2026 ICD-10-CM Diagnosis Code T46.1X5SAdverse effect of calcium-channel blockers, sequela
T46.1X5S is a billable ICD-10-CM diagnosis code for adverse effect of calcium-channel blockers, 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 not accepted as a principal diagnosis by the Medicare Code Editor and 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
Code EditsBilling
Medicare Code Editor checks that affect claim validity for T46.1X5S.
Present on Admission (POA)Billing
T46.1X5S 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.
- Amlodipine adverse reaction
- Calcium-channel blocker adverse reaction
- Class IV antiarrhythmic adverse reaction
- Diltiazem adverse reaction
- Felodipine adverse reaction
- Isradipine adverse reaction
- Lidoflazine adverse reaction
- Nicardipine adverse reaction
- Nifedipine adverse reaction
- Nimodipine adverse reaction
- Verapamil adverse reaction
Coding GuidelinesGuidance
When coding an adverse effect of a drug that has been correctly prescribed and properly administered, assign the appropriate code for the nature of the adverse effect followed by the appropriate code for the adverse effect of the drug.
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
Bepridil
a long-acting calcium-blocking agent with significant anti-anginal activity. the drug produces significant coronary vasodilation and modest peripheral effects. it has antihypertensive and selective anti-arrhythmia activities and acts as a calmodulin antagonist.Diltiazem
a benzothiazepine derivative with vasodilating action due to its antagonism of the actions of calcium ion on membrane functions.Felodipine
a dihydropyridine calcium antagonist with positive inotropic effects. it lowers blood pressure by reducing peripheral vascular resistance through a highly selective action on smooth muscle in arteriolar resistance vessels.Fendiline
coronary vasodilator; inhibits calcium function in muscle cells in excitation-contraction coupling; proposed as antiarrhythmic and antianginal agents.Gallopamil
coronary vasodilator that is an analog of iproveratril (verapamil) with one more methoxy group on the benzene ring.Isradipine
a potent antagonist of calcium channels that is highly selective for vascular smooth muscle. it is effective in the treatment of chronic stable angina pectoris, hypertension, and congestive cardiac failure.Lidoflazine
coronary vasodilator with some antiarrhythmic action.Nicardipine
a potent calcium channel blockader with marked vasodilator action. it has antihypertensive properties and is effective in the treatment of angina and coronary spasms without showing cardiodepressant effects. it has also been used in the treatment of asthma and enhances the action of specific antineoplastic agents.Nifedipine
a potent vasodilator agent with calcium antagonistic action. it is a useful anti-anginal agent that also lowers blood pressure.Nimodipine
a calcium channel blockader with preferential cerebrovascular activity. it has marked cerebrovascular dilating effects and lowers blood pressure.Nisoldipine
a dihydropyridine calcium channel antagonist that acts as a potent arterial vasodilator and antihypertensive agent. it is also effective in patients with cardiac failure and angina.Nitrendipine
a calcium channel blocker with marked vasodilator action. it is an effective antihypertensive agent and differs from other calcium channel blockers in that it does not reduce glomerular filtration rate and is mildly natriuretic, rather than sodium retentive.Verapamil
a calcium channel blocker that is a class iv anti-arrhythmia agent.
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
Drug Reactions
Most of the time, medicines make our lives better. They reduce aches and pains, fight infections, and control problems such as high blood pressure or diabetes. But medicines can also cause unwanted reactions, such as drug interactions, side effects, and allergies.
The full article covers:
- What is a drug interaction?
- What are side effects?
- What are drug allergies?
- How can I stay safe when taking medicines?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert T46.1X5S to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About T46.1X5SOverview
Is T46.1X5S (Adverse effect of calcium-channel blockers) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report adverse effect of calcium-channel blockers, sequela on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character S in T46.1X5S mean?
The final character S makes this a sequela code: it reports a lingering problem that remains after the adverse effect of calcium-channel blockers itself has resolved, not the original event.
What MS-DRG does T46.1X5S group to?
On inpatient claims, adverse effect of calcium-channel blockers, sequela maps to MS-DRG 922, 923, with relative weights from 1.0177 to 1.7494 depending on complications. Higher weights mean higher Medicare reimbursement.
Can T46.1X5S be a principal diagnosis?
No. The Medicare Code Editor rejects this code as a principal diagnosis because adverse effect of calcium-channel blockers, sequela describes a circumstance that influences health status rather than a current illness. Report it as a secondary diagnosis.
Is T46.1X5S 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 adverse effect of calcium-channel blockers, sequela on inpatient claims.
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.
