2026 ICD-10-CM Diagnosis Code Z16.31Resistance to antiparasitic drug(s)

ICD-10-CM Codes›Z00–Z99›Z16›Z16

ICD-10-CM Z16.31
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

Z16.31 is a billable ICD-10-CM diagnosis code for resistance to antiparasitic 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. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Resistance to antimicrobial drugs.

Code Identity

ICD-10-CM Code
Z16.31
Billable Status
Yes — Valid for Submission
Code Describes
Resistance to antiparasitic drug(s)
Short Description
Resistance to antiparasitic 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 CodeZ16.31Resistance to antiparasitic drug(s)

Code EditsBilling

Medicare Code Editor checks that affect claim validity for Z16.31.

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.

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Resistance to quinine and related compounds

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
            • antiparasitic
    • Resistance, resistant(to)
      • organism (s)
        • to
          • drug
            • quinine (and related compounds)

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

Convert Z16.31 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 Z16.31Overview

Is Z16.31 (Resistance to other antimicrobial drugs) a billable code?

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

What MS-DRG does Z16.31 group to?

On inpatient claims, resistance to antiparasitic 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 Z16.31 be a principal diagnosis?

No. The Medicare Code Editor rejects this code as a principal diagnosis because resistance to antiparasitic 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 Z16.31?

Under the General Equivalence Mappings, resistance to antiparasitic 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.