2026 ICD-10-CM Diagnosis Code T48.291APoisoning by other drugs acting on muscles, accidental (unintentional), initial encounter

ICD-10-CM Codes›S00–T88›T36-T50›T48

ICD-10-CM T48.291A
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

T48.291A is a billable ICD-10-CM diagnosis code for poisoning by other drugs acting on muscles, accidental (unintentional), 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 accidental metaproterenol poisoning. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under External cause codes: intent of injury, accidental/unintentional; External cause codes: poisoning by drug; and Poisoning by drugs, initial encounter.

Code Identity

ICD-10-CM Code
T48.291A
Billable Status
Yes — Valid for Submission
Code Describes
Poisoning by other drugs acting on muscles, accidental (unintentional), initial encounter
Short Description
Poisoning by oth drugs acting on muscles, accidental, init
Parent Code
T48.291
Poisoning by other drugs acting on muscles, accidental (unintentional)

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
CategoryT48Poisoning by, adverse effect of and underdosing of agents primarily acting on smooth and skeletal muscles and the respiratory system
This CodeT48.291APoisoning by other drugs acting on muscles, accidental (unintentional), initial encounter

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Accidental metaproterenol poisoning
  • Accidental poisoning by adrenergics
  • Poisoning by metaproterenol

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 agents primarily acting on smooth and skeletal muscles and the respiratory system (T48). 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 EXT020
External cause codes: intent of injury, accidental/unintentional
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

  • Metaproterenol

    a beta-2 adrenergic agonist used in the treatment of asthma and bronchial spasm.

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
BotoxT48.291T48.292T48.293T48.294T48.295T48.296
BruceineT48.291T48.292T48.293T48.294T48.295T48.296
DipropylineT48.291T48.292T48.293T48.294T48.295T48.296
HydrastineT48.291T48.292T48.293T48.294T48.295T48.296
LututrinT48.291T48.292T48.293T48.294T48.295T48.296
MetaproterenolT48.291T48.292T48.293T48.294T48.295T48.296
OrciprenalineT48.291T48.292T48.293T48.294T48.295T48.296

Patient EducationClinical

Medication Errors

Medicines treat infectious diseases, prevent problems from chronic diseases, and ease pain. But medicines can also cause harmful reactions if not used correctly. Errors can happen in the hospital, at the health care provider's office, at the pharmacy, or at home. You can help prevent errors by:

Read the full article at MedlinePlus

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

Convert T48.291A to ICD-9-CMHistory

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

ICD-9-CM
975.1 Pois-smooth muscle relax
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
E858.6 Acc poisn-muscl/resp 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
975.3 Poison-muscle agent NEC
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
E858.6 Acc poisn-muscl/resp agt
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 T48.291AOverview

Is T48.291A a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report poisoning by other drugs acting on muscles, accidental (unintentional), initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What does the 7th character A in T48.291A mean?

The final character A marks the initial encounter: use it while the patient is receiving active treatment for poisoning by other drugs acting on muscles, accidental (unintentional), such as an emergency visit or first evaluation.

What MS-DRG does T48.291A group to?

When poisoning by other drugs acting on muscles, accidental (unintentional), 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 T48.291A?

Under the General Equivalence Mappings, poisoning by other drugs acting on muscles, accidental (unintentional), initial encounter converts to ICD-9-CM 975.1 (pois-smooth muscle relax), E858.6 (acc poisn-muscl/resp agt), and 975.3 (poison-muscle agent 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.