2026 ICD-10-CM Diagnosis Code T49.95XAAdverse effect of unspecified topical agent, initial encounter

ICD-10-CM Codes›S00–T88›T36-T50›T49

ICD-10-CM T49.95XA
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

T49.95XA is a billable ICD-10-CM diagnosis code for adverse effect of unspecified topical agent, 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. 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
T49.95XA
Billable Status
Yes — Valid for Submission
Code Describes
Adverse effect of unspecified topical agent, initial encounter
Short Description
Adverse effect of unspecified topical agent, init encntr
Parent Code
T49.95
Adverse effect of unspecified topical agent

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
CategoryT49Poisoning by, adverse effect of and underdosing of topical agents primarily affecting skin and mucous membrane and by ophthalmological, otorhinorlaryngological and dental drugs
This CodeT49.95XAAdverse effect of unspecified topical agent, initial encounter

Code EditsBilling

Medicare Code Editor checks that affect claim validity for T49.95XA.

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.

  • Acute phototoxic reaction
  • Drug pigmentation
  • Drug-induced pigmentation
  • Dusting powders adverse reaction
  • Non-melanin pigmentation caused by drug
  • Non-melanin pigmentation caused by exogenous substance
  • Phototoxic reaction to topical chemical
  • Phototoxic reaction to topically applied medicament
  • Pigmentation due to topically applied medicament
  • Skin disorder monitoring status
  • Skin drug side effect
  • Topical agent 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 topical agents primarily affecting skin and mucous membrane and by ophthalmological, otorhinorlaryngological and dental drugs (T49). 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

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
External medications (skin) (mucous membrane)T49.91T49.92T49.93T49.94T49.95T49.96
External medications (skin) (mucous membrane)::dental agentT49.91T49.92T49.93T49.94T49.95T49.96
External medications (skin) (mucous membrane)::ENT agentT49.91T49.92T49.93T49.94T49.95T49.96
External medications (skin) (mucous membrane)::ophthalmic preparationT49.91T49.92T49.93T49.94T49.95T49.96
External medications (skin) (mucous membrane)::specified NECT49.91T49.92T49.93T49.94T49.95T49.96
Liniments NECT49.91T49.92T49.93T49.94T49.95T49.96
Lotions NECT49.91T49.92T49.93T49.94T49.95T49.96
Mucous membrane agents (external)T49.91T49.92T49.93T49.94T49.95T49.96
Mucous membrane agents (external)::specified NECT49.91T49.92T49.93T49.94T49.95T49.96
SkinT49.91T49.92T49.93T49.94T49.95T49.96
Skin::agents (external)T49.91T49.92T49.93T49.94T49.95T49.96
Skin::agents (external)::specified NECT49.91T49.92T49.93T49.94T49.95T49.96
Skin::test antigenT49.91T49.92T49.93T49.94T49.95T49.96
Topical action drug NECT49.91T49.92T49.93T49.94T49.95T49.96
Topical action drug NEC::ear, nose or throatT49.91T49.92T49.93T49.94T49.95T49.96
Topical action drug NEC::eyeT49.91T49.92T49.93T49.94T49.95T49.96
Topical action drug NEC::skinT49.91T49.92T49.93T49.94T49.95T49.96
Topical action drug NEC::specified NECT49.91T49.92T49.93T49.94T49.95T49.96

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 T49.95XA 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
E946.9 Adv eff skin agent 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 T49.95XAOverview

Is T49.95XA (Adverse effect of unspecified topical agent) a billable code?

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

What does the 7th character A in T49.95XA mean?

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

What MS-DRG does T49.95XA group to?

On inpatient claims, adverse effect of unspecified topical agent, 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 T49.95XA be a principal diagnosis?

No. The Medicare Code Editor rejects this code as a principal diagnosis because adverse effect of unspecified topical agent, 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 T49.95XA?

Under the General Equivalence Mappings, adverse effect of unspecified topical agent, initial encounter converts to ICD-9-CM 995.29 (adv eff med/biol NEC/NOS) and E946.9 (adv eff skin agent 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.