2026 ICD-10-CM Diagnosis Code T44.994APoisoning by other drug primarily affecting the autonomic nervous system, undetermined, initial encounter

ICD-10-CM Codes›S00–T88›T36-T50›T44

ICD-10-CM T44.994A
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

T44.994A is a billable ICD-10-CM diagnosis code for poisoning by other drug primarily affecting the autonomic nervous system, 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. 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

ICD-10-CM Code
T44.994A
Billable Status
Yes — Valid for Submission
Code Describes
Poisoning by other drug primarily affecting the autonomic nervous system, undetermined, initial encounter
Short Description
Poisn by oth drug aff the autonm nervous sys, undet, init
Parent Code
T44.994
Poisoning by other drug primarily affecting the autonomic nervous system, undetermined

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
CategoryT44Poisoning by, adverse effect of and underdosing of drugs primarily affecting the autonomic nervous system
This CodeT44.994APoisoning by other drug primarily affecting the autonomic nervous system, undetermined, initial encounter

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 drugs primarily affecting the autonomic nervous system (T44). 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 EXT023
External cause codes: intent of injury, undetermined
Default principal diagnosis: inpatient No · outpatient No
CCSR EXT014
External cause codes: poisoning by drug
Default principal diagnosis: inpatient No · outpatient No
CCSR INJ022
Poisoning by drugs, initial encounter
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Arylsulfotransferase

    a sulfotransferase that catalyzes the sulfation of a phenol in the presence of 3'-phosphoadenylylsulfate as sulfate donor to yield an aryl sulfate and adenosine 3',5'-bisphosphate. a number of aromatic compounds can act as acceptors; however, organic hydroxylamines are not substrates. sulfate conjugation by this enzyme is a major pathway for the biotransformation of phenolic and catechol drugs as well as neurotransmitters. ec 2.8.2.1.

  • Dopamine

    one of the catecholamine neurotransmitters in the brain. it is derived from tyrosine and is the precursor to norepinephrine and epinephrine. dopamine is a major transmitter in the extrapyramidal system of the brain, and important in regulating movement. a family of receptors (receptors, dopamine) mediate its action.

  • Dopamine Agents

    any drugs that are used for their effects on dopamine receptors, on the life cycle of dopamine, or on the survival of dopaminergic neurons.

  • Dopamine Agonists

    drugs that bind to and activate dopamine receptors.

  • Dopamine and cAMP-Regulated Phosphoprotein 32

    a phosphoprotein that was initially identified as a major target of dopamine activated adenylyl cyclase in the corpus striatum. it regulates the activities of protein phosphatase-1 and protein kinase a, and it is a key mediator of the biochemical, electrophysiological, transcriptional, and behavioral effects of dopamine.

  • Dopamine Antagonists

    drugs that bind to but do not activate dopamine receptors, thereby blocking the actions of dopamine or exogenous agonists. many drugs used in the treatment of psychotic disorders (antipsychotic agents) are dopamine antagonists, although their therapeutic effects may be due to long-term adjustments of the brain rather than to the acute effects of blocking dopamine receptors. dopamine antagonists have been used for several other clinical purposes including as antiemetics, in the treatment of tourette syndrome, and for hiccup. dopamine receptor blockade is associated with neuroleptic malignant syndrome.

  • Dopamine beta-Hydroxylase

    one of the catecholamine neurotransmitters in the brain. it is derived from tyrosine and is the precursor to norepinephrine and epinephrine. dopamine is a major transmitter in the extrapyramidal system of the brain, and important in regulating movement. a family of receptors (receptors, dopamine) mediate its action.

  • Dopamine D2 Receptor Antagonists

    compounds and drugs that bind to and inhibit or block the activation of dopamine d2 receptors.

  • Dopamine Plasma Membrane Transport Proteins

    sodium chloride-dependent neurotransmitter symporters located primarily on the plasma membrane of dopaminergic neurons. they remove dopamine from the extracellular space by high affinity reuptake into presynaptic terminals and are the target of dopamine uptake inhibitors.

  • Dopamine Uptake Inhibitors

    drugs that block the transport of dopamine into axon terminals or into storage vesicles within terminals. most of the adrenergic uptake inhibitors also inhibit dopamine uptake.

