2026 ICD-10-CM Diagnosis Code T53.5X4SToxic effect of chlorofluorocarbons, undetermined, sequela
T53.5X4S is a billable ICD-10-CM diagnosis code for toxic effect of chlorofluorocarbons, undetermined, sequela. The 7th character S marks it as a sequela code, which reports a problem that remains after the original condition has resolved. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 922 through 923. The code is exempt from POA reporting. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Poisoning/toxic effect/adverse effects/underdosing, sequela.
Code Identity
Code Classification
Present on Admission (POA)Billing
T53.5X4S is exempt from POA reporting on inpatient claims to general acute care hospitals. Review other POA exempt codes.
Coding GuidelinesGuidance
The appropriate 7th character is to be added to each code from block Toxic effect of halogen derivatives of aliphatic and aromatic hydrocarbons (T53). 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
Chlorofluorocarbons
a series of hydrocarbons containing both chlorine and fluorine. these have been used as refrigerants, blowing agents, cleaning fluids, solvents, and as fire extinguishing agents. they have been shown to cause stratospheric ozone depletion and have been banned for many uses.Chlorofluorocarbons, Ethane
a group of ethane-based halogenated hydrocarbons containing one or more fluorine and chlorine atoms.Chlorofluorocarbons, Methane
a group of methane-based halogenated hydrocarbons containing one or more fluorine and chlorine atoms.
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 |
|---|---|---|---|---|---|---|
| Chlorofluorocarbons | T53.5X1 | T53.5X2 | T53.5X3 | T53.5X4 | – | – |
| Dichlorodifluoromethane | T53.5X1 | T53.5X2 | T53.5X3 | T53.5X4 | – | – |
| Freon | T53.5X1 | T53.5X2 | T53.5X3 | T53.5X4 | – | – |
| Refrigerant gas (chlorofluoro-carbon) | T53.5X1 | T53.5X2 | T53.5X3 | T53.5X4 | – | – |
| Refrigerant gas (chlorofluoro-carbon)::not chlorofluoro-carbon | T53.5X1 | T53.5X2 | T53.5X3 | T53.5X4 | – | – |
| Trichlorofluoromethane NEC | T53.5X1 | T53.5X2 | T53.5X3 | T53.5X4 | – | – |
Convert T53.5X4S to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About T53.5X4SOverview
Is T53.5X4S (Toxic effect of chlorofluorocarbons, undetermined) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report toxic effect of chlorofluorocarbons, undetermined, sequela on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character S in T53.5X4S mean?
The final character S makes this a sequela code: it reports a lingering problem that remains after the toxic effect of chlorofluorocarbons, undetermined itself has resolved, not the original event.
What MS-DRG does T53.5X4S group to?
When toxic effect of chlorofluorocarbons, undetermined, sequela is the principal diagnosis on an inpatient stay, it groups to MS-DRG 922, 923, with relative weights from 1.0177 to 1.7494 depending on complications. Higher weights mean higher Medicare reimbursement.
Is T53.5X4S exempt from POA reporting?
Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for toxic effect of chlorofluorocarbons, undetermined, sequela on inpatient claims.
What is the ICD-9 equivalent of T53.5X4S?
Under the General Equivalence Mappings, toxic effect of chlorofluorocarbons, undetermined, sequela converts to ICD-9-CM 909.1 (late eff nonmed substanc). 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.
