2026 ICD-10-CM Diagnosis Code T54.3X1AToxic effect of corrosive alkalis and alkali-like substances, accidental (unintentional), initial encounter
T54.3X1A is a billable ICD-10-CM diagnosis code for toxic effect of corrosive alkalis and alkali-like substances, 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 lye
- Accidental poisoning by caustic alkalis
- Accidental poisoning by lye
- Accidental poisoning by sodium hydroxide
- Alkali burn of skin
- Alkaline chemical burn of conjunctival sac
- Alkaline chemical burn of cornea
- Alkaline chemical burn of cornea and conjunctival sac
- Alkaline chemical burn of cornea AND/OR conjunctival sac
- Burn of conjunctival sac
- Burn of cornea and conjunctival sac
- Burn of esophagus
- Burning caused by ammonia
- Burning caused by caustic alkali
- Burning caused by caustic oven cleaner
- Burning caused by cement
- Burning caused by lime
- Chemical burn injury to conjunctiva
- Chemical burn of esophagus
- Chemical burn of face
- Chemical burn of gastrointestinal tract
- Chemical burn of internal organ
- Chemical injury to cornea
- Corrosion of esophagus
- Esophageal injury caused by alkali
- Lye causing toxic effect
- Toxic effect of caustic alkali
- Toxic effect of potassium hydroxide
- Toxic effect of sodium hydroxide
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.
Clinical InformationClinical
Burn of Esophagus
thermal or caustic injury to the esophagus.
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 |
|---|---|---|---|---|---|---|
| Alkali (caustic) | T54.3X1 | T54.3X2 | T54.3X3 | T54.3X4 | – | – |
| Chloride of lime (bleach) | T54.3X1 | T54.3X2 | T54.3X3 | T54.3X4 | – | – |
| Drano (drain cleaner) | T54.3X1 | T54.3X2 | T54.3X3 | T54.3X4 | – | – |
| Hydroxide, caustic | T54.3X1 | T54.3X2 | T54.3X3 | T54.3X4 | – | – |
| Lime (chloride) | T54.3X1 | T54.3X2 | T54.3X3 | T54.3X4 | – | – |
| Lye (concentrated) | T54.3X1 | T54.3X2 | T54.3X3 | T54.3X4 | – | – |
| Potash (caustic) | T54.3X1 | T54.3X2 | T54.3X3 | T54.3X4 | – | – |
| Quicklime | T54.3X1 | T54.3X2 | T54.3X3 | T54.3X4 | – | – |
| Soda (caustic) | T54.3X1 | T54.3X2 | T54.3X3 | T54.3X4 | – | – |
| Soda (caustic)::bicarb | T54.3X1 | T54.3X2 | T54.3X3 | T54.3X4 | – | – |
| Soda (caustic)::chlorinated | T54.3X1 | T54.3X2 | T54.3X3 | T54.3X4 | – | – |
| Triethanolamine NEC | T54.3X1 | T54.3X2 | T54.3X3 | T54.3X4 | – | – |
| Triethanolamine NEC::detergent | T54.3X1 | T54.3X2 | T54.3X3 | T54.3X4 | – | – |
| Triethanolamine NEC::trinitrate (biphosphate) | T54.3X1 | T54.3X2 | T54.3X3 | T54.3X4 | – | – |
Convert T54.3X1A to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About T54.3X1AOverview
Is T54.3X1A a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report toxic effect of corrosive alkalis and alkali-like substances, accidental (unintentional), initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character A in T54.3X1A mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for toxic effect of corrosive alkalis and alkali-like substances, accidental (unintentional), such as an emergency visit or first evaluation.
What MS-DRG does T54.3X1A group to?
When toxic effect of corrosive alkalis and alkali-like substances, 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 T54.3X1A?
Under the General Equivalence Mappings, toxic effect of corrosive alkalis and alkali-like substances, accidental (unintentional), initial encounter converts to ICD-9-CM 983.2 (toxic eff caustic alkali) 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.
