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T40.416D ICD-10-CM Code: Underdosing of fentanyl or fentanyl analogs, subsequent encounter

Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Inpatient Payment Groups (MS-DRG)

MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v43.0, Appendix B.

A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.

Code Overview

Underdosing of fentanyl or fentanyl analogs, subsequent encounter is a billable ICD-10-CM diagnosis code (T40.416D).

Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Official Tabular Instructional Notes

Sequencing, inclusion, and exclusion notes published for T40.416D in the official ICD-10-CM tabular list.

Includes

Conditions the official ICD-10-CM tabular list includes under this code.

  • adverse effect of correct substance properly administered inherited from T36-T50
  • poisoning by overdose of substance inherited from T36-T50
  • poisoning by wrong substance given or taken in error inherited from T36-T50
  • underdosing by (inadvertently) (deliberately) taking less substance than prescribed or instructed inherited from T36-T50

Excludes1 — Not Coded Here

Conditions generally not reported together with this code (Excludes1) -- an error unless the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).

Excludes2 — Not Included Here

Conditions not covered by this code, but which may be reported alongside it when both are present.

Code First

Underlying conditions that must be sequenced before this code.

  • Code first, for adverse effects, the nature of the adverse effect, such as: inherited from T36-T50
  • adverse effect NOS (T88.7) inherited from T36-T50
  • aspirin gastritis (K29.-) inherited from T36-T50
  • blood disorders (D56-D76) inherited from T36-T50
  • contact dermatitis (L23-L25) inherited from T36-T50
  • dermatitis due to substances taken internally (L27.-) inherited from T36-T50
  • nephropathy (N14.0-N14.2) inherited from T36-T50

Use Additional Code

Supplementary codes the tabular list directs you to add.

  • Use additional code(s) to specify: inherited from T36-T50
  • manifestations of poisoning inherited from T36-T50
  • underdosing or failure in dosage during medical and surgical care (Y63.6, Y63.8-Y63.9) inherited from T36-T50
  • underdosing of medication regimen (Z91.12-, Z91.13-) inherited from T36-T50

Associated Substances (3)

Substances from the official ICD-10-CM Table of Drugs and Chemicals that map to this code.

  • Alfentanil
  • Fentanyl (analogs)
  • Sufentanil

Frequently Compared Codes

The official Excludes notes on T40.416D name these codes. Each comparison page covers when the two can — or must not — be reported together.

Change history

  • FY2021 — 2020-10-01
    Added to the code set
    Underdosing of fentanyl or fentanyl analogs, subsequent encounter
    FY2021 changes

Verify Before Coding

  • Principal-diagnosis restriction. The Medicare Code Editor lists this code as unacceptable as a principal diagnosis: it describes a circumstance influencing health status rather than a current illness or injury being treated. It is valid as a secondary diagnosis.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MS-DRG Grouper Relationships (FY2026)

Not on the CMS CC/MCC list — as a secondary diagnosis this code does not change MS-DRG severity.

Named in the grouper logic of 2 MS-DRGs: DRG 949 (MDC 23), DRG 950 (MDC 23).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):INJ066 — Underdosing of drugs and medicaments, subsequent encounter.

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Principal diagnosis restriction (Medicare Code Editor)

Not acceptable as a principal diagnosis on an inpatient claim.

Same injury, other encounter phase

Same injury, coded at a different phase of treatment via the 7th character.

T40.416A — Underdosing of fentanyl or fentanyl analogs, initial encounter Compare T40.416D vs T40.416A →, T40.416S — Underdosing of fentanyl or fentanyl analogs, sequela

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Underdosing of drugs and medicaments, subsequent encounter).

T39.1X6D — Underdosing of 4-Aminophenol derivatives, subsequent encounter, T39.2X6D — Underdosing of pyrazolone derivatives, subsequent encounter, T39.316D — Underdosing of propionic acid derivatives, subsequent encounter, T39.396D — Underdosing of other nonsteroidal anti-inflammatory drugs [NSAID], subsequent encounter, T39.4X6D — Underdosing of antirheumatics, not elsewhere classified, subsequent encounter, T39.8X6D — Underdosing of other nonopioid analgesics and antipyretics, not elsewhere classified, subsequent encounter, T39.96XD — Underdosing of unspecified nonopioid analgesic, antipyretic and antirheumatic, subsequent encounter, T40.0X6D — Underdosing of opium, subsequent encounter, T40.2X6D — Underdosing of other opioids, subsequent encounter, T40.3X6D — Underdosing of methadone, subsequent encounter, T40.426D — Underdosing of tramadol, subsequent encounter, T40.496D — Underdosing of other synthetic narcotics, subsequent encounter, T40.5X6D — Underdosing of cocaine, subsequent encounter, T40.606D — Underdosing of unspecified narcotics, subsequent encounter, T40.696D — Underdosing of other narcotics, subsequent encounter, T40.716D — Underdosing of cannabis, subsequent encounter, T40.726D — Underdosing of synthetic cannabinoids, subsequent encounter, T40.906D — Underdosing of unspecified psychodysleptics [hallucinogens], subsequent encounter, T40.996D — Underdosing of other psychodysleptics [hallucinogens], subsequent encounter, T41.0X6D — Underdosing of inhaled anesthetics, subsequent encounter, +154 more

Lab tests where this diagnosis supports Medicare coverage (NCD)

Medicare's National Coverage Determination (NCD) program lists this diagnosis as medical justification for these lab tests.

