2026 ICD-10-CM Diagnosis Code T46.5X4SPoisoning by other antihypertensive drugs, undetermined, sequela
T46.5X4S is a billable ICD-10-CM diagnosis code for poisoning by other antihypertensive drugs, 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
T46.5X4S 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
Bethanidine
a guanidinium antihypertensive agent that acts by blocking adrenergic transmission. the precise mode of action is not clear.Clonidine
an imidazoline sympatholytic agent that stimulates alpha-2 adrenergic receptors and central imidazoline receptors. it is commonly used in the management of hypertension.Diazoxide
a benzothiadiazine derivative that is a peripheral vasodilator used for hypertensive emergencies. it lacks diuretic effect, apparently because it lacks a sulfonamide group.Dihydralazine
1,4-dihydrazinophthalazine. an antihypertensive agent with actions and uses similar to those of hydralazine. (from martindale, the extra pharmacopoeia, 30th ed, p354)Dihydroergotamine
a 9,10alpha-dihydro derivative of ergotamine. it is used as a vasoconstrictor, specifically for the therapy of migraine disorders.Ergotamine
a vasoconstrictor found in ergot of central europe. it is a serotonin agonist that has been used as an oxytocic agent and in the treatment of migraine disorders.Ergotamines
a series of structurally-related alkaloids containing the ergotaman backbone structure.Guanabenz
an alpha-2 selective adrenergic agonist used as an antihypertensive agent.Guanethidine
an antihypertensive agent that acts by inhibiting selectively transmission in post-ganglionic adrenergic nerves. it is believed to act mainly by preventing the release of norepinephrine at nerve endings and causes depletion of norepinephrine in peripheral sympathetic nerve terminals as well as in tissues.Guanfacine
a centrally acting antihypertensive agent with specificity towards adrenergic alpha-2 receptors.Hydralazine
a direct-acting vasodilator that is used as an antihypertensive agent.Indapamide
a benzamide-sulfonamide-indole derived diuretic that functions by inhibiting sodium chloride symporters.Carbidopa
an inhibitor of dopa decarboxylase that prevents conversion of levodopa to dopamine. it is used in parkinson disease to reduce peripheral adverse effects of levodopa. it has no anti-parkinson activity by itself.Deoxyepinephrine
sympathomimetic, vasoconstrictor agent.Methyldopa
an alpha-2 adrenergic agonist that has both central and peripheral nervous system effects. its primary clinical use is as an antihypertensive agent.Methysergide
an ergot derivative that is a congener of lysergic acid diethylamide. it antagonizes the effects of serotonin in blood vessels and gastrointestinal smooth muscle, but has few of the properties of other ergot alkaloids. methysergide is used prophylactically in migraine and other vascular headaches and to antagonize serotonin in the carcinoid syndrome.Nitroprusside
a powerful vasodilator used in emergencies to lower blood pressure or to improve cardiac function. it is also an indicator for free sulfhydryl groups in proteins.Pargyline
a monoamine oxidase inhibitor with antihypertensive properties.Pinacidil
a guanidine that opens potassium channels producing direct peripheral vasodilatation of the arterioles. it reduces blood pressure and peripheral resistance and produces fluid retention. (martindale the extra pharmacopoeia, 31st ed)Saralasin
an octapeptide analog of angiotensin ii (bovine) with amino acids 1 and 8 replaced with sarcosine and alanine, respectively. it is a highly specific competitive inhibitor of angiotensin ii that is used in the diagnosis of hypertension.Teprotide
a synthetic nonapeptide (pyr-trp-pro-arg-pro-gln-ile-pro-pro) which is identical to the peptide from the venom of the snake, bothrops jararaca. it inhibits kininase ii and angiotensin i and has been proposed as an antihypertensive agent.Todralazine
an antihypertensive agent with both central and peripheral action; it has some central nervous system depressant effects.Veratrine
a voltage-gated sodium channel activator.
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 T46.5X4S to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About T46.5X4SOverview
Is T46.5X4S (Poisoning by other antihypertensive drugs, undetermined) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report poisoning by other antihypertensive drugs, undetermined, sequela on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character S in T46.5X4S mean?
The final character S makes this a sequela code: it reports a lingering problem that remains after the poisoning by other antihypertensive drugs, undetermined itself has resolved, not the original event.
What MS-DRG does T46.5X4S group to?
When poisoning by other antihypertensive drugs, 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 T46.5X4S 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 poisoning by other antihypertensive drugs, undetermined, sequela on inpatient claims.
What is the ICD-9 equivalent of T46.5X4S?
Under the General Equivalence Mappings, poisoning by other antihypertensive drugs, 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.
