2026 ICD-10-CM Diagnosis Code T42.4X1SPoisoning by benzodiazepines, accidental (unintentional), sequela

ICD-10-CM CodesS00–T88T36-T50T42

ICD-10-CM T42.4X1S
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

T42.4X1S is a billable ICD-10-CM diagnosis code for poisoning by benzodiazepines, accidental (unintentional), 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 2026 (October 1, 2025 through September 30, 2026) 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 Poisoning/toxic effect/adverse effects/underdosing, sequela.

Code Identity

ICD-10-CM Code
T42.4X1S
Billable Status
Yes — Valid for Submission
Code Describes
Poisoning by benzodiazepines, accidental (unintentional), sequela
Short Description
Poisoning by benzodiazepines, accidental, sequela
Parent Code
Poisoning by benzodiazepines, accidental (unintentional)

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 CodeT42.4X1SPoisoning by benzodiazepines, accidental (unintentional), sequela

Present on Admission (POA)Billing

T42.4X1S is exempt from POA reporting on inpatient claims to general acute care hospitals. Review other POA exempt codes.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Accidental alprazolam overdose
  • Accidental alprazolam poisoning
  • Accidental bromazepam overdose
  • Accidental bromazepam poisoning
  • Accidental chlordiazepoxide overdose
  • Accidental clobazam overdose
  • Accidental clobazam poisoning
  • Accidental clonazepam overdose
  • Accidental clonazepam poisoning
  • Accidental clorazepate overdose
  • Accidental clorazepate poisoning
  • Accidental clozapine overdose
  • Accidental clozapine poisoning
  • Accidental diazepam overdose
  • Accidental flunitrazepam overdose
  • Accidental flunitrazepam poisoning
  • Accidental flurazepam overdose
  • Accidental ketazolam overdose
  • Accidental ketazolam poisoning
  • Accidental loprazolam overdose
  • Accidental loprazolam poisoning
  • Accidental lorazepam overdose
  • Accidental lormetazepam overdose
  • Accidental lormetazepam poisoning
  • Accidental medazepam overdose
  • Accidental midazolam overdose
  • Accidental midazolam poisoning
  • Accidental nitrazepam overdose
  • Accidental overdose by temazepam
  • Accidental overdose of benzodiazepine
  • Accidental oxazepam overdose
  • Accidental oxazepam poisoning
  • Accidental poisoning by benzodiazepine-based tranquilizer
  • Accidental poisoning by chlordiazepoxide
  • Accidental poisoning by diazepam
  • Accidental poisoning by flurazepam
  • Accidental poisoning by lorazepam
  • Accidental poisoning by medazepam
  • Accidental poisoning by nitrazepam
  • Accidental poisoning by temazepam
  • Accidental prazepam overdose
  • Accidental prazepam poisoning
  • Accidental triazolam overdose
  • Accidental triazolam poisoning
  • Alprazolam overdose
  • Alprazolam poisoning
  • Bromazepam overdose
  • Bromazepam poisoning
  • Chlordiazepoxide overdose
  • Clobazam overdose
  • Clobazam poisoning
  • Clonazepam overdose
  • Clonazepam poisoning
  • Clorazepate overdose
  • Clorazepate poisoning
  • Clozapine overdose
  • Clozapine poisoning
  • Diazepam overdose
  • Flunitrazepam overdose
  • Flunitrazepam poisoning
  • Flurazepam overdose
  • Ketazolam overdose
  • Ketazolam poisoning
  • Loprazolam overdose
  • Loprazolam poisoning
  • Lorazepam overdose
  • Lormetazepam overdose
  • Lormetazepam poisoning
  • Medazepam overdose
  • Midazolam overdose
  • Midazolam poisoning
  • Nitrazepam overdose
  • Overdose of temazepam
  • Oxazepam overdose
  • Oxazepam poisoning
  • Poisoning by benzodiazepine-based tranquilizer
  • Poisoning by chlordiazepoxide
  • Poisoning by diazepam
  • Poisoning by flurazepam
  • Poisoning by lorazepam
  • Poisoning by medazepam
  • Poisoning by nitrazepam
  • Poisoning by temazepam
  • Prazepam overdose
  • Prazepam poisoning
  • Triazolam overdose
  • Triazolam 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 2026, published by CMS and the National Center for Health Statistics.

