2026 ICD-10-CM Diagnosis Code T43.505AAdverse effect of unspecified antipsychotics and neuroleptics, initial encounter

ICD-10-CM Codes›S00–T88›T36-T50›T43

ICD-10-CM T43.505A
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

T43.505A is a billable ICD-10-CM diagnosis code for adverse effect of unspecified antipsychotics and neuroleptics, initial encounter. The 7th character A marks it as an initial encounter code, used while the patient is receiving active treatment. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 917 through 918. The code is not accepted as a principal diagnosis by the Medicare Code Editor. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Adverse effects of drugs and medicaments, initial encounter.

Code Identity

ICD-10-CM Code
T43.505A
Billable Status
Yes — Valid for Submission
Code Describes
Adverse effect of unspecified antipsychotics and neuroleptics, initial encounter
Short Description
Adverse effect of unsp antipsychotics and neuroleptics, init
Parent Code
T43.505
Adverse effect of unspecified antipsychotics and neuroleptics

Code Classification

ChapterS00–T88Injury, poisoning and certain other consequences of external causes
SectionT36-T50Poisoning by, adverse effect of and underdosing of drugs, medicaments and biological substances
CategoryT43Poisoning by, adverse effect of and underdosing of psychotropic drugs, not elsewhere classified
This CodeT43.505AAdverse effect of unspecified antipsychotics and neuroleptics, initial encounter

Code EditsBilling

Medicare Code Editor checks that affect claim validity for T43.505A.

Unacceptable principal diagnosis
There are selected codes that describe a circumstance which influences an individual's health status but not a current illness or injury, or codes that are not specific manifestations but may be due to an underlying cause. These codes are considered unacceptable as a principal diagnosis.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acute akathisia caused by drug
  • Acute akathisia caused by neuroleptic
  • Akathisia
  • Akathisia caused by drug
  • Drug-induced dyskinesia
  • Neuroleptic adverse reaction
  • Neuroleptic malignant syndrome
  • Neuroleptic-induced parkinsonism
  • Neuroleptic-induced tardive dyskinesia
  • Parkinsonism caused by drug
  • Post-injection delirium sedation syndrome
  • Restlessness
  • Subacute dyskinesia caused by drug
  • Tardive dyskinesia

Coding GuidelinesGuidance

When coding an adverse effect of a drug that has been correctly prescribed and properly administered, assign the appropriate code for the nature of the adverse effect followed by the appropriate code for the adverse effect of the drug.

The appropriate 7th character is to be added to each code from block Poisoning by, adverse effect of and underdosing of psychotropic drugs, not elsewhere classified (T43). Use the following options for the applicable episode of care:

  • A - initial encounter
  • D - subsequent encounter
  • S - sequela

Source: ICD-10-CM Official Guidelines for Coding and Reporting, FY 2026, published by CMS and the National Center for Health Statistics.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR INJ028
Adverse effects of drugs and medicaments, initial encounter
Default principal diagnosis: inpatient No · outpatient Yes

Clinical InformationClinical

  • Tardive Dyskinesia

    drug-related movement disorder characterized by uncontrollable movements in certain muscles. it is associated with a long-term exposure to certain neuroleptic medications (e.g., metoclopramide).

  • Neuroleptic Malignant Syndrome

    a potentially fatal syndrome associated primarily with the use of neuroleptic agents (see antipsychotic agents) which are in turn associated with dopaminergic receptor blockade (see receptors, dopamine) in the basal ganglia and hypothalamus, and sympathetic dysregulation. clinical features include diffuse muscle rigidity; tremor; high fever; diaphoresis; labile blood pressure; cognitive dysfunction; and autonomic disturbances. serum cpk level elevation and a leukocytosis may also be present. (from adams et al., principles of neurology, 6th ed, p1199; psychiatr serv 1998 sep;49(9):1163-72)

  • Metoclopramide

    a dopamine d2 antagonist that is used as an antiemetic.

  • Grade 2 Akathisia, CTCAE|Grade 2 Akathisia

    moderate restlessness or increased motor activity; limiting instrumental adl or mild/moderate impact on age-appropriate normal daily activity (pediatric)

  • Grade 3 Akathisia, CTCAE|Grade 3 Akathisia

    severe restlessness or increased motor activity; limiting self-care adl or severe impact on age-appropriate normal daily activity (pediatric)

  • Akathisia

    an uncomfortable feeling of inner restlessness and inability to stay still. it can be a side effect of psychotropic medications.

  • Akathisia, CTCAE|Akathisia|Akathisia

    a disorder characterized by an uncomfortable feeling of inner restlessness and inability to stay still; this is a side effect of some psychotropic drugs.

  • Barnes Akathisia Rating Scale Clinical Classification|BARS|BARS|BARS01

    a standardized rating scale developed by thomas r. e. barnes in 1989 to diagnose akathisia associated with use of antipsychotic agents. this instrument contains objective and subjective sections, as well as a global clinical assessment of akathisia. the first two sections contain a total of 3 items which are rated on a scale of 0 to 3 with 0 being none or normal and 3 being severe. the third section is rated on a 0 to 5 scale with 0 being none and 5 being severe.

  • CDISC Clinical Classification BARS Test Code Terminology|BARS01TC|Barnes Akathisia Rating Scale Clinical Classification Test Code|QS-BARS TESTCD

    test codes of clinical classification questions associated with the barnes akathisia rating scale (bars) for the clinical data interchange standards consortium (cdisc) standard data tabulation model (sdtm).

  • CDISC Clinical Classification BARS Test Name Terminology|BARS01TN|Barnes Akathisia Rating Scale Clinical Classification Test Name|QS-BARS TEST

    test names of clinical classification questions associated with the barnes akathisia rating scale (bars) for the clinical data interchange standards consortium (cdisc) standard data tabulation model (sdtm).

