2026 ICD-10-CM Diagnosis Code T59.1X1AToxic effect of sulfur dioxide, accidental (unintentional), initial encounter
T59.1X1A is a billable ICD-10-CM diagnosis code for toxic effect of sulfur dioxide, accidental (unintentional), initial encounter. The 7th character A marks it as an initial encounter code, used while the patient is receiving active treatment. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 917 through 918. Coders also document this condition as accidental poisoning by sulfur dioxide. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under External cause codes: intent of injury, accidental/unintentional; External cause codes: poisoning by non-drug; and Toxic effects, initial encounter.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Accidental poisoning by sulfur dioxide
- Adverse reaction to food additive
- Allergic reaction caused by food additive
- Anaphylaxis caused by food additive
- Anaphylaxis caused by sulfur dioxide
- Toxic effect of sulfur dioxide
Coding GuidelinesGuidance
The appropriate 7th character is to be added to each code from block Toxic effect of other gases, fumes and vapors (T59). Use the following options for the applicable episode of care:
- A - initial encounter
- D - subsequent encounter
- S - sequela
Source: ICD-10-CM Official Guidelines for Coding and Reporting, FY 2026, published by CMS and the National Center for Health Statistics.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Table of Drugs and ChemicalsClinical
Patient EducationClinical
Poisoning
A poison is any substance that is harmful to your body. You might swallow it, inhale it, inject it, or absorb it through your skin. Any substance can be poisonous if too much is taken. Poisons can include:
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert T59.1X1A to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About T59.1X1AOverview
Is T59.1X1A (Toxic effect of sulfur dioxide, accidental (unintentional)) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report toxic effect of sulfur dioxide, accidental (unintentional), initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character A in T59.1X1A mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for toxic effect of sulfur dioxide, accidental (unintentional), such as an emergency visit or first evaluation.
What MS-DRG does T59.1X1A group to?
When toxic effect of sulfur dioxide, accidental (unintentional), initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 917, 918, with relative weights from 0.8571 to 1.5684 depending on complications. Higher weights mean higher Medicare reimbursement.
What is the ICD-9 equivalent of T59.1X1A?
Under the General Equivalence Mappings, toxic effect of sulfur dioxide, accidental (unintentional), initial encounter converts to ICD-9-CM 987.3 (toxic eff sulfur dioxide) and E869.1 (acc poisn-sulfur dioxide). The mapping is approximate, so confirm the match fits the documentation.
Footnotes
[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.