Clinical ClassificationClinical

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

CCSR INJ075
Poisoning/toxic effect/adverse effects/underdosing, sequela
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Alprazolam

    a triazolobenzodiazepine compound with antianxiety and sedative-hypnotic actions, that is efficacious in the treatment of panic disorders, with or without agoraphobia, and in generalized anxiety disorders. (from ama drug evaluations annual, 1994, p238)
  • Bromazepam

    one of the benzodiazepines that is used in the treatment of anxiety disorders.
  • Chlordiazepoxide

    an anxiolytic benzodiazepine derivative with anticonvulsant, sedative, and amnesic properties. it has also been used in the symptomatic treatment of alcohol withdrawal.
  • Clobazam

    a benzodiazepine derivative that is a long-acting gaba-a receptor agonist. it is used as an antiepileptic in the treatment of seizures, including seizures associated with lennox-gastaut syndrome. it is also used as an anxiolytic, for the short-term treatment of acute anxiety.
  • Clonazepam

    an anticonvulsant used for several types of seizures, including myotonic or atonic seizures, photosensitive epilepsy, and absence seizures, although tolerance may develop. it is seldom effective in generalized tonic-clonic or partial seizures. the mechanism of action appears to involve the enhancement of gamma-aminobutyric acid receptor responses.
  • Clozapine

    a tricylic dibenzodiazepine, classified as an atypical antipsychotic agent. it binds several types of central nervous system receptors, and displays a unique pharmacological profile. clozapine is a serotonin antagonist, with strong binding to 5-ht 2a/2c receptor subtype. it also displays strong affinity to several dopaminergic receptors, but shows only weak antagonism at the dopamine d2 receptor, a receptor commonly thought to modulate neuroleptic activity. agranulocytosis is a major adverse effect associated with administration of this agent.
  • Diazepam

    a benzodiazepine with anticonvulsant, anxiolytic, sedative, muscle relaxant, and amnesic properties and a long duration of action. its actions are mediated by enhancement of gamma-aminobutyric acid activity.
  • Diazepam Binding Inhibitor

    an 86-amino acid polypeptide, found in central and peripheral tissues, that displaces diazepam from the benzodiazepine recognition site on the gamma-aminobutyric acid receptor (receptors, gaba). it also binds medium- and long-chain acyl-coa esters and serves as an acyl-coa transporter. this peptide regulates lipid metabolism.
  • Receptors, GABA-A

    cell surface proteins which bind gamma-aminobutyric acid and contain an integral membrane chloride channel. each receptor is assembled as a pentamer from a pool of at least 19 different possible subunits. the receptors belong to a superfamily that share a common cysteine loop.
  • Estazolam

    a benzodiazepine with anticonvulsant, hypnotic, and muscle relaxant properties. it has been shown in some cases to be more potent than diazepam or nitrazepam.
  • Flunitrazepam

    a benzodiazepine with pharmacologic actions similar to those of diazepam that can cause anterograde amnesia. some reports indicate that it is used as a date rape drug and suggest that it may precipitate violent behavior. the united states government has banned the importation of this drug.
  • Flurazepam

    a benzodiazepine derivative used mainly as a hypnotic.
  • Lorazepam

    a benzodiazepine used as an anti-anxiety agent with few side effects. it also has hypnotic, anticonvulsant, and considerable sedative properties and has been proposed as a preanesthetic agent.
  • Medazepam

    a benzodiazepine derivative used in the treatment of anxiety. it has sedative, muscle relaxant, and anticonvulsant properties. one of its metabolites is diazepam and one of its excretion products is oxazepam.
  • Midazolam

