T65.85 ICD-10-CM Code: Toxic effect of medetomidine
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
Official Tabular Instructional Notes
Sequencing, inclusion, and exclusion notes published for T65.85 in the official ICD-10-CM tabular list.
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).
- contact with and (suspected) exposure to toxic substances (Z77.-) Compare T65.85 vs Z77 →
Use Additional Code
Supplementary codes the tabular list directs you to add.
- Use additional code to identify associated manifestations, such as:
- bradycardia NOS (R00.1)
- somnolence, stupor and coma (R40.-)
- 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 — 2026-10-01Added to the code setToxic effect of medetomidineFY2027 changes
Verify Before Coding
- Not billable as written — a more specific code is required: T65.851A, T65.851D, T65.851S, T65.852A, T65.852D.
- Requires a 7th character. "The appropriate 7th character is to be added to each code from category T65" Options: T65.851A, T65.851D, T65.851S, T65.852A, T65.852D, T65.852S
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 T65.85 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]
Use Additional Code
- R00.1 — Bradycardia, unspecified [Use Additional Code]: “bradycardia NOS (R00.1)” · check together
- R40 — Somnolence, stupor and coma [Use Additional Code]: “somnolence, stupor and coma (R40.-)” · check together
Nearest codes (40)
- T65 — Toxic effect of other and unspecified substances [Sibling]
- T65.834A — Toxic effect of fiberglass, undetermined, initial encounter [Sibling]
- T65.834D — Toxic effect of fiberglass, undetermined, subsequent encounter [Sibling]
- T65.834S — Toxic effect of fiberglass, undetermined, sequela [Sibling]
- T65.84 — Toxic effect of xylazine [Sibling]
- T65.841 — Toxic effect of xylazine, accidental (unintentional) [Sibling]
- T65.841A — Toxic effect of xylazine, accidental (unintentional), initial encounter [Sibling]
- T65.841D — Toxic effect of xylazine, accidental (unintentional), subsequent encounter [Sibling]
- and 32 more
Change history
- FY2027 — Added to the code set [Change history]
Frequently Asked Questions (FAQ) & Clinical Guidance
Can T65.85 be billed directly?
No. T65.85 (Toxic effect of medetomidine) is a non-billable ICD-10-CM category code. A more specific billable subcode must be selected based on clinical documentation.
Does T65.85 require a 7th character?
Yes. The appropriate 7th character is to be added to each code from category T65.
Nearest Codes in This Family
Official ICD-10-CM classifications closest to T65.85 in its code family, with their registry titles.
- T65.843S — Toxic effect of xylazine, assault, sequela
- T65.844 — Toxic effect of xylazine, undetermined
- T65.844A — Toxic effect of xylazine, undetermined, initial encounter
- T65.844D — Toxic effect of xylazine, undetermined, subsequent encounter
- T65.844S — Toxic effect of xylazine, undetermined, sequela
- T65.851 — Toxic effect of medetomidine, accidental (unintentional)
- T65.851A — Toxic effect of medetomidine, accidental (unintentional), initial encounter
- T65.851D — Toxic effect of medetomidine, accidental (unintentional), subsequent encounter
- T65.851S — Toxic effect of medetomidine, accidental (unintentional), sequela
- T65.852 — Toxic effect of medetomidine, intentional self-harm