2026 ICD-10-CM Diagnosis Code T37.95XAAdverse effect of unspecified systemic anti-infective and antiparasitic, initial encounter

ICD-10-CM Codes›S00–T88›T36-T50›T37

ICD-10-CM T37.95XA
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

T37.95XA is a billable ICD-10-CM diagnosis code for adverse effect of unspecified systemic anti-infective and antiparasitic, 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 allergic reaction caused by antiinfective agent. 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
T37.95XA
Billable Status
Yes — Valid for Submission
Code Describes
Adverse effect of unspecified systemic anti-infective and antiparasitic, initial encounter
Short Description
Advrs effect of unsp sys anti-infect and antiparasitic, init
Parent Code
T37.95
Adverse effect of unspecified systemic anti-infective and antiparasitic

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
CategoryT37Poisoning by, adverse effect of and underdosing of other systemic anti-infectives and antiparasitics
This CodeT37.95XAAdverse effect of unspecified systemic anti-infective and antiparasitic, initial encounter

Code EditsBilling

Medicare Code Editor checks that affect claim validity for T37.95XA.

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.

  • Allergic reaction caused by antiinfective agent
  • Antifungal drug adverse reaction
  • Anti-infectives adverse reaction
  • Contact dermatitis caused by scabicide
  • Fetal disorder caused by anti-infective agent transmitted via placenta

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 other systemic anti-infectives and antiparasitics (T37). 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

  • Acriflavine

    3,6-diamino-10-methylacridinium chloride mixt. with 3,6-acridinediamine. fluorescent dye used as a local antiseptic and also as a biological stain. it intercalates into nucleic acids thereby inhibiting bacterial and viral replication.

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
AcriflavineT37.91T37.92T37.93T37.94T37.95T37.96
Anti-infective NECT37.91T37.92T37.93T37.94T37.95T37.96
Anti-infective NEC::anthelminticT37.91T37.92T37.93T37.94T37.95T37.96
Anti-infective NEC::antibioticsT37.91T37.92T37.93T37.94T37.95T37.96
Anti-infective NEC::antibiotics::specified NECT37.91T37.92T37.93T37.94T37.95T37.96
Anti-infective NEC::antimalarialT37.91T37.92T37.93T37.94T37.95T37.96
Anti-infective NEC::antimycobacterial NECT37.91T37.92T37.93T37.94T37.95T37.96
Anti-infective NEC::antimycobacterial NEC::antibioticsT37.91T37.92T37.93T37.94T37.95T37.96
Anti-infective NEC::antiprotozoal NECT37.91T37.92T37.93T37.94T37.95T37.96
Anti-infective NEC::antiprotozoal NEC::bloodT37.91T37.92T37.93T37.94T37.95T37.96
Anti-infective NEC::antiviralT37.91T37.92T37.93T37.94T37.95T37.96
Anti-infective NEC::arsenicalT37.91T37.92T37.93T37.94T37.95T37.96
Anti-infective NEC::bismuth, localT37.91T37.92T37.93T37.94T37.95T37.96
Anti-infective NEC::ENTT37.91T37.92T37.93T37.94T37.95T37.96
Anti-infective NEC::eye NECT37.91T37.92T37.93T37.94T37.95T37.96
Anti-infective NEC::heavy metals NECT37.91T37.92T37.93T37.94T37.95T37.96
Anti-infective NEC::local NECT37.91T37.92T37.93T37.94T37.95T37.96
Anti-infective NEC::local NEC::specified NECT37.91T37.92T37.93T37.94T37.95T37.96
Anti-infective NEC::mixedT37.91T37.92T37.93T37.94T37.95T37.96
Anti-infective NEC::ophthalmic preparationT37.91T37.92T37.93T37.94T37.95T37.96
Anti-infective NEC::topical NECT37.91T37.92T37.93T37.94T37.95T37.96
Antiparasitic drug (systemic)T37.91T37.92T37.93T37.94T37.95T37.96
Antiparasitic drug (systemic)::localT37.91T37.92T37.93T37.94T37.95T37.96
Antiparasitic drug (systemic)::specified NECT37.91T37.92T37.93T37.94T37.95T37.96
EthoxazeneT37.91T37.92T37.93T37.94T37.95T37.96
FuradantinT37.91T37.92T37.93T37.94T37.95T37.96
FuroxoneT37.91T37.92T37.93T37.94T37.95T37.96
NifuraldezoneT37.91T37.92T37.93T37.94T37.95T37.96
Serenium (hydrochloride)T37.91T37.92T37.93T37.94T37.95T37.96

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 T37.95XA 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
E931.9 Adv eff antinfct 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 T37.95XAOverview

Is T37.95XA a billable code?

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

What does the 7th character A in T37.95XA mean?

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

What MS-DRG does T37.95XA group to?

On inpatient claims, adverse effect of unspecified systemic anti-infective and antiparasitic, 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 T37.95XA be a principal diagnosis?

No. The Medicare Code Editor rejects this code as a principal diagnosis because adverse effect of unspecified systemic anti-infective and antiparasitic, 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 T37.95XA?

Under the General Equivalence Mappings, adverse effect of unspecified systemic anti-infective and antiparasitic, initial encounter converts to ICD-9-CM 995.29 (adv eff med/biol NEC/NOS) and E931.9 (adv eff antinfct NEC/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.