  • Drug-Induced Akathisia|Drug induced akathisia

    evidence of drug-induced akathisia.

  • ESRS-A - Akathisia: Objective|ESRSA1-Akathisia: Objective|ESRSA1-Akathisia: Objective|ESRSA124

    extrapyramidal symptom rating scale-abbreviated (esrs-a) akathisia: objective.

  • ESRS-A - Akathisia: Subjective|ESRSA1-Akathisia: Subjective|ESRSA1-Akathisia: Subjective|ESRSA123

    extrapyramidal symptom rating scale-abbreviated (esrs-a) akathisia: subjective.

  • ESRS-A - CGI-S Akathisia|ESRSA1-CGI-S Akathisia|ESRSA1-CGI-S Akathisia|ESRSA128

    extrapyramidal symptom rating scale-abbreviated (esrs-a) clinical global impression (cgi-s): akathisia.

  • Grade 1 Akathisia, CTCAE|Grade 1 Akathisia

    mild restlessness or increased motor activity

  • Grade 2 Akathisia, CTCAE|Grade 2 Akathisia

    moderate restlessness or increased motor activity; limiting instrumental adl

  • Grade 3 Akathisia, CTCAE|Grade 3 Akathisia

    severe restlessness or increased motor activity; limiting self care adl

Table of Drugs and ChemicalsClinical

Substances in the Table of Drugs and Chemicals that reference this code family. Always confirm in the Tabular List before coding.

SubstanceAccidentalSelf-harmAssaultUndeter­minedAdverse
Effect		Under­dosing
Antianxiety drug NECT43.501T43.502T43.503T43.504T43.505T43.506
AntihallucinogenT43.501T43.502T43.503T43.504T43.505T43.506
Antipsychotic drugT43.501T43.502T43.503T43.504T43.505T43.506
Antipsychotic drug::specified NECT43.501T43.502T43.503T43.504T43.505T43.506
Ataractic drug NECT43.501T43.502T43.503T43.504T43.505T43.506
Neuroleptic drug NECT43.501T43.502T43.503T43.504T43.505T43.506
Tranquilizer NECT43.501T43.502T43.503T43.504T43.505T43.506
Tranquilizer NEC::with hypnotic or sedativeT43.501T43.502T43.503T43.504T43.505T43.506
Tranquilizer NEC::benzodiazepine NECT43.501T43.502T43.503T43.504T43.505T43.506
Tranquilizer NEC::butyrophenone NECT43.501T43.502T43.503T43.504T43.505T43.506
Tranquilizer NEC::carbamateT43.501T43.502T43.503T43.504T43.505T43.506
Tranquilizer NEC::dimethylamineT43.501T43.502T43.503T43.504T43.505T43.506
Tranquilizer NEC::ethylamineT43.501T43.502T43.503T43.504T43.505T43.506
Tranquilizer NEC::hydroxyzineT43.501T43.502T43.503T43.504T43.505T43.506
Tranquilizer NEC::major NECT43.501T43.502T43.503T43.504T43.505T43.506
Tranquilizer NEC::penothiazine NECT43.501T43.502T43.503T43.504T43.505T43.506
Tranquilizer NEC::phenothiazine-basedT43.501T43.502T43.503T43.504T43.505T43.506
Tranquilizer NEC::piperazine NECT43.501T43.502T43.503T43.504T43.505T43.506
Tranquilizer NEC::piperidineT43.501T43.502T43.503T43.504T43.505T43.506
Tranquilizer NEC::propylamineT43.501T43.502T43.503T43.504T43.505T43.506
Tranquilizer NEC::specified NECT43.501T43.502T43.503T43.504T43.505T43.506
Tranquilizer NEC::thioxanthene NECT43.501T43.502T43.503T43.504T43.505T43.506

Patient EducationClinical

Drug Reactions

Most of the time, medicines make our lives better. They reduce aches and pains, fight infections, and control problems such as high blood pressure or diabetes. But medicines can also cause unwanted reactions, such as drug interactions, side effects, and allergies.

The full article covers:

  • What is a drug interaction?
  • What are side effects?
  • What are drug allergies?
  • How can I stay safe when taking medicines?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert T43.505A to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
995.29 Adv eff med/biol NEC/NOS
ApproximateCombination The match is approximate, and more than one code can be needed to describe the source diagnosis. Confirm with contextual judgment.
ICD-9-CM
E939.3 Adv eff antipsychotc NEC
ApproximateCombination The match is approximate, and more than one code can be needed to describe the source diagnosis. Confirm with contextual judgment.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About T43.505AOverview

Is T43.505A a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report adverse effect of unspecified antipsychotics and neuroleptics, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What does the 7th character A in T43.505A mean?

The final character A marks the initial encounter: use it while the patient is receiving active treatment for adverse effect of unspecified antipsychotics and neuroleptics, such as an emergency visit or first evaluation.

What MS-DRG does T43.505A group to?

On inpatient claims, adverse effect of unspecified antipsychotics and neuroleptics, initial encounter maps to MS-DRG 917, 918, with relative weights from 0.8571 to 1.5684 depending on complications. Higher weights mean higher Medicare reimbursement.

Can T43.505A be a principal diagnosis?

No. The Medicare Code Editor rejects this code as a principal diagnosis because adverse effect of unspecified antipsychotics and neuroleptics, initial encounter describes a circumstance that influences health status rather than a current illness. Report it as a secondary diagnosis.

What is the ICD-9 equivalent of T43.505A?

Under the General Equivalence Mappings, adverse effect of unspecified antipsychotics and neuroleptics, initial encounter converts to ICD-9-CM 995.29 (adv eff med/biol NEC/NOS) and E939.3 (adv eff antipsychotc NEC). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.