2026 ICD-10-CM Diagnosis Code D84.821Immunodeficiency due to drugs

ICD-10-CM Codes›D50–D89›D80-D89›D84

ICD-10-CM D84.821
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

D84.821 is a billable ICD-10-CM diagnosis code for immunodeficiency due to drugs. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 814 through 816. Coders also document this condition as drug-induced immunodeficiency. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Immunity disorders.

Code Identity

ICD-10-CM Code
D84.821
Billable Status
Yes — Valid for Submission
Code Describes
Immunodeficiency due to drugs
Short Description
Immunodeficiency due to drugs
Same as the full description in the CMS dataset.
Parent Code
D84.82
Immunodeficiency due to drugs and external causes

Code Classification

ChapterD50–D89Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism
SectionD80-D89Certain disorders involving the immune mechanism
CategoryD84Other immunodeficiencies
This CodeD84.821Immunodeficiency due to drugs

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Drug-induced immunodeficiency
  • Immunodeficiency caused by long term therapeutic use of drug
  • Immunodeficiency caused by long term therapeutic use of immunosuppressant

Tabular List NotesGuidance

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

Inclusion Terms

  • Immunodeficiency due to (current or past) medication

Use Additional Code

  • code for adverse effect if applicable, to identify adverse effect of drug T36 T50

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.

    • Immunodeficiency
      • due to
        • drugs
    • Immunodeficiency
      • due to
        • medication (current or past)

Clinical ClassificationClinical

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

CCSR BLD008
Immunity disorders
Default principal diagnosis: inpatient Yes · outpatient Yes

Code History & ChangesHistory

Replacement D84.821 replaces the following previously assigned code(s):

  • D84.8 - Other specified immunodeficiencies
FY 2021AddedAdded to the ICD-10-CM code setEffective October 1, 2020.
FY 2022–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About D84.821Overview

Is D84.821 (Immunodeficiency due to drugs and external causes) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report immunodeficiency due to drugs on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does D84.821 group to?

When immunodeficiency due to drugs is the principal diagnosis on an inpatient stay, it groups to MS-DRG 814, 815, 816, with relative weights from 0.6320 to 2.1267 depending on complications. Higher weights mean higher Medicare reimbursement.

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.