2026 ICD-10-CM Diagnosis Code F16.921Hallucinogen use, unspecified with intoxication with delirium

ICD-10-CM Codes›F01–F99›F10-F19›F16

ICD-10-CM F16.921
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

F16.921 is a billable ICD-10-CM diagnosis code for hallucinogen use, unspecified with intoxication with delirium. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 894 through 897. Coders also document this condition as delirium caused by hallucinogen. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Hallucinogen-related disorders.

Code Identity

ICD-10-CM Code
F16.921
Billable Status
Yes — Valid for Submission
Code Describes
Hallucinogen use, unspecified with intoxication with delirium
Short Description
Hallucinogen use, unsp with intoxication with delirium
Parent Code
F16.92
Hallucinogen use, unspecified with intoxication

Code Classification

ChapterF01–F99Mental and behavioural disorders
SectionF10-F19Mental and behavioral disorders due to psychoactive substance use
CategoryF16Hallucinogen related disorders
This CodeF16.921Hallucinogen use, unspecified with intoxication with delirium

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Delirium caused by hallucinogen
  • Hallucinogen intoxication delirium

Tabular List NotesGuidance

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

Inclusion Terms

  • Other hallucinogen intoxication delirium

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.

    • Delirium, delirious(acute or subacute) (not alcohol- or drug-induced)
      • due to (secondary to)
        • hallucinogen intoxication
    • Delirium, delirious(acute or subacute) (not alcohol- or drug-induced)
      • due to (secondary to)
        • phencyclidine intoxication (acute)
    • Use(of)
      • hallucinogen NEC
        • with
          • intoxication
            • with
              • delirium

Clinical ClassificationClinical

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

CCSR MBD022
Hallucinogen-related disorders
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Delirium

Delirium is a mental state in which you are confused, disoriented, and not able to think or remember clearly. It usually starts suddenly. It is often temporary and treatable.

The full article covers:

  • What is delirium?
  • What causes delirium?
  • Who is more likely to get delirium?
  • What are the symptoms of delirium?
  • How is delirium diagnosed?
  • What are the treatments for delirium?
  • Can delirium be prevented?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert F16.921 to ICD-9-CMHistory

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

ICD-9-CM
292.81 Drug-induced delirium
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 F16.921Overview

Is F16.921 (Hallucinogen use, unspecified with intoxication) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report hallucinogen use, unspecified with intoxication with delirium on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does F16.921 group to?

When hallucinogen use, unspecified with intoxication with delirium is the principal diagnosis on an inpatient stay, it groups to MS-DRG 894, 895, 896, 897, with relative weights from 0.6169 to 1.7451 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of F16.921?

Under the General Equivalence Mappings, hallucinogen use, unspecified with intoxication with delirium converts to ICD-9-CM 292.81 (drug-induced delirium). The mapping is approximate, so confirm the match fits the documentation.

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.