Gamma-glutamyl Transferase (GGT) Test, Partial Thromboplastin Time (PTT) Test, Prothrombin Time Test and INR (PT/INR)

Contextual Map

Every relationship of T40.416D in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Hierarchy

  • S00-T88 — Chapter 19: Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88) (S00-T88) [Hierarchy]
  • T36-T50 — Poisoning by, adverse effects of and underdosing of drugs, medicaments and biological substances [Hierarchy]
  • T40-T41 — Analgesics & Antipyretics [Hierarchy]

Clinical classification (CCSR)

  • INJ066 — Underdosing of drugs and medicaments, subsequent encounter [CCSR]

MS-DRG Grouper

  • DRG 949 — AFTERCARE WITH CC/MCC [MS-DRG]: “AFTERCARE WITH CC/MCC (MDC 23)”
  • DRG 950 — AFTERCARE WITHOUT CC/MCC [MS-DRG]: “AFTERCARE WITHOUT CC/MCC (MDC 23)”

MDC crossing · procedures (1235)

  • MDC 23 — Factors Influencing Health Status and Other Contacts with Health Services [MDC crossing]: “Factors Influencing Health Status and Other Contacts with Health Services — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs.”
  • F003GKZ — Communicative/Cognitive Integration Skills Assessment of Neurological System - Whole Body using Audiovisual Equipment [Same-MDC procedure]: “Communicative/Cognitive Integration Skills Assessment of Neurological System - Whole Body using Audiovisual Equipment — grouped in MDC 23, the procedure side of this code's crossing.” · check together
  • F003GMZ — Communicative/Cognitive Integration Skills Assessment of Neurological System - Whole Body using Augmentative / Alternative Communication Equipment [Same-MDC procedure]: “Communicative/Cognitive Integration Skills Assessment of Neurological System - Whole Body using Augmentative / Alternative Communication Equipment — grouped in MDC 23, the procedure side of this code's crossing.” · check together
  • F003GPZ — Communicative/Cognitive Integration Skills Assessment of Neurological System - Whole Body using Computer [Same-MDC procedure]: “Communicative/Cognitive Integration Skills Assessment of Neurological System - Whole Body using Computer — grouped in MDC 23, the procedure side of this code's crossing.” · check together
  • F003GYZ — Communicative/Cognitive Integration Skills Assessment of Neurological System - Whole Body using Other Equipment [Same-MDC procedure]: “Communicative/Cognitive Integration Skills Assessment of Neurological System - Whole Body using Other Equipment — grouped in MDC 23, the procedure side of this code's crossing.” · check together
  • F003GZZ — Communicative/Cognitive Integration Skills Assessment of Neurological System - Whole Body [Same-MDC procedure]: “Communicative/Cognitive Integration Skills Assessment of Neurological System - Whole Body — grouped in MDC 23, the procedure side of this code's crossing.” · check together
  • and 1230 more

Drugs & chemicals

  • Alfentanil — Alfentanil — Underdosing [Drug table]: “Alfentanil (Underdosing)”
  • Fentanyl (analogs) — Fentanyl (analogs) — Underdosing [Drug table]: “Fentanyl (analogs) (Underdosing)”
  • Sufentanil — Sufentanil — Underdosing [Drug table]: “Sufentanil (Underdosing)”

Nearest codes (40)

  • T40 — Poisoning by, adverse effect of and underdosing of narcotics and psychodysleptics [hallucinogens] [Sibling]
  • T40.411D — Poisoning by fentanyl or fentanyl analogs, accidental (unintentional), subsequent encounter [Sibling]
  • T40.411S — Poisoning by fentanyl or fentanyl analogs, accidental (unintentional), sequela [Sibling]
  • T40.412 — Poisoning by fentanyl or fentanyl analogs, intentional self-harm [Sibling]
  • T40.412A — Poisoning by fentanyl or fentanyl analogs, intentional self-harm, initial encounter [Sibling]
  • T40.412D — Poisoning by fentanyl or fentanyl analogs, intentional self-harm, subsequent encounter [Sibling]
  • T40.412S — Poisoning by fentanyl or fentanyl analogs, intentional self-harm, sequela [Sibling]
  • T40.413 — Poisoning by fentanyl or fentanyl analogs, assault [Sibling]
  • and 32 more

Change history

  • FY2021 — Added to the code set [Change history]

Frequently Asked Questions (FAQ) & Clinical Guidance

Does T40.416D require a 7th character?

Yes. The appropriate 7th character is to be added to each code from category T40.

Nearest Codes in This Family

Official ICD-10-CM classifications closest to T40.416D in its code family, with their registry titles.

  • T40.415A — Adverse effect of fentanyl or fentanyl analogs, initial encounter
  • T40.415D — Adverse effect of fentanyl or fentanyl analogs, subsequent encounter
  • T40.415S — Adverse effect of fentanyl or fentanyl analogs, sequela
  • T40.416 — Underdosing of fentanyl or fentanyl analogs
  • T40.416A — Underdosing of fentanyl or fentanyl analogs, initial encounter
  • T40.416S — Underdosing of fentanyl or fentanyl analogs, sequela
  • T40.42 — Poisoning by, adverse effect of and underdosing of tramadol
  • T40.421 — Poisoning by tramadol, accidental (unintentional)
  • T40.421A — Poisoning by tramadol, accidental (unintentional), initial encounter
  • T40.421D — Poisoning by tramadol, accidental (unintentional), subsequent encounter

View all codes in the T40 family