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ICD-10/T52.821

T52.821 ICD-10-CM Code: Toxic effect of cycloparaffins, accidental (unintentional)

Billing Status: NO. This is a clinician non-billable / parent hierarchy grouping in the ICD-10-CM system.

Code Set: New for FY2027 — not valid before October 1, 2026.

Official Registry Overview & Definition

No additional overview provided for this record.

Official Tabular Instructional Notes

Sequencing, inclusion, and exclusion notes published for T52.821 in the official ICD-10-CM tabular list.

Inclusion Terms

Alternative terms the tabular list files under this code.

  • Toxic effects of cycloparaffins NOS

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).

Use Additional Code

Supplementary codes the tabular list directs you to add.

  • Use additional 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.-)

Change history

  • FY2027 — 2026-10-01
    Added to the code set
    Toxic effect of cycloparaffins, accidental (unintentional)
    FY2027 changes

Verify Before Coding

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

Contextual Map

Every relationship of T52.821 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]
  • T51-T65 — Toxic effects of substances chiefly nonmedicinal as to source [Hierarchy]

Drugs & chemicals

  • Cycloalkanes — Cycloalkanes — Poisoning, Accidental (unintentional) [Drug table]: “Cycloalkanes (Poisoning, Accidental (unintentional))”
  • Cyclohexane — Cyclohexane — Poisoning, Accidental (unintentional) [Drug table]: “Cyclohexane (Poisoning, Accidental (unintentional))”
  • Cycloparaffins — Cycloparaffins — Poisoning, Accidental (unintentional) [Drug table]: “Cycloparaffins (Poisoning, Accidental (unintentional))”
  • Hexamethylene — Hexamethylene — Poisoning, Accidental (unintentional) [Drug table]: “Hexamethylene (Poisoning, Accidental (unintentional))”
  • Naphthenes — Naphthenes — Poisoning, Accidental (unintentional) [Drug table]: “Naphthenes (Poisoning, Accidental (unintentional))”

Nearest codes (40)

  • T52 — Toxic effect of organic solvents [Sibling]
  • T52.4X4S — Toxic effect of ketones, undetermined, sequela [Sibling]
  • T52.8 — Toxic effects of other organic solvents [Sibling]
  • T52.81 — Toxic effects of alkenes [Sibling]
  • T52.811 — Toxic effect of alkenes, accidental (unintentional) [Sibling]
  • T52.811A — Toxic effect of alkenes, accidental (unintentional), initial encounter [Sibling]
  • T52.811D — Toxic effect of alkenes, accidental (unintentional), subsequent encounter [Sibling]
  • T52.811S — Toxic effect of alkenes, accidental (unintentional), sequela [Sibling]
  • and 32 more

Change history

  • FY2027 — Added to the code set [Change history]

Frequently Asked Questions (FAQ) & Clinical Guidance

Can T52.821 be billed directly?

No. T52.821 (Toxic effect of cycloparaffins, accidental (unintentional)) is a non-billable ICD-10-CM category code. A more specific billable subcode must be selected based on clinical documentation.

Does T52.821 require a 7th character?

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

Nearest Codes in This Family

Official ICD-10-CM classifications closest to T52.821 in its code family, with their registry titles.

  • T52.814 — Toxic effect of alkenes, undetermined
  • T52.814A — Toxic effect of alkenes, undetermined, initial encounter
  • T52.814D — Toxic effect of alkenes, undetermined, subsequent encounter
  • T52.814S — Toxic effect of alkenes, undetermined, sequela
  • T52.82 — Toxic effects of cycloparaffins
  • T52.821A — Toxic effect of cycloparaffins, accidental (unintentional), initial encounter
  • T52.821D — Toxic effect of cycloparaffins, accidental (unintentional), subsequent encounter
  • T52.821S — Toxic effect of cycloparaffins, accidental (unintentional), sequela
  • T52.822 — Toxic effect of cycloparaffins, intentional self-harm
  • T52.822A — Toxic effect of cycloparaffins, intentional self-harm, initial encounter

View all codes in the T52 family

Associated Substances (5)

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

  • Cycloalkanes
  • Cyclohexane
  • Cycloparaffins
  • Hexamethylene
  • Naphthenes