2027 ICD-10-CM Diagnosis Code Z51.6Encounter for desensitization to allergens

ICD-10-CM Codes›Z00–Z99›Z40-Z53›Z51

ICD-10-CM Z51.6
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

Z51.6 is a billable ICD-10-CM diagnosis code for encounter for desensitization to allergens. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 951. The code is not accepted as a principal diagnosis by the Medicare Code Editor and exempt from POA reporting. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other aftercare encounter.

Code Identity

ICD-10-CM Code
Z51.6
Billable Status
Yes — Valid for Submission
Code Describes
Encounter for desensitization to allergens
Short Description
Encounter for desensitization to allergens
Same as the full description in the CMS dataset.
Parent Code
Z51
Encounter for other aftercare and medical care

Code Classification

ChapterZ00–Z99Factors influencing health status and contact with health services
SectionZ40-Z53Encounters for other specific health care
CategoryZ51Encounter for other aftercare and medical care
This CodeZ51.6Encounter for desensitization to allergens

Code EditsBilling

Medicare Code Editor checks that affect claim validity for Z51.6.

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.

Present on Admission (POA)Billing

Z51.6 is exempt from POA reporting on inpatient claims to general acute care hospitals. Review the other POA exempt codes in Encounters for other specific health care (Z40-Z53).

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to Z51.6: its own notes plus those printed at Z51, block Z40-Z53, and Chapter 21. A note printed at a category, block or chapter applies to every code under it.

Excludes1

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

From Z51 Encounter for other aftercare and medical care applies to 8 codes
  • follow-up examination after treatment (Z08-Z09)

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From Block Z40-Z53 Encounters for other specific health care applies to 164 codes
  • follow-up examination for medical surveillance after treatment (Z08-Z09)

Code Also

A second code may be needed to fully describe the condition; the note gives no sequencing direction.

From Z51 Encounter for other aftercare and medical care applies to 8 codes
  • condition requiring care

Notes

General instructions on how these codes are used.

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 Z51.6, its category, or a range that includes it.

Excludes1 3

These codes carry an Excludes1 note naming Z51.6: they are not reported together with it, unless the two conditions are unrelated.

  • Z29 Encounter for other prophylactic measures
    desensitization to allergens (Z51.6)
  • Z08 Encounter for follow-up examination after completed treatment for malignant neoplasm
    aftercare following medical care (Z43-Z49, Z51) names Z51, which includes this code
  • Z09 Encounter for follow-up examination after completed treatment for conditions other than malignant neoplasm
    aftercare following medical care (Z43-Z49, Z51) names Z51, which includes this code

Excludes2 1

These codes carry an Excludes2 note naming Z51.6: its condition is not part of those codes, and both may be reported when the patient has both.

  • Z98 Other postprocedural states
    aftercare (Z43-Z49, Z51) names Z51, 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 FAC010
Other aftercare encounter
Default principal diagnosis: inpatient No · outpatient Yes

Convert Z51.6 to ICD-9-CMHistory

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

ICD-9-CM
V07.1 Desensitiza to allergens
Exact Match The mapping is direct, with no qualifiers.

Code History & ChangesHistory

Replacement Z51.6 replaces the following previously assigned code(s):

  • Z76.89 - Persons encountering health services in oth circumstances
FY 2019AddedAdded to the ICD-10-CM code setEffective October 1, 2018.
FY 2020–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About Z51.6Overview

What is the ICD-10 code for encounter for desensitization to allergens?

The ICD-10-CM code for encounter for desensitization to allergens is Z51.6 (sometimes written as Z516). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is Z51.6 (Encounter for other aftercare and medical care) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report encounter for desensitization to allergens on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does Z51.6 group to?

On inpatient claims, encounter for desensitization to allergens maps to MS-DRG 951 (other Factors Influencing Health Status), which carries a relative weight of 0.5574. Higher weights mean higher Medicare reimbursement.

Can Z51.6 be a principal diagnosis?

No. The Medicare Code Editor rejects this code as a principal diagnosis because encounter for desensitization to allergens describes a circumstance that influences health status rather than a current illness. Report it as a secondary diagnosis.

Is Z51.6 exempt from POA reporting?

Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for encounter for desensitization to allergens on inpatient claims. The code appears in the Encounters for other specific health care (Z40-Z53) range of the CMS exempt list.