01) or acute (G24.02) presentations.²
- G24.4 — Idiopathic orofacial dystonia: Captures orofacial dystonia without drug causation; use when no offending agent is documented.¹²
- G24.5 — Blepharospasm (idiopathic): Primary blepharospasm not caused by drug exposure; distinguishable from the drug-induced blepharospasm included under G24.01.¹²
Causative Drug Adverse Effect T-Codes (Required Additional Codes)
- T43.3X5A/D/S — Adverse effect of phenothiazine antipsychotics and neuroleptics (e.g., chlorpromazine, prochlorperazine): One of the most common causative agents for tardive dyskinesia.¹²
- T43.4X5A/D/S — Adverse effect of butyrophenone and thioxanthene neuroleptics (e.g., haloperidol): High-yield T-code for tardive dyskinesia from first-generation antipsychotics; character 5 = adverse effect.¹²
- T43.595A/D/S — Adverse effect of other antipsychotics and neuroleptics (e.g., atypical antipsychotics): Use for second-generation agents (risperidone, olanzapine, quetiapine) causing tardive dyskinesia.¹²
- T45.0X5A/D/S — Adverse effect of antiallergic and antiemetic drugs (e.g., metoclopramide, promethazine): Critical T-code for tardive dyskinesia caused by antiemetic dopamine blockers — a common and frequently undercoded scenario.¹²
🛠️ Commonly Associated CPT Codes
- 99233/99232 — Subsequent hospital care E/M: G24.01 frequently appears as a secondary diagnosis on inpatient subsequent care E/M codes during psychiatric or medical-surgical admissions where the movement disorder is documented and managed.⁵
- 96116 — Neurobehavioral status exam: Ordered when quantifying cognitive or behavioral impact of tardive dyskinesia; supports medical necessity alongside G24.01.²⁴
- 95923 — Testing of autonomic nervous system function: May be ordered in complex movement disorder workups to assess autonomic involvement; pairs with G24.01 in neurology consultations.²
- 90867 — Therapeutic repetitive transcranial magnetic stimulation (TMS) treatment delivery: Emerging off-label use for refractory tardive dyskinesia; G24.01 supports medical necessity documentation for prior authorization, though payer coverage is variable.²⁴
- 99213/99214 — Office/outpatient E/M, established patient: Most common encounter type for ongoing management of tardive dyskinesia with VMAT2 inhibitors (valbenazine, deutetrabenazine) in the outpatient neurology or psychiatry setting.²²
- 90863 — Pharmacologic management (when reported separately): Medication management visits for VMAT2 inhibitor titration and antipsychotic adjustment in tardive dyskinesia management; G24.01 is the supporting diagnosis.²²
NCCI Bundling Considerations
ICD-10 CM G24.01 is a diagnosis code and does not itself trigger NCCI procedure-to-procedure bundling edits; bundling decisions are driven by the CPT codes billed alongside it.² When neurobehavioral testing (96116) is billed with standard E/M codes on the same date by the same provider, NCCI edits may apply — modifier -59 or -96 may be required to separately identify distinct services, and documentation must clearly support the medical necessity of each service.² VMAT2 inhibitor prescriptions (valbenazine, deutetrabenazine) billed under pharmacy or medication management codes should always be supported by documented G24.01 with the corresponding T-code adverse effect to establish drug-induced etiology for payer review and prior authorization.²⁴
🔬 ICD-10-PCS Crosswalk
ICD-10-PCS codes apply to inpatient facility procedure reporting only. The following represent procedures performed in the inpatient setting for patients with G24.01.
- 3E0338Z — Introduction of other therapeutic substance into peripheral vein, percutaneous: Represents IV administration of medications (e.g., benzodiazepines for acute management of dyskinesia-related distress or IV antipsychotic adjustments) in the inpatient setting; G24.01 appears as supporting diagnosis.²
- GZJ0ZZZ — Light therapy: Included for completeness in complex psychiatric inpatient stays; rarely the primary procedure but may appear in multidisciplinary treatment protocols.²
- HZ80ZZZ — Individual counseling for substance use disorder, motivational enhancement: Relevant when substance use complicates antipsychotic management in patients with tardive dyskinesia; G24.01 coded alongside the substance use disorder.²
💊 Coding Scenarios and Examples
Scenario 1: Inpatient Psychiatric Admission with Tardive Dyskinesia as Comorbidity
A 52-year-old male with a 20-year history of schizophrenia is admitted for acute psychotic decompensation after medication non-compliance. During the admission, neurology is consulted for repetitive orofacial movements and tongue thrusting that the patient’s family reports have been progressively worsening over the past year. Neurology documents “tardive dyskinesia secondary to long-term haloperidol therapy.” The patient is restarted on haloperidol with a plan to transition to valbenazine.
Correct Coding:
- F20.9— Schizophrenia, unspecified (PDX — reason for admission after study)
- G24.01 — Drug induced subacute dyskinesia (secondary — tardive dyskinesia)
- T43.4X5D — Adverse effect of butyrophenone neuroleptics, subsequent encounter (haloperidol)
Sequencing: F20.9 is PDX per UHDDS — the psychotic decompensation was the reason for admission. G24.01 is secondary with required T43.4X5D adverse effect code. The “D” (subsequent encounter) 7th character reflects ongoing care.
