2026 ICD-10-CM Diagnosis Code T44.2X5AAdverse effect of ganglionic blocking drugs, initial encounter

ICD-10-CM Codes›S00–T88›T36-T50›T44

ICD-10-CM T44.2X5A
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

T44.2X5A is a billable ICD-10-CM diagnosis code for adverse effect of ganglionic blocking drugs, 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. The code is not accepted as a principal diagnosis by the Medicare Code Editor. Coders also document this condition as adverse reaction to ganglion blocking drug. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Adverse effects of drugs and medicaments, initial encounter.

Code Identity

ICD-10-CM Code
T44.2X5A
Billable Status
Yes — Valid for Submission
Code Describes
Adverse effect of ganglionic blocking drugs, initial encounter
Short Description
Adverse effect of ganglionic blocking drugs, init encntr
Parent Code
T44.2X5
Adverse effect of ganglionic blocking drugs

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 CodeT44.2X5AAdverse effect of ganglionic blocking drugs, initial encounter

Code EditsBilling

Medicare Code Editor checks that affect claim validity for T44.2X5A.

Unacceptable principal diagnosis
There are selected codes that describe a circumstance which influences an individual's health status but not a current illness or injury, or codes that are not specific manifestations but may be due to an underlying cause. These codes are considered unacceptable as a principal diagnosis.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Adverse reaction to ganglion blocking drug
  • Adverse reaction to pentamethonium bromide
  • Trimetaphan adverse reaction

Coding GuidelinesGuidance

When coding an adverse effect of a drug that has been correctly prescribed and properly administered, assign the appropriate code for the nature of the adverse effect followed by the appropriate code for the adverse effect of the drug.

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 INJ028
Adverse effects of drugs and medicaments, initial encounter
Default principal diagnosis: inpatient No · 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

Drug Reactions

Most of the time, medicines make our lives better. They reduce aches and pains, fight infections, and control problems such as high blood pressure or diabetes. But medicines can also cause unwanted reactions, such as drug interactions, side effects, and allergies.

The full article covers:

  • What is a drug interaction?
  • What are side effects?
  • What are drug allergies?
  • How can I stay safe when taking medicines?

Read the full article at MedlinePlus

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

Convert T44.2X5A to ICD-9-CMHistory

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

ICD-9-CM
995.29 Adv eff med/biol NEC/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
E941.9 Adv eff autonom agnt NOS
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 T44.2X5AOverview

Is T44.2X5A (Adverse effect of ganglionic blocking drugs) a billable code?

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

What does the 7th character A in T44.2X5A mean?

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

What MS-DRG does T44.2X5A group to?

On inpatient claims, adverse effect of ganglionic blocking drugs, initial encounter maps to MS-DRG 917, 918, with relative weights from 0.8571 to 1.5684 depending on complications. Higher weights mean higher Medicare reimbursement.

Can T44.2X5A be a principal diagnosis?

No. The Medicare Code Editor rejects this code as a principal diagnosis because adverse effect of ganglionic blocking drugs, initial encounter describes a circumstance that influences health status rather than a current illness. Report it as a secondary diagnosis.

What is the ICD-9 equivalent of T44.2X5A?

Under the General Equivalence Mappings, adverse effect of ganglionic blocking drugs, initial encounter converts to ICD-9-CM 995.29 (adv eff med/biol NEC/NOS) and E941.9 (adv eff autonom agnt NOS). 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.