2026 ICD-10-CM Diagnosis Code T48.905SAdverse effect of unspecified agents primarily acting on the respiratory system, sequela

ICD-10-CM Codes›S00–T88›T36-T50›T48

ICD-10-CM T48.905S
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

T48.905S is a billable ICD-10-CM diagnosis code for adverse effect of unspecified agents primarily acting on the respiratory system, 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 not accepted as a principal diagnosis by the Medicare Code Editor and exempt from POA reporting. Coders also document this condition as respiratory drug side effect. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Poisoning/toxic effect/adverse effects/underdosing, sequela.

Code Identity

ICD-10-CM Code
T48.905S
Billable Status
Yes — Valid for Submission
Code Describes
Adverse effect of unspecified agents primarily acting on the respiratory system, sequela
Short Description
Advrs effect of unsp agents prim act on the resp sys, sqla
Parent Code
T48.905
Adverse effect of unspecified agents primarily acting on the respiratory system

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 CodeT48.905SAdverse effect of unspecified agents primarily acting on the respiratory system, sequela

Code EditsBilling

Medicare Code Editor checks that affect claim validity for T48.905S.

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.

Present on Admission (POA)Billing

T48.905S is exempt from POA reporting on inpatient claims to general acute care hospitals. Review other POA exempt codes.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Respiratory drug side effect
  • Respiratory stimulant 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 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 INJ075
Poisoning/toxic effect/adverse effects/underdosing, sequela
Default principal diagnosis: inpatient No · outpatient Yes

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
Respiratory drug NECT48.901T48.902T48.903T48.904T48.905T48.906
Respiratory drug NEC::antiasthmatic NECT48.901T48.902T48.903T48.904T48.905T48.906
Respiratory drug NEC::anti-common-cold NECT48.901T48.902T48.903T48.904T48.905T48.906
Respiratory drug NEC::expectorant NECT48.901T48.902T48.903T48.904T48.905T48.906
Respiratory drug NEC::stimulantT48.901T48.902T48.903T48.904T48.905T48.906

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 T48.905S to ICD-9-CMHistory

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

ICD-9-CM
909.5 Lte efct advrs efct drug
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
E945.8 Adv eff resp drg NEC/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 T48.905SOverview

Is T48.905S a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report adverse effect of unspecified agents primarily acting on the respiratory system, sequela on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What does the 7th character S in T48.905S mean?

The final character S makes this a sequela code: it reports a lingering problem that remains after the adverse effect of unspecified agents primarily acting on the respiratory system itself has resolved, not the original event.

What MS-DRG does T48.905S group to?

On inpatient claims, adverse effect of unspecified agents primarily acting on the respiratory system, sequela maps to MS-DRG 922, 923, with relative weights from 1.0177 to 1.7494 depending on complications. Higher weights mean higher Medicare reimbursement.

Can T48.905S be a principal diagnosis?

No. The Medicare Code Editor rejects this code as a principal diagnosis because adverse effect of unspecified agents primarily acting on the respiratory system, sequela describes a circumstance that influences health status rather than a current illness. Report it as a secondary diagnosis.

Is T48.905S 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 adverse effect of unspecified agents primarily acting on the respiratory system, sequela on inpatient claims.

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.