FDA label 58478564-4520-aa3e-e063-6294a90aa860

openFDA label record#

This page contains supplementary openFDA label data. For the canonical label presentation, use the corresponding DailyMed Structured Product Label.

Verified complete openFDA source JSON (canonical bytes are SHA-256 checked before publication)

SPL set ID
9ab471a1-0f71-4452-ba57-518dcc6f9f18
SPL ID
58478564-4520-aa3e-e063-6294a90aa860
Version
3
Effective date
2026-08-05
Source export date
2026-09-28
Source partition
12
Source file
https://download.open.fda.gov/drug/label/drug-label-0012-of-0014.json.zip
Source object key
raw/openfda/drug-label/2026-09-28/663999d0fe1757c1e2cd13a4799d76d875f663e0bc57701092264ebe7febfc18/drug-label-0012-of-0014.json.zip
Source manifest SHA-256
cd2e66336a5cd2223fa3995098fdbdb84c6a7ee5c0a4addb236ccb22dd1e6887
Import run
20260929T050834Z
Imported at
2026-09-29 06:28:58

Boxed warning cross-check#

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boxed warning

DO NOT INTERCHANGE DO NOT INTERCHANGE METOLAZONE TABLETS, USP, ZAROXOLYN ® TABLETS, AND OTHER FORMULATIONS OF METOLAZONE THAT SHARE THEIR SLOW AND INCOMPLETE BIOAVAILABILITY AND ARE NOT THERAPEUTICALLY EQUIVALENT AT THE SAME DOSES TO MYKROX ® TABLETS, A MORE RAPIDLY AVAILABLE AND COMPLETELY BIOAVAILABLE METOLAZONE PRODUCT. FORMULATIONS BIOEQUIVALENT TO ZAROXOLYN AND FORMULATIONS BIOEQUIVALENT TO MYKROX SHOULD NOT BE INTERCHANGED FOR ONE ANOTHER.

Warnings cross-check#

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warnings

WARNINGS Rapid Onset Hyponatremia And/Or Hypokalemia Rarely, the rapid onset of severe hyponatremia and/or hypokalemia has been reported following initial doses of thiazide and non-thiazide diuretics. When symptoms consistent with severe electrolyte imbalance appear rapidly, drug should be discontinued and supportive measures should be initiated immediately. Parenteral electrolytes may be required. Appropriateness of therapy with this class of drugs should be carefully reevaluated. Hypokalemia Hypokalemia may occur with consequent weakness, cramps, and cardiac dysrhythmias. Serum potassium should be determined at regular and appropriate intervals, and dose reduction, potassium supplementation or addition of a potassium-sparing diuretic instituted whenever indicated. Hypokalemia is a particular hazard in patients who are digitalized or who have or have had a ventricular arrhythmia; dangerous or fatal arrhythmias may be precipitated. Hypokalemia is dose related. Concomitant Therapy Lithium In general, diuretics should not be given concomitantly with lithium because they reduce its renal clearance and add a high risk of lithium toxicity. Read prescribing information for lithium preparations before use of such concomitant therapy. Furosemide Unusually large or prolonged losses of fluids and electrolytes may result when metolazone tablets are administered concomitantly to patients receiving furosemide (see PRECAUTIONS, Drug Interactions ). Other Antihypertensive Drugs When metolazone tablets are used with other antihypertensive drugs, particular care must be taken to avoid excessive reduction of blood pressure, especially during initial therapy. Cross-Allergy Cross-allergy may occur when metolazone tablets are given to patients known to be allergic to sulfonamide-derived drugs, thiazides, or quinethazone. Sensitivity Reactions Sensitivity reactions (e.g., angioedema, bronchospasm) may occur with or without a history of allergy or bronchial asthma and may occur with the first dose of metolazone tablets.

Adverse reactions cross-check#

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adverse reactions

ADVERSE REACTIONS Metolazone tablets are usually well tolerated, and most reported adverse reactions have been mild and transient. Many of metolazone tablets related adverse reactions represent extensions of its expected pharmacologic activity and can be attributed to either its antihypertensive action or its renal/metabolic actions. The following adverse reactions have been reported. Several are single or comparably rare occurrences. Adverse reactions are listed in decreasing order of severity within body systems. Cardiovascular Chest pain/discomfort, orthostatic hypotension, excessive volume depletion, hemoconcentration, venous thrombosis, palpitations. Central And Peripheral Nervous System Syncope, neuropathy, vertigo, paresthesias, psychotic depression, impotence, dizziness/lightheadedness, drowsiness, fatigue, weakness, restlessness (sometimes resulting in insomnia), headache. Dermatologic/Hypersensitivity Toxic epidermal necrolysis (TEN), Stevens-Johnson Syndrome, necrotizing angiitis (cutaneous vasculitis), skin necrosis, purpura, petechiae, dermatitis (photosensitivity), urticaria, pruritus, skin rashes. Gastrointestinal Hepatitis, intrahepatic cholestatic jaundice, pancreatitis, vomiting, nausea, epigastric distress, diarrhea, constipation, anorexia, abdominal bloating, abdominal pain. Hematologic Aplastic/hypoplastic anemia, agranulocytosis, leukopenia, thrombocytopenia. Metabolic Hypokalemia, hyponatremia, hyperuricemia, hypochloremia, hypochloremic alkalosis, hyperglycemia, glycosuria, increase in serum urea nitrogen (BUN) or creatinine, hypophosphatemia, hypomagnesemia, hypercalcemia. Musculoskeletal Joint pain, acute gouty attacks, muscle cramps or spasm. Other Transient blurred vision, chills, dry mouth. In addition, adverse reactions reported with similar antihypertensive-diuretics, but which have not been reported to date for metolazone tablets include: bitter taste, sialadenitis, xanthopsia, respiratory distress (including pneumonitis), and anaphylactic reactions. These reactions should be considered as possible occurrences with clinical usage of metolazone tablets. Whenever adverse reactions are moderate or severe, metolazone tablets dosage should be reduced or therapy withdrawn. To report SUSPECTED ADVERSE REACTIONS, contact Micro Labs USA, Inc. at 1-855-839-8195 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

Reported adverse events (FAERS/openFDA)#

Adverse event summaries are temporarily unavailable. Other product information remains available.