2027 ICD-10-CM Diagnosis Code T42.0X2SPoisoning by hydantoin derivatives, intentional self-harm, sequela

ICD-10-CM T42.0X2S

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

T42.0X2S is a billable ICD-10-CM diagnosis code for poisoning by hydantoin derivatives, intentional self-harm, 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 exempt from POA reporting. Coders also document this condition as hydantoin derivative poisoning. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Mental and substance use disorders; sequela; and Poisoning/toxic effect/adverse effects/underdosing, sequela.

T42.0X2S no longer risk-adjusts for Medicare Advantage: it mapped to HCC 59 under the retired CMS-HCC V24 model through payment year 2025 but maps to no category in the live V28 model. It still risk-adjusts in the PACE (CMS-HCC V22) category 58, ESRD (V21) category 58, and ESRD (V24) category 59 for payment year 2027.

Code Identity

ICD-10-CM Code

T42.0X2S

Billable Status

Yes — Valid for Submission

Code Describes

Poisoning by hydantoin derivatives, intentional self-harm, sequela

Short Description

Poisoning by hydantoin derivatives, self-harm, sequela

Parent Code

T42.0X2

Poisoning by hydantoin derivatives, intentional self-harm

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

CategoryT42Poisoning by, adverse effect of and underdosing of antiepileptic, sedative- hypnotic and antiparkinsonism drugs

This CodeT42.0X2SPoisoning by hydantoin derivatives, intentional self-harm, sequela

Present on Admission (POA)Billing

T42.0X2S 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).

Medicare Risk Adjustment (HCC)Billing

T42.0X2S no longer risk-adjusts for Medicare Advantage: it maps to no payment category in the live CMS-HCC V28 model, although it still risk-adjusts in the other CMS models shown below.

CMS-HCC V28 (Medicare Advantage Payment Model)

Not mapped

Dropped in V28 see all codes that no longer risk-adjust

Prior Model (CMS-HCC V24)

HCC 59

V24 retired last contributed to a Medicare Advantage risk score in payment year 2025

Other CMS Models

PACE (CMS-HCC V22): HCC 58 · ESRD (V21): HCC 58 · ESRD (V24): HCC 59

ESRD V21 weights: 0.091 dialysis, 0.217–0.260 functioning graft · ESRD V24 weights: 0.066 dialysis, 0.129–0.259 functioning graft

Part D (RxHCC)

Not mapped

T42.0X2S does not risk-adjust in the RxHCC prescription drug model

Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

Hydantoin derivative poisoning
Intentional phenytoin overdose
Intentional phenytoin poisoning
Phenytoin overdose
Poisoning by phenytoin

Coding GuidelinesGuidance

When coding a poisoning or reaction to the improper use of a medication (e.g., overdose, wrong substance given or taken in error, wrong route of administration), first assign the appropriate code from categories T36-T50. The poisoning codes have an associated intent as their 5th or 6th character (accidental, intentional self-harm, assault and undetermined). If the intent of the poisoning is unknown or unspecified, code the intent as accidental intent. The undetermined intent is only for use if the documentation in the record specifies that the intent cannot be determined. Use additional code(s) for all manifestations of poisonings.

The appropriate 7th character is to be added to each code from block Poisoning by, adverse effect of and underdosing of antiepileptic, sedative- hypnotic and antiparkinsonism drugs (T42). 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 T42.0X2S: its own notes plus those printed at T42, block T36-T50, and Chapter 19. A note printed at a category, block or chapter applies to every code under it.