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T63.4 vs T78.2

T63.4 (Toxic effect of venom of other arthropods) compared with T78.2 (Anaphylactic shock, unspecified), from the official CMS tabular data.

Current data releases:ICD-10-CM FY2027 · ICD-10-PCS FY2027 · HCPCS October 2026 · MS-DRG v44 · Medicare Code Editor v44.0 · NCCI PTP Q4 2026 · MUE Q4 2026 · NCD code lists 2026-01 · LCD export September 28, 2026 · All releases and sources

Summary

These codes can be reported together, with T63.4 sequenced before T78.2 as the tabular note instructs.

Official rule
What is different?

The conditions named.T63.4 is “Toxic effect of venom of other arthropods”; T78.2 is “Anaphylactic shock, unspecified”.

Registry fact

Can these codes be reported together?

Yes, in the order the notes give.T63.4 is listed before T78.2; the sequencing answer below quotes the instruction.

Official ruleGuide: Code First vs Use Additional Code vs Code Also

Is one a parent or header code?

Both are headers.Both are non-billable headers, and neither contains the other.

Registry fact

Are there sequencing instructions?

Yes.T63.4 first, T78.2 as an additional code: T63.4 carries a Use Additional Code instruction covering T78.2 (“code, if applicable, for anaphylactic shock (T78.2)”).

Official ruleGuide: Code First vs Use Additional Code vs Code Also

Nothing found in 3 other checks; 1 check does not apply
Is there an Excludes1 relationship?

None.Neither entry carries an Excludes1 note that names the other code. T63.4 carries 1 Excludes1 note and T78.2 carries 3 Excludes1 notes covering other codes; the side-by-side table quotes them.

Official rule

Is there an Excludes2 relationship?

None.Neither entry carries an Excludes2 note that names the other code. T63.4 carries 1 Excludes2 note and T78.2 carries 1 Excludes2 note covering other codes; the side-by-side table quotes them.

Official rule

Is one more specific?

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

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?

Yes — in the order the notes give.

No Excludes1/Excludes2 relationship exists between these codes in the official tabular list. The sequencing instruction below sets which code is listed first on the claim.

Sequencing on the claim

Sequencing

Additional-code relationship

1st
T63.4
Toxic effect of venom of other arthropods
→
then
T78.2
Anaphylactic shock, unspecified

What we found

T63.4 first, T78.2 as an additional code

T63.4 carries a Use Additional Code instruction covering T78.2: “code, if applicable, for anaphylactic shock (T78.2)”

What to review

Report T78.2 after T63.4 when the documentation supports it.

Guide: Code First vs Use Additional Code vs Code Also

Why it matters

A "Use additional code" note means a secondary code should follow this one to fully describe the condition when the documentation supports it.

Source / rule

CMS ICD-10-CM tabular instructional notes

Official guidance behind these answers

  • Section I.B.7 — Multiple coding for a single condition · applies to: Code first / Use additional code

    In addition to the etiology/manifestation convention that requires two codes to fully describe a single condition that affects multiple body systems, there are other single conditions that also require more than one code. “Use additional code” notes are found in the Tabular List at codes that are not part of an etiology/manifestation pair where a secondary code is useful to fully describe a condition. The sequencing rule is the same as the etiology/manifestation pair, “use additional code” indicates that a secondary code should be added, if known. For example, for bacterial infections that are not included in chapter 1, a secondary code from category B95, Streptococcus, Staphylococcus, and Enterococcus, as the cause of diseases classified elsewhere, or B96, Other bacterial agents as the cause of diseases classified elsewhere, may be required to identify the bacterial organism causing the infection. A “use additional code” note will normally be found at the infectious disease code, indicating a need for the organism code to be added as a secondary code. “Code first” notes are also under certain codes that are not specifically manifestation codes but may be due to an underlying cause. When there is a “code first” note and an underlying condition is present, the underlying condition should be sequenced first, if known. […]

