2026 ICD-10-CM Diagnosis Code T42.6X3SPoisoning by other antiepileptic and sedative-hypnotic drugs, assault, sequela
T42.6X3S is a billable ICD-10-CM diagnosis code for poisoning by other antiepileptic and sedative-hypnotic drugs, assault, 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 Mental and substance use disorders; sequela; and Poisoning/toxic effect/adverse effects/underdosing, sequela.
Code Identity
Code Classification
Present on Admission (POA)Billing
T42.6X3S is exempt from POA reporting on inpatient claims to general acute care hospitals. Review other POA exempt codes.
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
Bromine
a halogen with the atomic symbol br, atomic number 35, and atomic weight 79.904. it is a volatile reddish-brown liquid that gives off suffocating vapors, is corrosive to the skin, and may cause severe gastroenteritis if ingested.Bromine Compounds
inorganic compounds that contain bromine as an integral part of the molecule.Bromine Radioisotopes
unstable isotopes of bromine that decay or disintegrate emitting radiation. br atoms with atomic weights 74-78, 80, and 82-90 are radioactive bromine isotopes.Bromisovalum
a sedative and mild hypnotic with potentially toxic effects.Chlormethiazole
a sedative and anticonvulsant often used in the treatment of alcohol withdrawal. chlormethiazole has also been proposed as a neuroprotective agent. the mechanism of its therapeutic activity is not entirely clear, but it does potentiate gamma-aminobutyric acid receptors response and it may also affect glycine receptors.Chlormezanone
a non-benzodiazepine that is used in the management of anxiety. it has been suggested for use in the treatment of muscle spasm.Ethchlorvynol
a sedative and hypnotic that has been used in the short-term management of insomnia. its use has been superseded by other drugs.Glutethimide
a hypnotic and sedative. its use has been largely superseded by other drugs.Paraldehyde
a hypnotic and sedative with anticonvulsant effects. however, because of the hazards associated with its administration, its tendency to react with plastic, and the risks associated with its deterioration, it has largely been superseded by other agents. it is still occasionally used to control status epilepticus resistant to conventional treatment. (from martindale, the extra pharmacopoeia, 30th ed, p608-9)Primidone
a barbiturate derivative that acts as a gaba modulator and anti-epileptic agent. it is partly metabolized to phenobarbital in the body and owes some of its actions to this metabolite.Dipsacales
an order of dicotyledonous flowering plants which includes six families. it is best known for its ornamental plants such as lonicera (honeysuckle), viburnum (arrowwood and guelder rose), and scabiosa (scabious, or pincushion flower).Valerian
a plant genus of the family valerianaceae, order dipsacales, subclass asteridae, class magnoliopsida. it is best known for the sedative use and valepotriate content of the roots. it is sometimes called garden heliotrope but is unrelated to true heliotrope (heliotropium).Valerianaceae
the valerian plant family of the order dipsacales, subclass asteridae, class magnoliopsida that is characterized by 3-5-lobed tubular flowers, often spurred at the base and clustered in tight heads.Valerianella
a plant genus of the family valerianaceae. it is sometimes called goosefoot cornsalad but should not be confused with true goosefoot (chenopodium).Valproic Acid
a fatty acid with anticonvulsant and anti-manic properties that is used in the treatment of epilepsy and bipolar disorder. the mechanisms of its therapeutic actions are not well understood. it may act by increasing gamma-aminobutyric acid levels in the brain or by altering the properties of voltage-gated sodium channels.Vigabatrin
an analogue of gamma-aminobutyric acid. it is an irreversible inhibitor of 4-aminobutyrate transaminase, the enzyme responsible for the catabolism of gamma-aminobutyric acid and is used as an anticonvulsant. (from martindale the extra pharmacopoeia, 31st ed)Zolpidem
an imidazopyridine derivative and short-acting gaba-a receptor agonist that is used for the treatment of insomnia.
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 T42.6X3S to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About T42.6X3SOverview
Is T42.6X3S a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report poisoning by other antiepileptic and sedative-hypnotic drugs, assault, sequela on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character S in T42.6X3S 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, assault itself has resolved, not the original event.
What MS-DRG does T42.6X3S group to?
When poisoning by other antiepileptic and sedative-hypnotic drugs, assault, 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 T42.6X3S 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, assault, sequela on inpatient claims.
What is the ICD-9 equivalent of T42.6X3S?
Under the General Equivalence Mappings, poisoning by other antiepileptic and sedative-hypnotic drugs, assault, sequela converts to ICD-9-CM 909.0 (late eff drug poisoning) and E969 (late effect assault). 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.
