T52.821A: Toxic effect of cycloparaffins, accidental (unintentional), initial encounter

New code · FY2027

Billable: use this code on claims.

• New code, effective October 1, 2026 (FY2027). Before that, this condition was coded as T52.8X1A.

Code breakdown

Coding notes

Inclusion terms (from T52.821)

• Toxic effects of cycloparaffins NOS

Inclusion terms (from T52.82)

• Toxic effects of naphthenes
• Toxic effects of cycloalkanes

Excludes1 (from T52)

• halogen derivatives of aliphatic and aromatic hydrocarbons (T53.-)

7th character (from T52)

• The appropriate 7th character is to be added to each code from category T52

7th characters (category T52)

• A initial encounter
• D subsequent encounter
• S sequela

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All FY2027 ICD-10-CM changes

ICD-10-CM codes and descriptions are from the CMS and NCHS code files. Coverage is from the CMS Medicare Coverage Database billing and coding articles.