2026 ICD-10-CM Diagnosis Code T54.91XAToxic effect of unspecified corrosive substance, accidental (unintentional), initial encounter
T54.91XA is a billable ICD-10-CM diagnosis code for toxic effect of unspecified corrosive substance, 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. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under External cause codes: fire/burn; initial encounter; External cause codes: intent of injury, accidental/unintentional; and Toxic effects, initial encounter.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Accidental burning caused by caustic and corrosive substance
- Accidental poisoning by corrosive
- Alkali burn of skin
- Bleach burn of skin
- Bleach causing toxic effect
- Borate toxicity
- Borax toxicity
- Burn of forehead
- Burning caused by caustic and corrosive substance
- Chemical burn of internal organ
- Chemical burn of skin caused by corrosive substance
- Corrosion of third degree of shoulder and upper limb, except wrist and hand
- Corrosive gastritis
- Corrosive stricture of esophagus
- Epidermal burn of forehead
- Ingestion of corrosive chemical
- Occupational injury
- Occupational injury of skin caused by corrosive substance
- Poisoning caused by corrosive chemical
- Stricture of esophagus
- Superficial corrosion of forehead
- Superficial injury of skin of forehead
Coding GuidelinesGuidance
The appropriate 7th character is to be added to each code from block Toxic effect of corrosive substances (T54). 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
Substances in the Table of Drugs and Chemicals that reference this code family. Always confirm in the Tabular List before coding.
| Substance | Accidental | Self-harm | Assault | Undetermined | Adverse Effect | Underdosing |
|---|---|---|---|---|---|---|
| Bleach | T54.91 | T54.92 | T54.93 | T54.94 | – | – |
| Borax (cleanser) | T54.91 | T54.92 | T54.93 | T54.94 | – | – |
| Caustic (s) NEC | T54.91 | T54.92 | T54.93 | T54.94 | – | – |
| Caustic (s) NEC::alkali | T54.91 | T54.92 | T54.93 | T54.94 | – | – |
| Caustic (s) NEC::hydroxide | T54.91 | T54.92 | T54.93 | T54.94 | – | – |
| Caustic (s) NEC::potash | T54.91 | T54.92 | T54.93 | T54.94 | – | – |
| Caustic (s) NEC::soda | T54.91 | T54.92 | T54.93 | T54.94 | – | – |
| Caustic (s) NEC::specified NEC | T54.91 | T54.92 | T54.93 | T54.94 | – | – |
| Clorox (bleach) | T54.91 | T54.92 | T54.93 | T54.94 | – | – |
| Corrosive NEC | T54.91 | T54.92 | T54.93 | T54.94 | – | – |
| Corrosive NEC::acid NEC | T54.91 | T54.92 | T54.93 | T54.94 | – | – |
| Corrosive NEC::aromatics | T54.91 | T54.92 | T54.93 | T54.94 | – | – |
| Corrosive NEC::aromatics::disinfectant | T54.91 | T54.92 | T54.93 | T54.94 | – | – |
| Corrosive NEC::fumes NEC | T54.91 | T54.92 | T54.93 | T54.94 | – | – |
| Corrosive NEC::specified NEC | T54.91 | T54.92 | T54.93 | T54.94 | – | – |
| Corrosive NEC::sublimate | T54.91 | T54.92 | T54.93 | T54.94 | – | – |
| Oxidizing agent NEC | T54.91 | T54.92 | T54.93 | T54.94 | – | – |
| Purex (bleach) | T54.91 | T54.92 | T54.93 | T54.94 | – | – |
Convert T54.91XA to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About T54.91XAOverview
Is T54.91XA a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report toxic effect of unspecified corrosive substance, accidental (unintentional), initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character A in T54.91XA mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for toxic effect of unspecified corrosive substance, accidental (unintentional), such as an emergency visit or first evaluation.
What MS-DRG does T54.91XA group to?
When toxic effect of unspecified corrosive substance, 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 T54.91XA?
Under the General Equivalence Mappings, toxic effect of unspecified corrosive substance, accidental (unintentional), initial encounter converts to ICD-9-CM 983.9 (toxic effect caustic NOS) and E924.1 (accid-caustic substance). 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.
