2027 ICD-10-CM Diagnosis Code T43.3X5SAdverse effect of phenothiazine antipsychotics and neuroleptics, sequela
T43.3X5S is a billable ICD-10-CM diagnosis code for adverse effect of phenothiazine antipsychotics and neuroleptics, sequela. The 7th character S marks it as a sequela code, which reports a problem that remains after the original condition has resolved. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 922 through 923. The code is not accepted as a principal diagnosis by the Medicare Code Editor and exempt from POA reporting. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Poisoning/toxic effect/adverse effects/underdosing, sequela.
Code Identity
Code Classification
Code EditsBilling
Medicare Code Editor checks that affect claim validity for T43.3X5S.
Present on Admission (POA)Billing
T43.3X5S is exempt from POA reporting on inpatient claims to general acute care hospitals. Review the other POA exempt codes in Poisoning by, adverse effect of and underdosing of drugs, medicaments and biological substances (T36-T50).
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Alimemazine adverse reaction
- Chlorpromazine adverse reaction
- Chlorpromazine pigmentation
- Drug pigmentation
- Drug-induced pigmentation
- Fluphenazine adverse reaction
- Fluphenazine decanoate adverse reaction
- Fluphenazine enanthate adverse reaction
- Levomepromazine adverse reaction
- Mequitazine adverse reaction
- Pericyazine adverse reaction
- Perphenazine adverse reaction
- Phenothiazine adverse reaction
- Pipothiazine adverse reaction
- Prochlorperazine adverse reaction
- Promazine adverse reaction
- Promethazine adverse reaction
- Retinopathy caused by trifluoperazine
- Thiethylperazine adverse reaction
- Thioridazine adverse reaction
- Thioridazine retinopathy
- Trifluoperazine adverse reaction
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 T43.3X5S: its own notes plus those printed at T43, block T36-T50, and Chapter 19. A note printed at a category, block or chapter applies to every code under it.
Includes
Further defines, or gives examples of, the content of the category.
- adverse effect of correct substance properly administered
- poisoning by overdose of substance
- poisoning by wrong substance given or taken in error
- underdosing by (inadvertently) (deliberately) taking less substance than prescribed or instructed
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
- toxic reaction to local anesthesia in pregnancy (O29.3-)
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
Code First
The underlying condition named in the note is sequenced before this code.
Use Additional Code
Add a second code, after this one, to fully describe the condition.
- code to identify any retained foreign body, if applicable (Z18.-)
Notes
General instructions on how these codes are used.
- Use secondary code(s) from Chapter 20, External causes of morbidity, to indicate cause of injury. Codes within the T section that include the external cause do not require an additional external cause code
- The chapter uses the S-section for coding different types of injuries related to single body regions and the T-section to cover injuries to unspecified body regions as well as poisoning and certain other consequences of external causes.
7th Character
Every code in the category takes a 7th character from the listed values, with the placeholder X filling any empty positions before it.
- The appropriate 7th character is to be added to each code from category T43
- Ainitial encounter
- Dsubsequent encounter
- Ssequela this code
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name T43.3X5S, its category, or a range that includes it.
Excludes1 1
These codes carry an Excludes1 note naming T43.3X5S: they are not reported together with it, unless the two conditions are unrelated.
Use Additional Code 2
These codes say to use an additional code from the note, and T43.3X5S is one of the codes named.
- G21.0 Malignant neuroleptic syndromecode for adverse effect, if applicable, to identify drug (T43.3X5, T43.4X5, T43.505, T43.595) names T43.3X5, which includes this code
- G21.11 Neuroleptic induced parkinsonismcode for adverse effect, if applicable, to identify drug (T43.3X5, T43.4X5, T43.505, T43.595) names T43.3X5, which includes this code
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
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.
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 T43.3X5S to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About T43.3X5SOverview
Is T43.3X5S a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report adverse effect of phenothiazine antipsychotics and neuroleptics, sequela on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What does the 7th character S in T43.3X5S mean?
The final character S makes this a sequela code: it reports a lingering problem that remains after the adverse effect of phenothiazine antipsychotics and neuroleptics itself has resolved, not the original event.
What MS-DRG does T43.3X5S group to?
On inpatient claims, adverse effect of phenothiazine antipsychotics and neuroleptics, sequela maps to MS-DRG 923, 922, with relative weights from 0.9980 to 1.6248 depending on complications. Higher weights mean higher Medicare reimbursement.
Can T43.3X5S be a principal diagnosis?
No. The Medicare Code Editor rejects this code as a principal diagnosis because adverse effect of phenothiazine antipsychotics and neuroleptics, sequela describes a circumstance that influences health status rather than a current illness. Report it as a secondary diagnosis.
Is T43.3X5S exempt from POA reporting?
Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for adverse effect of phenothiazine antipsychotics and neuroleptics, sequela on inpatient claims. The code appears in the Poisoning by, adverse effect of and underdosing of drugs, medicaments and biological substances (T36-T50) range of the CMS exempt list.
