Skip to main content

T56.1 vs T61

T56.1 (Toxic effects of mercury and its compounds) compared with T61 (Toxic effect of noxious substances eaten as seafood), from the official CMS tabular data. Do not report these codes together: the official tabular list marks them Excludes1.

Relationship

Conflict

Excludes1 conflict

T61
Toxic effect of noxious substances eaten as seafood
↔
T56.1
Toxic effects of mercury and its compounds

Not coded here — these two are mutually exclusive.

“toxic effect of mercury (T56.1-)”

An Excludes1 note means the two conditions cannot occur together, so the pair should not be reported for the same encounter. The sole exception is when the conditions are documented as unrelated to each other.

Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a

Can these codes be reported together?

No — do not report together. T61 carries an Excludes1 note covering T56.1: “toxic effect of mercury (T56.1-)”

Sole exception: when the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).

Side by side

T56.1Toxic effects of mercury and its compoundsT61Toxic effect of noxious substances eaten as seafood
Billing statusNon-billable headerNon-billable header

Report instead: T61.01XA, T61.01XD, T61.01XS, T61.02XA, T61.02XD

ClassificationS00-T88 — Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88)S00-T88 — Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88)
DefinitionToxic effects of mercury and its compounds is a non-billable ICD-10-CM category code (T56.1).Toxic effect of noxious substances eaten as seafood is a non-billable ICD-10-CM category code (T61).
7th characterThe appropriate 7th character is to be added to each code from category T56The appropriate 7th character is to be added to each code from category T61
Includes
toxic effects of fumes and vapors of metals
toxic effects of metals from all sources, except medicinal substances
—
Use additional code
code to identify any retained metal foreign body, if applicable (Z18.0-, T18.1-)
code(s):
for all associated manifestations of toxic effect, such as: respiratory conditions due to external agents (J60-J70)
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)
Edit this comparisonCheck a whole claim

Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources