2026 ICD-10-CM Diagnosis Code T65.844S

Clinical Information

• Xylazine

  an adrenergic alpha-2 agonist used as a sedative, analgesic and centrally acting muscle relaxant in veterinary medicine.

Coding Guidelines

The appropriate 7th character is to be added to each code from block Toxic effect of other and unspecified substances (T65). Use the following options for the aplicable episode of care:

• A - initial encounter
• D - subsequent encounter
• S - sequela

New 2026 ICD-10-CM Code

T65.844S is new to ICD-10-CM code set for the FY 2026, effective October 1, 2025. The National Center for Health Statistics (NCHS) has published an update to the ICD-10-CM diagnosis codes which became effective October 1, 2025. This is a new and revised code for the FY 2026 (October 1, 2025 - September 30, 2026).

MS-DRG Mapping for ICD-10-CM Code T65.844S

Diagnosis-Related Groups (DRGs) are used to classify hospital cases for billing and healthcare management. They help standardize how hospitals and other providers are reimbursed for inpatient care. Patients are grouped based on their principal diagnosis into broader categories called Major Diagnostic Categories (MDCs).

Once assigned to a DRG, the hospital receives a set payment for the patient’s care, regardless of the actual services provided. This fixed rate is intended to cover the typical cost of treating patients within that group. The payment amount depends on the DRG's relative weight, which reflects the expected complexity and cost of care based on the severity of the patient’s condition.

Diagnostic related groups encourage healthcare providers to focus on quality and efficiency in patient care while managing costs effectively. The diagnosis code is present in the following groups for version MS-DRG V43.0 applicable from 10/01/2025 through 09/30/2026.

Present on Admission (POA)

T65.844S is exempt from POA reporting - The Present on Admission (POA) indicator is used for diagnosis codes included in claims involving inpatient admissions to general acute care hospitals. POA indicators must be reported to CMS on each claim to facilitate the grouping of diagnoses codes into the proper Diagnostic Related Groups (DRG). CMS publishes a listing of specific diagnosis codes that are exempt from the POA reporting requirement. Review other POA exempt codes here.

CMS POA Indicator Options and Definitions

Replacement Code

T65844S replaces the following previously assigned ICD-10-CM code(s):

• T65.894S - Toxic effect of oth substances, undetermined, sequela

Table of Drugs and Chemicals

The parent code T65.844 of the current diagnosis code is referenced in the Table of Drugs and Chemicals, this table contains a classification of drugs, industrial solvents, corrosive gases, noxious plants, pesticides, and other toxic agents.

According to ICD-10-CM coding guidelines it is advised to do not code directly from the Table of Drugs and Chemicals, instead always refer back to the Tabular List when doing the initial coding. Each substance in the table is assigned a code according to the poisoning classification and external causes of adverse effects. It is important to use as many codes as necessary to specify all reported drugs, medicinal or chemical substances. If the same diagnosis code describes the causative agent for more than one adverse reaction, poisoning, toxic effect or underdosing, utilize the code only once.

Code History

• FY 2026 - Code Added, effective from 10/1/2025 through 9/30/2026