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F18.921 ICD-10-CM Code: Inhalant use, unspecified with intoxication with delirium

F18.921 maps to CMS-HCC V28 137. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · free HCC coding tools

ICD-10-CM Code View

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Digital ICD-10 code-book layout with official code detail, always-visible risk models, Code Trumping, and Buddy coding guidance.

Code lookupF18.921

FY 2026 Apr update / Mental, Behavioral and Neurodevelopmental disorders (F01-F99) / Mental and behavioral disorders due to psychoactive substance use (F10-F19)

F18.921

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Inhalant use, unspecified with intoxication with delirium

A person using inhalants without dependence who is currently intoxicated and experiencing delirium (confusion, disorientation, and altered consciousness).

Buddy the Bee presenting code insight

Buddy Insight

This code identifies intoxication delirium from inhalant use, a severe acute presentation with altered consciousness, disorientation, and potential for dangerous behavior.

OverviewRisk ModelsCode BookDocumentationAuditNotesEdition comparison

CMS-HCC V28

HCC 137

Coefficient HCC 137: 0.424 (Community Non-Dual Aged (CNA))

CMS-HCC V24

Historical

Historical

Not used for CY2026 payment

ACA/HHS

HCC 082

Code-level coefficient reference

ESRD/PACE

HCC 55

Code-level coefficient reference

RXHCC

N/A

—

Not mapped

Code Book Path

Official
F18.9Inhalant use, unspecifiedF18.92Inhalant use, unspecified with intoxicationF18.921Inhalant use, unspecified with intoxication with delirium

Inclusion Terms

Official

No inclusion terms are included in this display for F18.921. Check the code and parent instructions in the Code Book.

Excludes 2

Official
  • symptoms, signs and abnormal clinical laboratory findings, not elsewhere classified (R00-R99)Inherited from F01-F99

Related Codes

Official
F18.920Inhalant use, unspecified with intoxication, uncomplicatedF18.929Inhalant use, unspecified with intoxication, unspecified

Includes

Official
  • disorders of psychological developmentInherited from F01-F99, F18
  • volatile solventsInherited from F01-F99, F18

Excludes 1

Official
  • inhalant abuse (F18.1-)Inherited from F18.9
  • inhalant dependence (F18.2-)Inherited from F18.9

Code First

Official

No Code First sequencing instructions are included in this display for F18.921. Check the code and parent instructions in the Code Book.

Use Additional

Official

No Use Additional Code instructions are included in this display for F18.921. Check the code and parent instructions in the Code Book.

Code Also

Official

No Code Also instructions are included in this display for F18.921. Check the code and parent instructions in the Code Book.

Buddy Documentation Tip

HCC Buddy guidance
Provider documentation of inhalant use, specifying the type of inhalant when known (e.g., toluene, gasoline, aerosol propellants, nitrites)
Documentation of substance use pattern; query provider to determine if abuse or dependence criteria are met for more specific coding
Documentation of acute intoxication state with signs and symptoms present at the time of encounter
Clinical findings supporting delirium: acute onset of confusion, fluctuating consciousness, disorientation, and cognitive disturbance temporally related to substance intoxication

MEAT Support

HCC Buddy guidance
Provider documentation of inhalant use, specifying the type of inhalant when known (e.g., toluene, gasoline, aerosol propellants, nitrites)
Documentation of substance use pattern; query provider to determine if abuse or dependence criteria are met for more specific coding
Documentation of acute intoxication state with signs and symptoms present at the time of encounter
Clinical findings supporting delirium: acute onset of confusion, fluctuating consciousness, disorientation, and cognitive disturbance temporally related to substance intoxication

Audit Caution

HCC Buddy guidance
Failing to identify inhalant use as the specific substance category — F18 codes are specifically for inhalants and should not be used for other volatile substance exposures like occupational chemical exposure
Defaulting to unspecified use (F18.9x) without querying the provider for clarification on whether the patient meets criteria for abuse (F18.1x) or dependence (F18.2x)
Confusing delirium with simple intoxication or perceptual disturbances — delirium requires documented acute onset of confusion, fluctuating consciousness, and disorientation

Common Mistakes

HCC Buddy guidance
F18.10-F18.19 (Inhalant abuse codes) — use when documentation supports a pattern of harmful use without dependence
F18.20-F18.29 (Inhalant dependence codes) — use when documentation supports physiological or psychological dependence
F18.920 / F18.120 / F18.220 (Inhalant intoxication, uncomplicated) — uncomplicated intoxication lacks the acute confusion and altered consciousness seen in delirium
F19.x codes (Other psychoactive substance use) — F19 is for substances other than inhalants; use F18 specifically when the substance is an inhalant

Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →

Is F18.921 an HCC code?

Yes. F18.921 (Inhalant use, unspecified with intoxication with delirium) maps to HCC 137, Drug Use Disorder, Moderate/Severe, or Drug Use with Non-Psychotic Complications under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.424. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes. It is billable for payment year 2026.

