2027 ICD-10-CM Diagnosis Code T43.505AAdverse effect of unspecified antipsychotics and neuroleptics, initial encounter

ICD-10-CM T43.505A

CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

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 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 791, 793, 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 2027, published by CMS and the National Center for Health Statistics.

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to T43.505A: its own notes plus those printed at T43.5, T43, block T36-T50, and Chapter 19. A note printed at a category, block or chapter applies to every code under it.