What is ICD-10 code F15.921?

F15.921 is the ICD-10-CM diagnosis code for Other stimulant use, unspecified with intoxication delirium. A person using stimulant drugs who is currently intoxicated and experiencing delirium, a state of confusion and disorientation caused by the acute drug effects. F15.921 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. F15.921 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. F15.921 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. F15.921 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

Which HCC does F15.921 map to under V28?

F15.921 maps to CMS-HCC V28 HCC 137 (Drug Use Disorder, Moderate/Severe, or Drug Use with Non-Psychotic Complications). The category numbers, labels, and conditions come from the CMS-HCC V28 model file for payment year 2026.

What documentation supports F15.921?

Document specific delirium symptoms (confusion, disorientation, altered consciousness) to justify this more severe code Consider monitoring for medical complications and safety risks associated with stimulant-induced delirium Because F15.921 maps to an HCC category, the documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) before the diagnosis is used for risk adjustment. See the MEAT criteria checklist at /meat-criteria for what Monitor, Evaluate, Assess, or Treat looks like in a note. MEAT is generic documentation evidence, not a payer-specific rule.

2026 ICD-10-CM F15.921: Other stimulant use

F15.921 maps to CMS-HCC V28 137. A source-labeled RAF reference is available. Documentation must support MEAT. 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 lookupF15.921Effective periodFY2026 Apr Update (Apr 1-Sep 30)

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

F15.921

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

Other stimulant use, unspecified with intoxication delirium

A person using stimulant drugs who is currently intoxicated and experiencing delirium, a state of confusion and disorientation caused by the acute drug effects.

Buddy Insight

Stimulant use, unspecified with intoxication delirium is a high-acuity presentation requiring emergency medical management.

CMS-HCC V28

Mapped

HCC 137

Drug Use Disorder, Moderate/S...

Code-level coefficient reference

CMS-HCC V24

Historical

Not used for standard CY2026 Medicare Advantage payment. Select a historical period to review V24.

Not used for CY2026 payment

ACA/HHS

Mapped

HCC 082

HHS-HCC 082 adult, RAF varies...

Code-level coefficient reference

ESRD/PACE

Mapped

HCC 55

Substance Use Disorder/Modera...

Code-level coefficient reference

RXHCC

N/A

—

Not risk-adjusted for this model/period.

Not mapped

Code Book Path

Official

F15.9Other stimulant use, unspecified

F15.92Other stimulant use, unspecified with intoxication

F15.921Other stimulant use, unspecified with intoxication delirium

Inclusion Terms

Official

Amphetamine or other stimulant-induced delirium

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for F15.921 in this effective period.

Related Child Codes

Official

F15.920Other stimulant use, unspecified with intoxication, uncomplicated

F15.922Other stimulant use, unspecified with intoxication with perceptual disturbance

F15.929Other stimulant use, unspecified with intoxication, unspecified

Includes

Official

ICD-10-CM does not list Includes notes for F15.921 in this effective period.

Excludes 1

Official

other stimulant use, unspecified with withdrawal (F15.93)

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for F15.921 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for F15.921 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for F15.921 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Documentation of stimulant use

Clinical evidence of acute intoxication

Specific documentation of delirium: acute confusion, altered consciousness, disorientation

Vital signs and laboratory findings (elevated temperature, heart rate, CK levels)

MEAT Support

HCC Buddy guidance

Documentation of stimulant use

Clinical evidence of acute intoxication

Specific documentation of delirium: acute confusion, altered consciousness, disorientation

Vital signs and laboratory findings (elevated temperature, heart rate, CK levels)

Audit Caution

HCC Buddy guidance

Coding uncomplicated intoxication when delirium criteria are met

Not recognizing delirium presentation in the context of stimulant intoxication

Using a non-substance-related delirium code when stimulant intoxication is the cause

Failing to document specific delirium criteria (altered consciousness, confusion, disorientation)

Common Mistakes

HCC Buddy guidance

F15.920 — Stimulant use, unspecified with uncomplicated intoxication; no delirium

F15.922 — Stimulant use, unspecified with perceptual disturbance; perceptual changes without full delirium

F15.221 — Stimulant dependence with intoxication delirium; use when dependence is documented

F05 — Delirium due to known physiological condition; non-substance-induced delirium

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 F15.921 an HCC code?

Yes. F15.921 (Other stimulant use, unspecified with intoxication 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: F15.921 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: F15.921
Description: Other stimulant use, unspecified with intoxication 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 F15.921 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT Criteria for F15.921

For F15.921 to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically, it has to be re-documented and supported each calendar year.

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

Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed F15.921 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

F15.921 is the ICD-10-CM diagnosis code for other stimulant use, unspecified with intoxication delirium. A person using stimulant drugs who is currently intoxicated and experiencing delirium, a state of confusion and disorientation caused by the acute drug effects. F15.921 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, F15.921 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 F15.921; use the applicable model and payment year when reviewing the V28 mapping. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition. 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 (confusion, disorientation, altered consciousness) to justify this more severe code. Because F15.921 maps to an HCC category, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) before the diagnosis is used for risk adjustment. 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 F15.921 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Document specific delirium symptoms (confusion, disorientation, altered consciousness) to justify this more severe code
•Consider monitoring for medical complications and safety risks associated with stimulant-induced delirium

Clinical Significance

Stimulant use, unspecified with intoxication delirium is a high-acuity presentation requiring emergency medical management. Delirium during stimulant intoxication indicates severe neuropsychiatric toxicity with altered consciousness, confusion, and potential for life-threatening complications including hyperthermia and cardiovascular collapse. This code is commonly used in acute care settings where the use pattern is not yet characterized.

Documentation Requirements

✓Documentation of stimulant use
✓Clinical evidence of acute intoxication
✓Specific documentation of delirium: acute confusion, altered consciousness, disorientation
✓Vital signs and laboratory findings (elevated temperature, heart rate, CK levels)
✓Emergency interventions performed and level of care provided

Commonly Confused Codes

•F15.920: Stimulant use, unspecified with uncomplicated intoxication; no delirium
•F15.922: Stimulant use, unspecified with perceptual disturbance; perceptual changes without full delirium
•F15.221: Stimulant dependence with intoxication delirium; use when dependence is documented
•F05: Delirium due to known physiological condition; non-substance-induced delirium