2027 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 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

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 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 867 through 869. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. 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.

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to Z16.31: its own notes plus those printed at Z16.3, Z16, and Chapter 21. A note printed at a category, block or chapter applies to every code under it.

Applicable To

Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.

  • Resistance to quinine and related compounds

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

From Z16.3 Resistance to other antimicrobial drugs applies to 8 codes
From Z16 Resistance to antimicrobial drugs applies to 19 codes
  • Methicillin resistant Staphylococcus aureus infection (A49.02)
  • Methicillin resistant Staphylococcus aureus pneumonia (J15.212)
  • Sepsis due to Methicillin resistant Staphylococcus aureus (A41.02)

Code First

The underlying condition named in the note is sequenced before this code.

From Z16 Resistance to antimicrobial drugs applies to 19 codes
  • the infection

Notes

General instructions on how these codes are used.

From Z16 Resistance to antimicrobial drugs applies to 19 codes
  • The codes in this category are provided for use as additional codes to identify the resistance and non-responsiveness of a condition to antimicrobial drugs.
From Chapter 21 (Z00-Z99) Factors influencing health status and contact with health services applies to 1,425 codes
  • Z codes represent reasons for encounters. A corresponding procedure code must accompany a Z code if a procedure is performed. Categories Z00-Z99 are provided for occasions when circumstances other than a disease, injury or external cause classifiable to categories A00-Y89 are recorded as 'diagnoses' or 'problems'. This can arise in two main ways:
  • (a) When a person who may or may not be sick encounters the health services for some specific purpose, such as to receive limited care or service for a current condition, to donate an organ or tissue, to receive prophylactic vaccination (immunization), or to discuss a problem which is in itself not a disease or injury.
  • (b) When some circumstance or problem is present which influences the person's health status but is not in itself a current illness or injury.

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name Z16.31, its category, or a range that includes it.

Use Additional Code 2

These codes say to use an additional code from the note, and Z16.31 is one of the codes named.

  • Chapter 1 (A00-B99) Certain infectious and parasitic diseases
    code to identify resistance to antimicrobial drugs (Z16.-) names Z16.-, which includes this code
  • Block J09-J18 Influenza and pneumonia
    code, if applicable, to identify resistance to antimicrobial drugs (Z16.-) names Z16.-, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

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 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About Z16.31Overview

What is the ICD-10 code for resistance to antiparasitic drug(s)?

The ICD-10-CM code for resistance to antiparasitic drug(s) is Z16.31 (sometimes written as Z1631). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

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, 2026 through September 30, 2027.

What MS-DRG does Z16.31 group to?

On inpatient claims, resistance to antiparasitic drug(s) maps to MS-DRG 867, 869, 868, with relative weights from 0.6784 to 2.1855 depending on complications. Higher weights mean higher Medicare reimbursement.

Is Z16.31 a CC or MCC?

CMS lists Z16.31 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family.

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.