    a short-acting hypnotic-sedative drug with anxiolytic and amnestic properties. it is used in dentistry, cardiac surgery, endoscopic procedures, as preanesthetic medication, and as an adjunct to local anesthesia. the short duration and cardiorespiratory stability makes it useful in poor-risk, elderly, and cardiac patients. it is water-soluble at ph less than 4 and lipid-soluble at physiological ph.
  • Nitrazepam

    a benzodiazepine derivative used as an anticonvulsant and hypnotic.
  • Nordazepam

    an intermediate in the metabolism of diazepam to oxazepam. it may have actions similar to those of diazepam.
  • Oxazepam

    a benzodiazepine used in the treatment of anxiety, alcohol withdrawal, and insomnia.
  • Prazepam

    a benzodiazepine that is used in the treatment of anxiety disorders.
  • Temazepam

    a benzodiazepine that acts as a gamma-aminobutyric acid modulator and anti-anxiety agent.
  • Triazolam

    a short-acting benzodiazepine used in the treatment of insomnia. some countries temporarily withdrew triazolam from the market because of concerns about adverse reactions, mostly psychological, associated with higher dose ranges. its use at lower doses with appropriate care and labeling has been reaffirmed by the fda and most other countries.

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
AlprazolamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
BentazepamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
BenzodiapinT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
Benzodiazepine NECT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
BromazepamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
BrotizolamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
CamazepamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
CarpipramineT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
ChlordiazepoxideT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
ClobazamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
ClonazepamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
Clorazepate (dipotassium)T42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
ClotiazepamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
CloxazolamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
ClozapineT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
DalmaneT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
DelorazepamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
DiazepamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
EstazolamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
EtizolamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
FludiazepamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
FlunitrazepamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
FlurazepamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
FlutazolamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
FlutoprazepamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
HalazepamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
HaloxazolamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
KetazolamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
LibriumT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
LoprazolamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
LorazepamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
LormetazepamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
MedazepamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
MexazolamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
MidazolamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
NimetazepamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
NitrazepamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
NordazepamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
OxazepamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
OxazolamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
PerlapineT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
PinazepamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
PrazepamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
QuazepamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
RohypnolT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
SeraxT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
TemazepamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
TetrazepamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
TofisopamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
TranxeneT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
TriazolamT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6
ValiumT42.4X1T42.4X2T42.4X3T42.4X4T42.4X5T42.4X6

Patient EducationClinical

Medication Errors

Medicines treat infectious diseases, prevent problems from chronic diseases, and ease pain. But medicines can also cause harmful reactions if not used correctly. Errors can happen in the hospital, at the health care provider's office, at the pharmacy, or at home. You can help prevent errors by:

Read the full article at MedlinePlus

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

Convert T42.4X1S to ICD-9-CMHistory

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

ICD-9-CM
909.0 Late eff drug poisoning
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
E929.2 Late eff acc poisoning
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 T42.4X1SOverview

Is T42.4X1S (Poisoning by benzodiazepines, accidental (unintentional)) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report poisoning by benzodiazepines, accidental (unintentional), sequela on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What does the 7th character S in T42.4X1S mean?

The final character S makes this a sequela code: it reports a lingering problem that remains after the poisoning by benzodiazepines, accidental (unintentional) itself has resolved, not the original event.

What MS-DRG does T42.4X1S group to?

When poisoning by benzodiazepines, accidental (unintentional), sequela is the principal diagnosis on an inpatient stay, it groups to MS-DRG 922, 923, with relative weights from 1.0177 to 1.7494 depending on complications. Higher weights mean higher Medicare reimbursement.

Is T42.4X1S 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 benzodiazepines, accidental (unintentional), sequela on inpatient claims.

What is the ICD-9 equivalent of T42.4X1S?

Under the General Equivalence Mappings, poisoning by benzodiazepines, accidental (unintentional), sequela converts to ICD-9-CM 909.0 (late eff drug poisoning) and E929.2 (late eff acc poisoning). 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.