2027 ICD-10-CM Diagnosis Code T42.6X2SPoisoning by other antiepileptic and sedative-hypnotic drugs, intentional self-harm, sequela
T42.6X2S is a billable ICD-10-CM diagnosis code for poisoning by other antiepileptic and sedative-hypnotic drugs, 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. 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.
T42.6X2S 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
Code Classification
Present on Admission (POA)Billing
T42.6X2S 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
T42.6X2S 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.
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.
- Beclamide overdose
- Beclamide poisoning
- Chloral and/or chloral derivative overdose
- Chloral hydrate overdose
- Chlormethiazole overdose
- Chlormethiazole poisoning
- Chlormezanone overdose
- Chlormezanone poisoning
- Dichloralphenazone overdose
- Dichloralphenazone poisoning
- Gabapentin overdose
- Gabapentin poisoning
- Intentional barbiturate overdose
- Intentional beclamide overdose
- Intentional beclamide poisoning
- Intentional chloral hydrate overdose
- Intentional chloral hydrate poisoning
- Intentional chlormethiazole overdose
- Intentional chlormethiazole poisoning
- Intentional chlormezanone overdose
- Intentional chlormezanone poisoning
- Intentional dichloralphenazone overdose
- Intentional dichloralphenazone poisoning
- Intentional gabapentin overdose
- Intentional gabapentin poisoning
- Intentional lamotrigine overdose
- Intentional lamotrigine poisoning
- Intentional methyprylone overdose
- Intentional methyprylone poisoning
- Intentional overdose by calcium-channel blocker
- Intentional paraldehyde overdose
- Intentional paraldehyde poisoning
- Intentional piracetam overdose
- Intentional piracetam poisoning
- Intentional poisoning by calcium-channel blocker
- Intentional poisoning caused by valproate
- Intentional primidone overdose
- Intentional primidone poisoning
- Intentional triclofos overdose
- Intentional triclofos poisoning
- Intentional valproate overdose
- Intentional vigabatrin overdose
- Intentional vigabatrin poisoning
- Intentional zolpidem overdose
- Intentional zolpidem poisoning
- Intentional zopiclone overdose
- Intentional zopiclone poisoning
- Lamotrigine overdose
- Lamotrigine poisoning
- Methyprylone overdose
- Methyprylone poisoning
- Overdose of calcium-channel blockers
- Paraldehyde overdose
- Piracetam overdose
- Piracetam poisoning
- Poisoning by chloral hydrate
- Poisoning by paraldehyde
- Poisoning by primidone
- Poisoning caused by valproate
- Primidone overdose
- Triclofos overdose
- Triclofos poisoning
- Valproate overdose
- Vigabatrin overdose
- Vigabatrin poisoning
- Zolpidem overdose
- Zolpidem poisoning
- Zopiclone overdose
- Zopiclone poisoning
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 T42.6X2S: its own notes plus those printed at T42.6, T42, 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.
- poisoning by, adverse effect of and underdosing of carbamazepine (T42.1-)
- 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 T42
- 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 T42.6X2S, its category, or a range that includes it.
Excludes2 2
These codes carry an Excludes2 note naming T42.6X2S: its condition is not part of those codes, and both may be reported when the patient has both.
- F13.2 Sedative, hypnotic or anxiolytic-related dependencesedative, hypnotic, or anxiolytic poisoning (T42.-) names T42.-, which includes this code
- T43 Poisoning by, adverse effect of and underdosing of psychotropic drugs, not elsewhere classifiedmethaqualone (T42.6-) names T42.6-, 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
Poisoning
A poison is any substance that is harmful to your body. You might swallow it, inhale it, inject it, or absorb it through your skin. Any substance can be poisonous if too much is taken. Poisons can include:
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert T42.6X2S to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About T42.6X2SOverview
Is T42.6X2S a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report poisoning by other antiepileptic and sedative-hypnotic drugs, intentional self-harm, sequela on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What does the 7th character S in T42.6X2S mean?
The final character S makes this a sequela code: it reports a lingering problem that remains after the poisoning by other antiepileptic and sedative-hypnotic drugs, intentional self-harm itself has resolved, not the original event.
What MS-DRG does T42.6X2S group to?
When poisoning by other antiepileptic and sedative-hypnotic drugs, intentional self-harm, sequela is the principal diagnosis on an inpatient stay, it groups to MS-DRG 923, 922, with relative weights from 0.9980 to 1.6248 depending on complications. Higher weights mean higher Medicare reimbursement.
Is T42.6X2S 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 poisoning by other antiepileptic and sedative-hypnotic drugs, intentional self-harm, 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.
Can T42.6X2S be reported with a code from T42.1?
Not as a rule. The Excludes1 note at T42.6, which applies to T42.6X2S, lists "poisoning by, adverse effect of and underdosing of carbamazepine (T42.1-)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
Does T42.6X2S risk-adjust for Medicare Advantage payment?
Not for Medicare Advantage. T42.6X2S mapped to HCC 59 in the retired CMS-HCC V24 model, which last determined payment in 2025, but it maps to no category in the live V28 model; see all codes that no longer risk-adjust. It still risk-adjusts in the PACE (CMS-HCC V22) category 58 (Major Depressive/Bipolar/and Paranoid Disorders), ESRD (V21) category 58 (Major Depressive/Bipolar/and Paranoid Disorders), and ESRD (V24) category 59 (Major Depressive/Bipolar/and Paranoid Disorders).
