2027 ICD-10-CM Diagnosis Code F18.921Inhalant use, unspecified with intoxication with delirium
ICD-10-CM Codes›F01–F99›F10-F19›F18
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Risk Adjusts — HCC 137
- Not Chronic
F18.921 is a billable ICD-10-CM diagnosis code for inhalant use, unspecified with intoxication with delirium. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 894 through 897. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 463 closely related codes. Coders also document this condition as inhalant intoxication delirium. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Inhalant-related disorders.
For Medicare Advantage risk adjustment, F18.921 maps to CMS-HCC Category 137 (Drug Use Disorder, Moderate/Severe, or Drug Use with Non-Psychotic Complications) under the V28 model, adding a risk factor of about 0.424 for a community, non-dual, aged beneficiary in payment year 2027.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
F18.921 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2027.
Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Inhalant intoxication delirium
- Intoxication caused by inhalant
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to F18.921: its own notes plus those printed at F18.9, F18, and Chapter 5. A note printed at a category, block or chapter applies to every code under it.
Includes
Further defines, or gives examples of, the content of the category.
- volatile solvents
- disorders of psychological development
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
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.
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name F18.921, its category, or a range that includes it.
Excludes1 2
These codes carry an Excludes1 note naming F18.921: they are not reported together with it, unless the two conditions are unrelated.
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.
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 F18.921 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About F18.921Overview
What is the ICD-10 code for inhalant use, unspecified with intoxication with delirium?
The ICD-10-CM code for inhalant use, unspecified with intoxication with delirium is F18.921 (sometimes written as F18921). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is F18.921 (Inhalant use, unspecified with intoxication) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report inhalant use, unspecified with intoxication with delirium on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does F18.921 group to?
When inhalant use, unspecified with intoxication with delirium is the principal diagnosis on an inpatient stay, it groups to MS-DRG 894, 897, 895, 896, with relative weights from 0.6272 to 1.6610 depending on complications. Higher weights mean higher Medicare reimbursement.
Is F18.921 a CC or MCC?
CMS lists F18.921 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 463 closely related codes in its exclusion list.
Can F18.921 be reported with a code from F18.1?
Not as a rule. The Excludes1 note at F18.9, which applies to F18.921, lists "inhalant abuse (F18.1-)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
What HCC is F18.921?
F18.921 (inhalant use, unspecified with intoxication with delirium) maps to CMS-HCC Category 137 (Drug Use Disorder, Moderate/Severe, or Drug Use with Non-Psychotic Complications), commonly written as HCC 137, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 55 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. It does not map to any RxHCC in the Part D prescription drug model.
Does F18.921 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, F18.921 adds a risk adjustment factor of about 0.424 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.297 to 0.502 depending on the payment segment). A more severe related category (HCC 135 and HCC 136) supersedes it when both are reported. See the full factor table on the HCC 137 category page.