    ICD-10-CM Official Guidelines FY2027

  • Section I.A.13 — Etiology/manifestation convention (“code first”, “use additional code” and “in diseases classified elsewhere” notes) · applies to: Etiology/manifestation convention

    Certain conditions have both an underlying etiology and multiple body system manifestations due to the underlying etiology. For such conditions, the ICD-10-CM has a coding convention that requires the underlying condition be sequenced first, if applicable, followed by the manifestation. Wherever such a combination exists, there is a “use additional code” note at the etiology code, and a “code first” note at the manifestation code. These instructional notes indicate the proper sequencing order of the codes, etiology followed by manifestation. In most cases the manifestation codes will have in the code title, “in diseases classified elsewhere.” Codes with this title are a component of the etiology/ manifestation convention. The code title indicates that it is a manifestation code. “In diseases classified elsewhere” codes are never permitted to be used as first listed or principal diagnosis codes. They must be used in conjunction with an underlying condition code and they must be listed following the underlying condition. See category F02, Dementia in other diseases classified elsewhere, for an example of this convention. There are manifestation codes that do not have “in diseases classified elsewhere” in the title. For such codes, there is a “use additional code” note at the etiology code and a “code first” note at the manifestation code, and the rules for sequencing apply. […]

    ICD-10-CM Official Guidelines FY2027

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

Similar descriptions do not make codes interchangeable. The documentation and the official instructions decide which code applies.

Official descriptionDiffers
T63.4

Toxic effect of venom of other arthropods

T78.2

Anaphylactic shock, unspecified

StatusDiffers
T63.4
Non-billable header

A header is not reported on a claim; a code beneath it is.

Report instead: T63.411A, T63.411D, T63.411S, T63.412A, T63.412D

T78.2
Non-billable header

A header is not reported on a claim; a code beneath it is.

Report instead: T78.2XXA, T78.2XXD, T78.2XXS

Excludes1Differs
T63.4
  • contact with and (suspected) exposure to toxic substances (Z77.-)
T78.2
  • anaphylactic reaction or shock due to adverse effect of correct medicinal substance properly administered (T88.6)
  • anaphylactic reaction or shock due to adverse food reaction (T78.0-)
  • anaphylactic reaction or shock due to serum (T80.5-)
Excludes2Differs
T63.4
  • ingestion of toxic animal or plant (T61.-, T62.-)
T78.2
  • complications of surgical and medical care NEC (T80-T88)
Use additional codeDiffers
T63.4
  • code, if applicable, for anaphylactic shock (T78.2)
  • code(s):
  • for all associated manifestations of toxic effect, such as: respiratory conditions due to external agents (J60-J70)
  • personal history of foreign body fully removed (Z87.821)
  • to identify any retained foreign body, if applicable (Z18.-)
T78.2

None at this code

Code alsoDiffers
T63.4

None at this code

T78.2
  • , if applicable, place of occurrence, such as:
  • highway rest stop (Y92.523)
  • school (private) (public) (state) as the place of occurrence of the external cause (Y92.21-)
  • service areas as the place of occurrence of the external cause (Y92.52-)
  • single-family non-institutional (private) house as the place of occurrence of the external cause (Y92.01-)
  • transport vehicle as the place of occurrence of the external cause (Y92.81-)
CategoryDiffers
T63.4

T63 Toxic effect of contact with venomous animals and plants

T78.2

T78 Adverse effects, not elsewhere classified

ChapterSame for both

S00-T88 — Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88)

IncludesDiffers
T63.4
  • bite or touch of venomous animal
  • pricked or stuck by thorn or leaf
T78.2
  • Allergic shock
  • Anaphylactic reaction
  • Anaphylaxis
7th characterDiffers
T63.4
  • The appropriate 7th character is to be added to each code from category T63
T78.2
  • The appropriate 7th character is to be added to each code from category T78

No Code first note at either code.

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. In a row that differs, each code’s own notes are listed under it, and the notes every code shares are listed once beneath them.

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