2026 ICD-10-CM Diagnosis Code T65.94XSToxic effect of unspecified substance, undetermined, sequela
T65.94XS is a billable ICD-10-CM diagnosis code for toxic effect of unspecified substance, 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
T65.94XS is exempt from POA reporting on inpatient claims to general acute care hospitals. Review other POA exempt codes.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Acneiform eruption
- Acneiform eruption caused by chemical
- Chemical-induced pulmonary edema
- Inflammation of spinal cord caused by toxin
- Pulmonary aspiration
- Systemic sclerosis caused by chemical
- Toxic myopathy
- Toxic neuromuscular junction disorder
- Toxic polyneuropathy
- Toxic pulmonary edema
Coding GuidelinesGuidance
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 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
Toxic Polyneuropathy
polyneuropathy that is caused by exposure to toxins.Chronic Toxic Polyneuropathy
neuropathy affecting multiple nerves that is caused by prolonged exposure to toxic substances.
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 |
|---|---|---|---|---|---|---|
| Aerosol spray NEC | T65.91 | T65.92 | T65.93 | T65.94 | – | – |
| Agricultural agent NEC | T65.91 | T65.92 | T65.93 | T65.94 | – | – |
| Air contaminant (s), source/type NOS | T65.91 | T65.92 | T65.93 | T65.94 | – | – |
| Antifreeze | T65.91 | T65.92 | T65.93 | T65.94 | – | – |
| Antifreeze::alcohol | T65.91 | T65.92 | T65.93 | T65.94 | – | – |
| Antifreeze::ethylene glycol | T65.91 | T65.92 | T65.93 | T65.94 | – | – |
| Chemical substance NEC | T65.91 | T65.92 | T65.93 | T65.94 | – | – |
| Horticulture agent NEC | T65.91 | T65.92 | T65.93 | T65.94 | – | – |
| Horticulture agent NEC::with pesticide | T65.91 | T65.92 | T65.93 | T65.94 | – | – |
| Ingested substance NEC | T65.91 | T65.92 | T65.93 | T65.94 | – | – |
| Poison NEC | T65.91 | T65.92 | T65.93 | T65.94 | – | – |
| Solid substance | T65.91 | T65.92 | T65.93 | T65.94 | – | – |
| Solid substance::specified NEC | T65.91 | T65.92 | T65.93 | T65.94 | – | – |
| Spray (aerosol) | T65.91 | T65.92 | T65.93 | T65.94 | – | – |
| Spray (aerosol)::cosmetic | T65.91 | T65.92 | T65.93 | T65.94 | – | – |
| Spray (aerosol)::medicinal NEC | T65.91 | T65.92 | T65.93 | T65.94 | – | – |
| Spray (aerosol)::pesticides | T65.91 | T65.92 | T65.93 | T65.94 | – | – |
| Spray (aerosol)::specified content | T65.91 | T65.92 | T65.93 | T65.94 | – | – |
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 T65.94XS to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About T65.94XSOverview
Is T65.94XS (Toxic effect of unspecified substance, undetermined) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report toxic effect of unspecified substance, undetermined, sequela on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character S in T65.94XS mean?
The final character S makes this a sequela code: it reports a lingering problem that remains after the toxic effect of unspecified substance, undetermined itself has resolved, not the original event.
What MS-DRG does T65.94XS group to?
When toxic effect of unspecified substance, 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 T65.94XS 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 unspecified substance, undetermined, sequela on inpatient claims.
What is the ICD-9 equivalent of T65.94XS?
Under the General Equivalence Mappings, toxic effect of unspecified substance, undetermined, sequela converts to ICD-9-CM 909.1 (late eff nonmed substanc) and E989 (late eff inj-undet circ). 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.
