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T50 vs Y63.4

T50 (Poisoning by, adverse effect of and underdosing of diuretics and other and unspecified drugs, medicaments and biological substances) compared with Y63.4 (Failure in dosage in electroshock or insulin-shock therapy), from the official CMS tabular data.

Summary

These codes can be reported together when both conditions are documented, because Y63.4 lists T50 under Excludes2, which marks them as distinct conditions.

Official rule
What is different?

The conditions named, billing status and chapter.T50 is “Poisoning by, adverse effect of and underdosing of diuretics and other and unspecified drugs, medicaments and biological substances”; Y63.4 is “Failure in dosage in electroshock or insulin-shock therapy”. T50 is a non-billable header; Y63.4 is billable. T50 sits in S00-T88 — Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88); Y63.4 in V00-Y99 — External Causes of Morbidity (V00-Y99).

Registry fact

Can these codes be reported together?

Yes, when both are documented.Y63.4 lists T50 under Excludes2: “accidental overdose of drug or wrong drug given in error (T36-T50)”. Excludes2 marks distinct conditions that may both be reported when both are documented.

Official ruleGuide: Excludes1 vs Excludes2

Is there an Excludes1 relationship?

None.Neither entry carries an Excludes1 note that names the other code. T50 carries 1 Excludes1 note and Y63.4 carries 1 Excludes1 note covering other codes; the side-by-side table quotes them.

Official rule

Is there an Excludes2 relationship?

Yes.Y63.4’s tabular entry: “accidental overdose of drug or wrong drug given in error (T36-T50)”. The note covers T50.

Official ruleGuide: Excludes1 vs Excludes2

Is one more specific?

Not comparable.The codes sit in different categories; specificity is only comparable within one category.

Is one a parent or header code?

One is a header.T50 is a non-billable header, but Y63.4 is not one of its subdivisions.

Registry fact

Are there sequencing instructions?

None.Neither entry carries a Code First or Use Additional Code note that names the other.

Official rule

Are there other coding relationships?

None found.No laterality, encounter-phase, Table of Neoplasms, Table of Drugs and Chemicals, or history-versus-active-disease relationship links these codes.

MedCoder-derived

Official rule: a tabular instructional note or a section of the ICD-10-CM Official Guidelines, quoted as published. Registry fact: the codes’ own published attributes (titles, billable status, position in the hierarchy, code set). MedCoder-derived: a reading MedCoder computes from those facts; it is not itself a rule. How to read the labels

Can these codes be reported together?

Informational

Excludes2 relationship

Y63.4
Failure in dosage in electroshock or insulin-shock therapy
↔
T50
Poisoning by, adverse effect of and underdosing of diuretics and other and unspecified drugs, medicaments and biological substances

What we found

Yes, when both are documented.Y63.4 carries an Excludes2 note covering T50: “accidental overdose of drug or wrong drug given in error (T36-T50)”

Excludes2 marks distinct conditions — both may be reported when both are documented.

What to review

Report both only when the documentation supports both conditions; otherwise report the one documented.

Guide: Excludes1 vs Excludes2Check these on a claim

Why it matters

An Excludes2 note means the excluded condition is not part of the code above it, but a patient can have both. Report both when both are documented.

Source / rule

CMS ICD-10-CM tabular instructional notes

Official guidance behind these answers

  • Section I.A.12.b — Excludes2 · applies to: Excludes2

    A type 2 Excludes note represents “Not included here.” An excludes2 note indicates that the condition excluded is not part of the condition represented by the code, but a patient may have both conditions at the same time. When an Excludes2 note appears under a code, it is acceptable to use both the code and the excluded code together, when appropriate.

    ICD-10-CM Official Guidelines FY2026

Quoted from the ICD-10-CM Official Guidelines for Coding and Reporting in effect for the release shown. The tabular notes above are the code-level instruction; these sections are the convention that says how such a note is applied. Source document (CMS PDF) · Release and checksum

Side by side

T50Poisoning by, adverse effect of and underdosing of diuretics and other and unspecified drugs, medicaments and biological substancesY63.4Failure in dosage in electroshock or insulin-shock therapy
Billing statusNon-billable header

Report instead: T50.0X1A, T50.0X1D, T50.0X1S, T50.0X2A, T50.0X2D

Billable
ClassificationS00-T88 — Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88)V00-Y99 — External Causes of Morbidity (V00-Y99)
DefinitionPoisoning by, adverse effect of and underdosing of diuretics and other and unspecified drugs, medicaments and biological substances is a non-billable ICD-10-CM category code (T50).Failure in dosage in electroshock or insulin-shock therapy is a billable ICD-10-CM diagnosis code (Y63.4).
7th characterThe appropriate 7th character is to be added to each code from category T50—
Includes
adverse effect of correct substance properly administered
poisoning by overdose of substance
poisoning by wrong substance given or taken in error
underdosing by (inadvertently) (deliberately) taking less substance than prescribed or instructed
—
Excludes1
toxic reaction to local anesthesia in pregnancy (O29.3-)
surgical and medical procedures as the cause of abnormal reaction of the patient, without mention of misadventure at the time of the procedure (Y83-Y84)
Excludes2
abuse and dependence of psychoactive substances (F10-F19)
abuse of non-dependence-producing substances (F55.-)
immunodeficiency due to drugs (D84.821)
drug reaction and poisoning affecting newborn (P00-P96)
pathological drug intoxication (inebriation) (F10-F19)
accidental overdose of drug or wrong drug given in error (T36-T50)
breakdown or malfunctioning of medical device (during procedure) (after implantation) (ongoing use) (Y70-Y82)
Code first
, for adverse effects, the nature of the adverse effect, such as:
adverse effect NOS (T88.7)
—
Use additional code
code(s) to specify:
manifestations of poisoning
underdosing or failure in dosage during medical and surgical care (Y63.6, Y63.8-Y63.9)
—

Notes are the code’s own tabular entry, quoted as published. A note that names the other code is the one the verdict above rests on.

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Derived from the official CMS ICD-10-CM tabular data (FY2027). A coding-rule comparison, not billing advice: payer-specific edits and medical-necessity policy are outside its scope. All data sources