F18.959 ICD-10-CM Code: Inhalant use, unspecified with inhalant-induced psychotic disorder, unspecified
F18.959 maps to CMS-HCC V28 135. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · HCC coding software
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FY 2026 Apr update / Mental, Behavioral and Neurodevelopmental disorders (F01-F99) / Mental and behavioral disorders due to psychoactive substance use (F10-F19)
F18.959
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceInhalant use, unspecified with inhalant-induced psychotic disorder, unspecified
A person with inhalant use (not dependent) experiencing psychotic symptoms from inhalants, but the specific type of psychotic disorder is not specified.
Buddy Insight
This code captures substance-induced psychotic disorder, which represents a serious psychiatric complication of inhalant use.
CMS-HCC V28
MappedHCC 135
Code-level coefficient reference
CMS-HCC V24
HistoricalHistorical
Not used for CY2026 payment
ACA/HHS
MappedHCC 081
Code-level coefficient reference
ESRD/PACE
MappedHCC 54
Code-level coefficient reference
RXHCC
N/A—
Not mapped
Code Book Path
Inclusion Terms
OfficialNo inclusion terms are included in this display for F18.959. 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
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
OfficialNo Code First sequencing instructions are included in this display for F18.959. Check the code and parent instructions in the Code Book.
Use Additional
OfficialNo Use Additional Code instructions are included in this display for F18.959. Check the code and parent instructions in the Code Book.
Code Also
OfficialNo Code Also instructions are included in this display for F18.959. Check the code and parent instructions in the Code Book.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
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 F18.959 an HCC code?
Yes. F18.959 (Inhalant use, unspecified with inhalant-induced psychotic disorder, unspecified) maps to HCC 135, Drug Use with 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: F18.959 is billable and maps to V28 HCC 135, Drug Use with Psychotic Complications. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.
- Code
- F18.959
- Description
- Inhalant use, unspecified with inhalant-induced psychotic disorder, unspecified
- HCC (V28)
- HCC 135 — Drug Use with Psychotic Complications
- RAF reference coefficient
- 0.424
- Billable
- Yes
- Payment year
- 2026
HCC Category Mapping
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 F18.959 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →
MEAT review for F18.959
For F18.959, 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
F18.959 is the ICD-10-CM diagnosis code for inhalant use, unspecified with inhalant-induced psychotic disorder, unspecified. A person with inhalant use (not dependent) experiencing psychotic symptoms from inhalants, but the specific type of psychotic disorder is not specified. F18.959 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, F18.959 maps to Drug Use with Psychotic Complications (HCC 135) with a source-labeled community, non-dual, aged reference coefficient of 0.424. No V24 mapping is shown for F18.959; 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 whether hallucinations, delusions, or both are present to potentially use more specific codes. For F18.959, 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 F18.959 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Document whether hallucinations, delusions, or both are present to potentially use more specific codes
- •Verify the psychotic symptoms are inhalant-induced rather than a primary psychotic disorder
Clinical Significance
This code captures substance-induced psychotic disorder, which represents a serious psychiatric complication of inhalant use. Substance-induced psychosis significantly increases healthcare utilization, emergency department visits, and hospitalization risk, making accurate capture critical for risk adjustment. These patients require intensive psychiatric management and close monitoring for progression to chronic psychotic disorders.
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 psychotic symptoms (delusions and/or hallucinations) with provider statement that they are substance-induced rather than a primary psychotic disorder
- ✓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
- •F18.94 / F18.14 / F18.24 (Inhalant-induced mood disorder): mood disorder presents with depression or mania, not psychotic features like delusions or hallucinations
- •F19.x codes (Other psychoactive substance use): F19 is for substances other than inhalants; use F18 specifically when the substance is an inhalant