  • Dopaminergic Imaging

    functional brain imaging techniques that utilize various radionuclide tracers that bind to different targets in the synapses of dopaminergic neurons.

  • Dopaminergic Neurons

    neurons whose primary neurotransmitter is dopamine.

  • Receptors, Dopamine

    cell-surface proteins that bind dopamine with high affinity and trigger intracellular changes influencing the behavior of cells.

  • Receptors, Dopamine D1

    a subfamily of g-protein-coupled receptors that bind the neurotransmitter dopamine and modulate its effects. d1-class receptor genes lack introns, and the receptors stimulate adenylyl cyclases.

  • Receptors, Dopamine D2

    a subfamily of g-protein-coupled receptors that bind the neurotransmitter dopamine and modulate its effects. d2-class receptor genes contain introns, and the receptors inhibit adenylyl cyclases.

  • Receptors, Dopamine D3

    a subtype of dopamine d2 receptors that are highly expressed in the limbic system of the brain.

  • Receptors, Dopamine D4

    a subtype of dopamine d2 receptors that has high affinity for the antipsychotic clozapine.

  • Receptors, Dopamine D5

    a subtype of dopamine d1 receptors that has higher affinity for dopamine and differentially couples to gtp-binding proteins.

  • Ephedra

    a plant genus of the family ephedraceae, order ephedrales, class gnetopsida, division gnetophyta.

  • Ephedra sinica

    a plant species of the family ephedraceae, order ephedrales, class gnetopsida, division gnetophyta. it is a source of ephedrine and other alkaloids.

  • Ephedrine

    a phenethylamine found in ephedra sinica. pseudoephedrine is an isomer. it is an alpha- and beta-adrenergic agonist that may also enhance release of norepinephrine. it has been used for asthma, heart failure, rhinitis, and urinary incontinence, and for its central nervous system stimulatory effects in the treatment of narcolepsy and depression. it has become less extensively used with the advent of more selective agonists.

  • Pseudoephedrine

    a phenethylamine that is an isomer of ephedrine which has less central nervous system effects and usage is mainly for respiratory tract decongestion.

  • Mephentermine

    a sympathomimetic agent with specificity for alpha-1 adrenergic receptors. it is used to maintain blood pressure in hypotensive states such as following spinal anesthesia.

  • Phenylpropanolamine

    a sympathomimetic that acts mainly by causing release of norepinephrine but also has direct agonist activity at some adrenergic receptors. it is most commonly used as a nasal vasoconstrictor and an appetite depressant.

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
Amezinium metilsulfateT44.991T44.992T44.993T44.994T44.995T44.996
AngiotensinamideT44.991T44.992T44.993T44.994T44.995T44.996
BenzedrexT44.991T44.992T44.993T44.994T44.995T44.996
DopamineT44.991T44.992T44.993T44.994T44.995T44.996
EphedraT44.991T44.992T44.993T44.994T44.995T44.996
EphedrineT44.991T44.992T44.993T44.994T44.995T44.996
IbopamineT44.991T44.992T44.993T44.994T44.995T44.996
IsoephedrineT44.991T44.992T44.993T44.994T44.995T44.996
MephentermineT44.991T44.992T44.993T44.994T44.995T44.996
PhenylpropanolamineT44.991T44.992T44.993T44.994T44.995T44.996
PseudoephedrineT44.991T44.992T44.993T44.994T44.995T44.996

Convert T44.994A to ICD-9-CMHistory

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

ICD-9-CM
971.9 Pois-autonomic agent NOS
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
E980.4 Undet pois-med agnt NEC
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 T44.994AOverview

Is T44.994A a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report poisoning by other drug primarily affecting the autonomic nervous system, undetermined, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What does the 7th character A in T44.994A mean?

The final character A marks the initial encounter: use it while the patient is receiving active treatment for poisoning by other drug primarily affecting the autonomic nervous system, undetermined, such as an emergency visit or first evaluation.

What MS-DRG does T44.994A group to?

When poisoning by other drug primarily affecting the autonomic nervous system, 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 T44.994A?

Under the General Equivalence Mappings, poisoning by other drug primarily affecting the autonomic nervous system, undetermined, initial encounter converts to ICD-9-CM 971.9 (pois-autonomic agent NOS) and E980.4 (undet pois-med agnt 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.