2026 ICD-10-CM Diagnosis Code T50.2X5SAdverse effect of carbonic-anhydrase inhibitors, benzothiadiazides and other diuretics, sequela
T50.2X5S is a billable ICD-10-CM diagnosis code for adverse effect of carbonic-anhydrase inhibitors, benzothiadiazides and other diuretics, 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 T50.2X5S.
Present on Admission (POA)Billing
T50.2X5S 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.
- Acetazolamide adverse reaction
- Adverse reaction to chlormerodrin
- Adverse reaction to mercaptomerin
- Adverse reaction to mercurophylline
- Adverse reaction to purine derivative diuretic
- Adverse reaction to saluretic agent
- Amiloride adverse reaction
- Bendroflumethiazide adverse reaction
- Carbonic anhydrase inhibitor adverse reaction
- Chlorothiazide adverse reaction
- Chlorthalidone adverse reaction
- Cyclopenthiazide adverse reaction
- Dichlorphenamide adverse reaction
- Diuretic adverse reaction
- Hydrochlorothiazide adverse reaction
- Hydroflumethiazide adverse reaction
- Hypercalcemia caused by thiazide and/or retinol
- Mefruside adverse reaction
- Mercurial diuretic adverse reaction
- Mersalyl adverse reaction
- Methyclothiazide adverse reaction
- Metolazone adverse reaction
- Osmotic diuretic adverse reaction
- Polythiazide adverse reaction
- Potassium sparing diuretic adverse reaction
- Sulfonamide diuretic adverse reaction
- Thiazide diuretic adverse reaction
- Triamterene adverse reaction
- Xipamide 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 diuretics and other and unspecified drugs, medicaments and biological substances (T50). 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
Acetazolamide
one of the carbonic anhydrase inhibitors that is sometimes effective against absence seizures. it is sometimes useful also as an adjunct in the treatment of tonic-clonic, myoclonic, and atonic seizures, particularly in women whose seizures occur or are exacerbated at specific times in the menstrual cycle. however, its usefulness is transient often because of rapid development of tolerance. its antiepileptic effect may be due to its inhibitory effect on brain carbonic anhydrase, which leads to an increased transneuronal chloride gradient, increased chloride current, and increased inhibition. (from smith and reynard, textbook of pharmacology, 1991, p337)Amiloride
a pyrazine compound inhibiting sodium reabsorption through sodium channels in renal epithelial cells. this inhibition creates a negative potential in the luminal membranes of principal cells, located in the distal convoluted tubule and collecting duct. negative potential reduces secretion of potassium and hydrogen ions. amiloride is used in conjunction with diuretics to spare potassium loss. (from gilman et al., goodman and gilman's the pharmacological basis of therapeutics, 9th ed, p705)Bendroflumethiazide
a thiazide diuretic with actions and uses similar to those of hydrochlorothiazide. it has been used in the treatment of familial hyperkalemia, hypertension, edema, and urinary tract disorders. (from martindale, the extra pharmacopoeia, 30th ed, p810)Chlormerodrin
a mercurial compound that has been used as a diuretic but is now superseded by more potent and less toxic drugs. the radiolabeled form has been used as a diagnostic and research tool.Chlorothiazide
a thiazide diuretic with actions and uses similar to those of hydrochlorothiazide. (from martindale, the extra pharmacopoeia, 30th ed, p812)Chlorthalidone
a benzenesulfonamide-phthalimidine that tautomerizes to a benzophenones form. it is considered a thiazide-like diuretic.Clopamide
a sulfamoylbenzamide piperidine. it is considered a thiazide-like diuretic.Cyclopenthiazide
thiazide diuretic also used as an antihypertensive agent.Dichlorphenamide
a carbonic anhydrase inhibitor that is used in the treatment of glaucoma.Ethoxzolamide
a carbonic anhydrase inhibitor used as diuretic and in glaucoma. it may cause hypokalemia.Hydrochlorothiazide
a thiazide diuretic often considered the prototypical member of this class. it reduces the reabsorption of electrolytes from the renal tubules. this results in increased excretion of water and electrolytes, including sodium, potassium, chloride, and magnesium. it is used in the treatment of several disorders including edema, hypertension, diabetes insipidus, and hypoparathyroidism.Hydroflumethiazide
a thiazide diuretic with actions and uses similar to those of hydrochlorothiazide. (from martindale, the extra pharmacopoeia, 30th ed, p822)Mefruside
a benzene-sulfonamide-furan. it is used as a diuretic that affects the concentrating ability of the kidney, increases sodium chloride excretion, but may not spare potassium. it inhibits carbonic anhydrases and may increase the blood uric acid level.Mersalyl
a toxic thiol mercury salt formerly used as a diuretic. it inhibits various biochemical functions, especially in mitochondria, and is used to study those functions.Methazolamide
a carbonic anhydrase inhibitor that is used as a diuretic and in the treatment of glaucoma.Methyclothiazide
a thiazide diuretic with properties similar to those of hydrochlorothiazide. (from martindale, the extra pharmacopoeia, 30th ed, p825)Metolazone
a quinazoline-sulfonamide derived diuretic that functions by inhibiting sodium chloride symporters.Polythiazide
a thiazide diuretic with actions and uses similar to those of hydrochlorothiazide. (from martindale, the extra pharmacopoeia, 30th ed, p826)Triamterene
a pteridinetriamine compound that inhibits sodium reabsorption through sodium channels in renal epithelial cells.Trichlormethiazide
a thiazide diuretic with properties similar to those of hydrochlorothiazide. (from martindale, the extra pharmacopoeia, 30th ed, p830)Fosfomycin
an antibiotic produced by streptomyces fradiae.Tromethamine
an organic amine proton acceptor. it is used in the synthesis of surface-active agents and pharmaceuticals; as an emulsifying agent for cosmetic creams and lotions, mineral oil and paraffin wax emulsions, as a biological buffer, and used as an alkalizer. (from merck, 11th ed; martindale, the extra pharmacopoeia, 30th ed, p1424)Xipamide
a sulfamoylbenzamide analog of clopamide. it is diuretic and saluretic with antihypertensive activity. it is bound to plasma proteins, thus has a delayed onset and prolonged action.
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 T50.2X5S to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About T50.2X5SOverview
Is T50.2X5S a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report adverse effect of carbonic-anhydrase inhibitors, benzothiadiazides and other diuretics, sequela on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character S in T50.2X5S mean?
The final character S makes this a sequela code: it reports a lingering problem that remains after the adverse effect of carbonic-anhydrase inhibitors, benzothiadiazides and other diuretics itself has resolved, not the original event.
What MS-DRG does T50.2X5S group to?
On inpatient claims, adverse effect of carbonic-anhydrase inhibitors, benzothiadiazides and other diuretics, 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 T50.2X5S be a principal diagnosis?
No. The Medicare Code Editor rejects this code as a principal diagnosis because adverse effect of carbonic-anhydrase inhibitors, benzothiadiazides and other diuretics, sequela describes a circumstance that influences health status rather than a current illness. Report it as a secondary diagnosis.
Is T50.2X5S 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 carbonic-anhydrase inhibitors, benzothiadiazides and other diuretics, 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.
