2026 ICD-10-CM Diagnosis Code T46.4X4SPoisoning by angiotensin-converting-enzyme inhibitors, undetermined, sequela
T46.4X4S is a billable ICD-10-CM diagnosis code for poisoning by angiotensin-converting-enzyme inhibitors, 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
T46.4X4S is exempt from POA reporting on inpatient claims to general acute care hospitals. Review other POA exempt codes.
Coding GuidelinesGuidance
When coding a poisoning or reaction to the improper use of a medication (e.g., overdose, wrong substance given or taken in error, wrong route of administration), first assign the appropriate code from categories T36-T50. The poisoning codes have an associated intent as their 5th or 6th character (accidental, intentional self-harm, assault and undetermined). If the intent of the poisoning is unknown or unspecified, code the intent as accidental intent. The undetermined intent is only for use if the documentation in the record specifies that the intent cannot be determined. Use additional code(s) for all manifestations of poisonings.
The appropriate 7th character is to be added to each code from block Poisoning by, adverse effect of and underdosing of agents primarily affecting the cardiovascular system (T46). 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
Captopril
a potent and specific inhibitor of peptidyl-dipeptidase a. it blocks the conversion of angiotensin i to angiotensin ii, a vasoconstrictor and important regulator of arterial blood pressure. captopril acts to suppress the renin-angiotensin system and inhibits pressure responses to exogenous angiotensin.Cilazapril
one of the angiotensin-converting enzyme inhibitors (ace inhibitors) used for hypertension. it is a prodrug that is hydrolyzed after absorption to its main metabolite cilazaprilat.Enalapril
an angiotensin-converting enzyme inhibitor that is used to treat hypertension and heart failure.Enalaprilat
the active metabolite of enalapril and one of the potent, intravenously administered, angiotensin-converting enzyme inhibitors. it is an effective agent for the treatment of essential hypertension and has beneficial hemodynamic effects in heart failure. the drug produces renal vasodilation with an increase in sodium excretion.Fosinopril
a phosphinic acid-containing angiotensin-converting enzyme inhibitor that is effective in the treatment of hypertension. it is a prodrug that is converted to its active metabolite fosinoprilat.Lisinopril
one of the angiotensin-converting enzyme inhibitors (ace inhibitors), orally active, that has been used in the treatment of hypertension and congestive heart failure.Perindopril
an angiotensin-converting enzyme inhibitor. it is used in patients with hypertension and heart failure.Quinapril
a tetrahydroisoquinoline derivative and angiotensin converting enzyme inhibitor that is used in the treatment of hypertension and heart failure.Ramipril
a long-acting angiotensin-converting enzyme inhibitor. it is a prodrug that is transformed in the liver to its active metabolite ramiprilat.
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.
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 T46.4X4S to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About T46.4X4SOverview
Is T46.4X4S a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report poisoning by angiotensin-converting-enzyme inhibitors, undetermined, sequela on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character S in T46.4X4S mean?
The final character S makes this a sequela code: it reports a lingering problem that remains after the poisoning by angiotensin-converting-enzyme inhibitors, undetermined itself has resolved, not the original event.
What MS-DRG does T46.4X4S group to?
When poisoning by angiotensin-converting-enzyme inhibitors, 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 T46.4X4S 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 poisoning by angiotensin-converting-enzyme inhibitors, undetermined, sequela on inpatient claims.
What is the ICD-9 equivalent of T46.4X4S?
Under the General Equivalence Mappings, poisoning by angiotensin-converting-enzyme inhibitors, undetermined, sequela converts to ICD-9-CM 909.0 (late eff drug poisoning) 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.