Coder answer: F18.921 is billable and maps to V28 HCC 137, Drug Use Disorder, Moderate/Severe, or Drug Use with Non-Psychotic Complications. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code
F18.921
Description
Inhalant use, unspecified with intoxication with delirium
HCC (V28)
HCC 137 — Drug Use Disorder, Moderate/Severe, or Drug Use with Non-Psychotic Complications
RAF reference coefficient
0.424
Billable
Yes
Payment year
2026

HCC Category Mapping

V28HCC 137, Drug Use Disorder, Moderate/Severe, or Drug Use with Non-Psychotic Complications
0.424
ESRDHCC 55, Substance Use Disorder/Moderate/Severe/Substance Use with Complications
Not separately weighted

These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. Weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.

Work F18.921 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT review for F18.921

For F18.921, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.

  • MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
  • EEvaluate: test results, medication response, or physical findings reviewed by the provider
  • AAssess: explicit mention in the assessment or plan with acknowledgment of status
  • TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis

Coder workflow notes

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What This Code Means

F18.921 is the ICD-10-CM diagnosis code for inhalant use, unspecified with intoxication with delirium. A person using inhalants without dependence who is currently intoxicated and experiencing delirium (confusion, disorientation, and altered consciousness). F18.921 sits in the ICD-10-CM chapter for mental, behavioral and neurodevelopmental disorders (f01-f99), within the section covering mental and behavioral disorders due to psychoactive substance use (f10-f19).

Under the CMS-HCC V28 risk adjustment model, F18.921 maps to Drug Use Disorder, Moderate/Severe, or Drug Use with Non-Psychotic Complications (HCC 137) with a source-labeled community, non-dual, aged reference coefficient of 0.424. No V24 mapping is shown for F18.921; use the applicable model and payment year when reviewing the V28 mapping. For CY2026 non-PACE Medicare Advantage, CMS uses 100% of the 2024 CMS-HCC model (V28). PACE uses a separate model blend. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes.

Document specific delirium symptoms such as confusion, disorientation, or altered mental status. For F18.921, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.

HCC Buddy maintains structured V28 and V24 mapping, source-labeled coefficient references, and MEAT documentation criteria for F18.921 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

  • •Document specific delirium symptoms such as confusion, disorientation, or altered mental status
  • •Distinguish from F18.920 by confirming presence of delirium complications

Clinical Significance

This code identifies intoxication delirium from inhalant use, a severe acute presentation with altered consciousness, disorientation, and potential for dangerous behavior. Intoxication delirium often requires emergency department evaluation and potential hospitalization for medical stabilization. Capturing this code accurately reflects the elevated acuity and resource intensity of these encounters.

Documentation Requirements

  • ✓Provider documentation of inhalant use, specifying the type of inhalant when known (e.g., toluene, gasoline, aerosol propellants, nitrites)
  • ✓Documentation of substance use pattern; query provider to determine if abuse or dependence criteria are met for more specific coding
  • ✓Documentation of acute intoxication state with signs and symptoms present at the time of encounter
  • ✓Clinical findings supporting delirium: acute onset of confusion, fluctuating consciousness, disorientation, and cognitive disturbance temporally related to substance intoxication
  • ✓Assessment and plan addressing the substance use disorder with treatment approach documented

Commonly Confused Codes

  • •F18.10-F18.19 (Inhalant abuse codes): use when documentation supports a pattern of harmful use without dependence
  • •F18.20-F18.29 (Inhalant dependence codes): use when documentation supports physiological or psychological dependence
  • •F18.920 / F18.120 / F18.220 (Inhalant intoxication, uncomplicated): uncomplicated intoxication lacks the acute confusion and altered consciousness seen in delirium
  • •F19.x codes (Other psychoactive substance use): F19 is for substances other than inhalants; use F18 specifically when the substance is an inhalant

Child Codes

F18.920Inhalant use, unspecified with intoxication, uncomplicated
HCC 137
F18.921Inhalant use, unspecified with intoxication with delirium
HCC 137
F18.929Inhalant use, unspecified with intoxication, unspecified
HCC 137

Code Hierarchy

└F18Inhalant related disorders└F18.9Inhalant use, unspecified└F18.92Inhalant use, unspecified with intoxication└F18.921Inhalant use, unspecified with intoxication with delirium
└F18.921Inhalant use, unspecified with intoxication with delirium

Also searched as

  • F18 921
  • F18921

For F18.921, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.

F18.921 maps to CMS-HCC V28 category 137, Drug Use Disorder, Moderate/Severe, or Drug Use with Non-Psychotic Complications. See the ICD-10 to HCC mapping hub for how the V28 crosswalk works. The mapping identifies a payment HCC category for F18.921. Review its source-labeled HCC coefficient above, check the RAF Calculator with complete member context for CMS-HCC V28 PY2026, and confirm the documentation the chart needs before the code is submitted. HCC Buddy shows no RAF score unless every required source and calculation check passes.

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