CDI Note: This is a high-yield documentation scenario. If neurology had only documented “EPS” or “abnormal movements,” a query would be needed to support G24.01. The T-code is mandatory — omitting it is a coding error.¹²⁵
Scenario 2: Antiemetic-Induced Tardive Dyskinesia — Commonly Missed T-Code
A 64-year-old female with a history of chronic nausea managed with long-term metoclopramide is admitted for dehydration and failure to thrive. Neurology documents “orofacial dyskinesia consistent with tardive dyskinesia secondary to chronic metoclopramide use.” The admitting coder assigns G24.01 but omits the causative T-code.
Correct Coding:
- E86.0 — Dehydration (PDX)
- G24.01 — Drug induced subacute dyskinesia
- T45.0X5D — Adverse effect of antiallergic and antiemetic drugs, subsequent encounter (metoclopramide)
Sequencing: E86.0 is PDX. G24.01 is secondary with mandatory T45.0X5D. Metoclopramide-induced tardive dyskinesia is a well-documented but frequently undercoded entity — the FDA added a black box warning to metoclopramide for this risk.
CDI Note: This scenario illustrates why coders must review the medication list and provider documentation together. Long-term metoclopramide is a red flag for tardive dyskinesia risk; a CDI query to the admitting provider about movement disorder documentation may be appropriate during the admission.²⁴
Scenario 3: G24.01 Miscoded as G24.02 — Acute vs. Subacute Error
A 35-year-old female with bipolar I disorder is admitted after starting risperidone three weeks ago. She presents with involuntary lip smacking and subtle choreiform hand movements that have gradually developed over the past two weeks. The provider documents “drug-induced dyskinesia.” The coder incorrectly assigns G24.02 (acute dystonia).
Correct Coding:
- F31.9 — Bipolar disorder, unspecified (PDX)
- G24.01 — Drug induced subacute dyskinesia (not G24.02 — onset is gradual/subacute, not acute)
- T43.595D — Adverse effect of other antipsychotics and neuroleptics, subsequent encounter (risperidone)
Sequencing: F31.9 is PDX. G24.01 is correct because the clinical picture matches subacute/tardive pattern (gradual onset over weeks). G24.02 would only be appropriate if movements had begun acutely within hours-to-days of drug initiation.
CDI Note: When providers document “drug-induced dyskinesia” without specifying acute vs. subacute, a query clarifying the onset timing is warranted before code assignment. This distinction is clinically and coding-ly significant.²³
⚠️ Coding Pitfalls and Tips
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Always Assign the Causative Drug T-Code — It Is Mandatory, Not Optional. The G24.0 subcategory carries an explicit “use additional code” instruction requiring a T36-T50 adverse effect code (fifth or sixth character 5) to identify the causative drug. Submitting G24.01 without the corresponding T-code is a coding error that violates ICD-10-CM Official Guidelines and makes it impossible to determine the adverse effect-versus-poisoning distinction from the claim. Always identify and code the specific drug class using the appropriate T-code with the correct 7th character (A = initial, D = subsequent, S = sequela).¹²
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G24.01 ≠ G24.02: Acute vs. Subacute Onset Is the Entire Distinction. These two sibling codes are frequently confused. G24.01 (subacute/tardive) = gradual onset after prolonged drug exposure (weeks to months); G24.02 (acute) = sudden-onset dystonic reaction within hours to days of drug initiation or dose change. Reviewing the clinical timeline in the provider’s documentation is essential before committing to either code. When documentation is ambiguous, query the provider for clarification — do not assume.²³
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Drug Induced Blepharospasm Is G24.01, NOT G24.5. G24.5 (Blepharospasm) is for idiopathic, non-drug-related blepharospasm. When the provider documents blepharospasm in the context of antipsychotic or other dopamine-blocking drug use, the correct code is G24.01 per the ICD-10-CM includes notes. Assigning G24.5 when drug causation is documented misrepresents the etiology and omits the required T-code pairing.¹²
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Idiopathic Orofacial Dyskinesia vs. Drug-Induced Orofacial Dyskinesia — Don’t Conflate Them. G24.4 (Idiopathic orofacial dystonia) and G24.01 (drug-induced orofacial dyskinesia) can look clinically identical in presentation. The differentiating factor is entirely etiology: is there a documented offending drug? If yes and subacute → G24.01. If no drug cause is documented → G24.4. Coders should not make this determination independently — if documentation is ambiguous, query the provider for drug causation clarification.¹²
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G24.01 Is Not a CC or MCC — Don’t Expect It to Shift DRG Weight. In the MS-DRG system, G24.01 does not qualify as a complicating condition (CC) or major complicating condition (MCC). Its presence as a secondary diagnosis will not improve DRG weight or reimbursement. Inpatient coders should focus secondary diagnosis capture on true CC/MCC conditions coexisting with G24.01 (e.g., aspiration pneumonia, metabolic encephalopathy, sepsis) that do shift DRG assignment.⁵
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Tardive Dyskinesia Is a Signal for High-Cost Psychiatric Comorbidities — Leverage It for CDI. Patients with G24.01 are almost universally on long-term antipsychotics for severe psychiatric illness. Ensure the underlying psychiatric diagnoses (schizophrenia, schizoaffective disorder, bipolar disorder with psychosis) are fully documented and coded, as these carry HCC weight under V28 and significantly impact MA risk scores and DRG assignments on psychiatric DRGs 885-887.⁹⁵