2026 ICD-10-CM Diagnosis Code Z16.33Resistance to antiviral drug(s)

ICD-10-CM Codes›Z00–Z99›Z16›Z16

ICD-10-CM Z16.33
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

Z16.33 is a billable ICD-10-CM diagnosis code for resistance to antiviral drug(s). It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 867 through 869. The code is not accepted as a principal diagnosis by the Medicare Code Editor. Coders also document this condition as amantadine resistant virus present. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Resistance to antimicrobial drugs.

Code Identity

ICD-10-CM Code
Z16.33
Billable Status
Yes — Valid for Submission
Code Describes
Resistance to antiviral drug(s)
Short Description
Resistance to antiviral drug(s)
Same as the full description in the CMS dataset.
Parent Code
Z16.3
Resistance to other antimicrobial drugs

Code Classification

ChapterZ00–Z99Factors influencing health status and contact with health services
SectionZ16Resistance to antimicrobial drugs
CategoryZ16Resistance to antimicrobial drugs
This CodeZ16.33Resistance to antiviral drug(s)

Code EditsBilling

Medicare Code Editor checks that affect claim validity for Z16.33.

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.

  • Amantadine resistant virus present
  • Drug resistance
  • Drug resistance to antiretroviral therapy
  • Drug resistance to antiviral agent
  • Infection caused by antimicrobial resistant virus
  • Oseltamivir resistant virus present
  • Zanamivir resistant virus present

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Resistance, resistant(to)
      • organism (s)
        • to
          • drug
            • antiviral

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR FAC015
Resistance to antimicrobial drugs
Default principal diagnosis: inpatient No · outpatient Yes

Clinical InformationClinical

  • Drug Resistance

    diminished or failed response of an organism, disease or tissue to the intended effectiveness of a chemical or drug. it should be differentiated from drug tolerance which is the progressive diminution of the susceptibility of a human or animal to the effects of a drug, as a result of continued administration.

  • Drug Resistance, Bacterial

    the ability of bacteria to resist or to become tolerant to chemotherapeutic agents, antimicrobial agents, or antibiotics. this resistance may be acquired through gene mutation or foreign dna in transmissible plasmids (r factors).

  • Drug Resistance, Fungal

    the ability of fungi to resist or to become tolerant to chemotherapeutic agents, antifungal agents, or antibiotics. this resistance may be acquired through gene mutation.

  • Drug Resistance, Microbial

    the ability of microorganisms, especially bacteria, to resist or to become tolerant to chemotherapeutic agents, antimicrobial agents, or antibiotics. this resistance may be acquired through gene mutation or foreign dna in transmissible plasmids (r factors).

  • Drug Resistance, Multiple

    simultaneous resistance to several structurally and functionally distinct drugs.

  • Drug Resistance, Multiple, Bacterial

    the ability of bacteria to resist or to become tolerant to several structurally and functionally distinct drugs simultaneously. this resistance may be acquired through gene mutation or foreign dna in transmissible plasmids (r factors).

  • Drug Resistance, Multiple, Fungal

    the ability of fungi to resist or to become tolerant to several structurally and functionally distinct drugs simultaneously. this resistance phenotype may be attributed to multiple gene mutations.

  • Drug Resistance, Multiple, Viral

    the ability of viruses to resist or to become tolerant to several structurally and functionally distinct drugs simultaneously. this resistance phenotype may be attributed to multiple gene mutation.

  • Drug Resistance, Neoplasm

    resistance or diminished response of a neoplasm to an antineoplastic agent in humans, animals, or cell or tissue cultures.

  • Drug Resistance, Viral

    the ability of viruses to resist or to become tolerant to chemotherapeutic agents or antiviral agents. this resistance is acquired through gene mutation.

  • Drug Tolerance

    progressive diminution of the susceptibility of a human or animal to the effects of a drug, resulting from its continued administration. it should be differentiated from drug resistance wherein an organism, disease, or tissue fails to respond to the intended effectiveness of a chemical or drug. it should also be differentiated from maximum tolerated dose and no-observed-adverse-effect level.

Convert Z16.33 to ICD-9-CMHistory

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

ICD-9-CM
V09.80 Inf mcr rst ot drg nt ml
Approximate The match is approximate rather than exact.

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 Z16.33Overview

Is Z16.33 (Resistance to other antimicrobial drugs) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report resistance to antiviral drug(s) on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does Z16.33 group to?

On inpatient claims, resistance to antiviral drug(s) maps to MS-DRG 867, 868, 869, with relative weights from 0.7297 to 2.0932 depending on complications. Higher weights mean higher Medicare reimbursement.

Can Z16.33 be a principal diagnosis?

No. The Medicare Code Editor rejects this code as a principal diagnosis because resistance to antiviral drug(s) 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 Z16.33?

Under the General Equivalence Mappings, resistance to antiviral drug(s) converts to ICD-9-CM V09.80 (inf mcr rst ot drg nt ml). The mapping is approximate, so confirm the match fits the documentation.