2026 ICD-10-CM Diagnosis Code T42.4X4APoisoning by benzodiazepines, undetermined, initial encounter
T42.4X4A is a billable ICD-10-CM diagnosis code for poisoning by benzodiazepines, undetermined, 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 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 917 through 918. Coders also document this condition as benzodiazepine overdose. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under External cause codes: intent of injury, undetermined; External cause codes: poisoning by drug; and Poisoning by drugs, initial encounter.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Benzodiazepine overdose
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.
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.
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 T42.4X4A to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About T42.4X4AOverview
Is T42.4X4A (Poisoning by benzodiazepines, undetermined) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report poisoning by benzodiazepines, undetermined, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character A in T42.4X4A mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for poisoning by benzodiazepines, undetermined, such as an emergency visit or first evaluation.
What MS-DRG does T42.4X4A group to?
When poisoning by benzodiazepines, undetermined, initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 917, 918, with relative weights from 0.8571 to 1.5684 depending on complications. Higher weights mean higher Medicare reimbursement.
What is the ICD-9 equivalent of T42.4X4A?
Under the General Equivalence Mappings, poisoning by benzodiazepines, undetermined, initial encounter converts to ICD-9-CM 969.4 (pois-benzodiazepine tran) and E980.2 (undet pois-sed/hypn NEC). 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.
