2026 ICD-10-CM Diagnosis Code T44.2X4APoisoning by ganglionic blocking drugs, undetermined, initial encounter

ICD-10-CM Codes›S00–T88›T36-T50›T44

ICD-10-CM T44.2X4A
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

T44.2X4A is a billable ICD-10-CM diagnosis code for poisoning by ganglionic blocking drugs, 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
T44.2X4A
Billable Status
Yes — Valid for Submission
Code Describes
Poisoning by ganglionic blocking drugs, undetermined, initial encounter
Short Description
Poisoning by ganglionic blocking drugs, undetermined, init
Parent Code
T44.2X4
Poisoning by ganglionic blocking drugs, 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 CodeT44.2X4APoisoning by ganglionic blocking drugs, 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

  • Mecamylamine

    a nicotinic antagonist that is well absorbed from the gastrointestinal tract and crosses the blood-brain barrier. mecamylamine has been used as a ganglionic blocker in treating hypertension, but, like most ganglionic blockers, is more often used now as a research tool.

  • Pempidine

    a nicotinic antagonist most commonly used as an experimental tool. it has been used as a ganglionic blocker in the treatment of hypertension but has largely been supplanted for that purpose by more specific drugs.

  • Trimethaphan

    a nicotinic antagonist that has been used as a ganglionic blocker in hypertension, as an adjunct to anesthesia, and to induce hypotension during surgery.

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
Ganglionic blocking drug NECT44.2X1T44.2X2T44.2X3T44.2X4T44.2X5T44.2X6
Ganglionic blocking drug NEC::specified NECT44.2X1T44.2X2T44.2X3T44.2X4T44.2X5T44.2X6
Hexamethonium bromideT44.2X1T44.2X2T44.2X3T44.2X4T44.2X5T44.2X6
MecamylamineT44.2X1T44.2X2T44.2X3T44.2X4T44.2X5T44.2X6
PempidineT44.2X1T44.2X2T44.2X3T44.2X4T44.2X5T44.2X6
Pentamethonium bromideT44.2X1T44.2X2T44.2X3T44.2X4T44.2X5T44.2X6
Pentapyrrolinium (bitartrate)T44.2X1T44.2X2T44.2X3T44.2X4T44.2X5T44.2X6
Pentolonium tartrateT44.2X1T44.2X2T44.2X3T44.2X4T44.2X5T44.2X6
Tetraethylammonium chlorideT44.2X1T44.2X2T44.2X3T44.2X4T44.2X5T44.2X6
Tetrylammonium chlorideT44.2X1T44.2X2T44.2X3T44.2X4T44.2X5T44.2X6
Trimetaphan camsilateT44.2X1T44.2X2T44.2X3T44.2X4T44.2X5T44.2X6
TrimethaphanT44.2X1T44.2X2T44.2X3T44.2X4T44.2X5T44.2X6
TrimethidiniumT44.2X1T44.2X2T44.2X3T44.2X4T44.2X5T44.2X6

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 T44.2X4A to ICD-9-CMHistory

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

ICD-9-CM
972.3 Pois-ganglion block agt
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 T44.2X4AOverview

Is T44.2X4A (Poisoning by ganglionic blocking drugs, undetermined) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report poisoning by ganglionic blocking drugs, undetermined, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What does the 7th character A in T44.2X4A mean?

The final character A marks the initial encounter: use it while the patient is receiving active treatment for poisoning by ganglionic blocking drugs, undetermined, such as an emergency visit or first evaluation.

What MS-DRG does T44.2X4A group to?

When poisoning by ganglionic blocking drugs, 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 T44.2X4A?

Under the General Equivalence Mappings, poisoning by ganglionic blocking drugs, undetermined, initial encounter converts to ICD-9-CM 972.3 (pois-ganglion block agt) 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.