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Thiazide diuretics oral tablet (10 mg; 2.5 mg; 5 mg)

Metolazone

Generic name: metolazone

Brand names: Zaroxolyn, Mykrox

Last updated November 2, 2026 0 views
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What is metolazone?

Metolazone is a thiazide diuretic (water pill) that helps your body avoid taking in too much salt, which can lead to fluid retention.

Metolazone is used to treat fluid retention (edema) in people with congestive heart failure or a kidney disorder like nephrotic syndrome. Metolazone is also used to treat high blood pressure (hypertension).

Metolazone may also be used for reasons not mentioned in this medication guide.

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How should I take metolazone?

Follow all directions on your prescription label. Your doctor may sometimes change your dose to ensure you get the best results. Do not use this medicine in larger or smaller amounts or for longer than recommended.

Metolazone is usually taken only once per day.

You may need to limit salt in your diet while taking this medicine. Follow your doctor's instructions carefully.

While using metolazone, you may need frequent blood tests. Your blood and urine may both be tested if you have been vomiting or are dehydrated.

Metolazone can cause unusual results with certain medical tests. Inform any doctor who treats you that you are using metolazone.

If you need surgery, inform the surgeon in advance that you are using metolazone. You may need to stop using the medicine for a short time.

If you are being treated for high blood pressure, continue using this medicine even if you feel well. High blood pressure often has no symptoms. You may need to use blood pressure medicine for the rest of your life.

Store the tablets at room temperature away from heat, light, and moisture.

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Warnings

You should not use metolazone if you cannot urinate, or if you have severe liver disease.

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What should I discuss with my doctor before taking metolazone?

You should not use metolazone if you are allergic to it, or if you have:

  • severe liver disease; or
  • if you are unable to urinate.

To make sure metolazone is safe for you, tell your doctor if you have:

  • an electrolyte imbalance (such as low levels of potassium or magnesium in your blood);
  • a heart rhythm disorder;
  • an allergy to sulfa drugs;
  • liver disease;
  • kidney disease;
  • diabetes;
  • gout; or
  • systemic lupus erythematosus.

Using metolazone during pregnancy could cause side effects in the newborn baby, such as blood cell problems, or jaundice (yellowing of the skin or eyes). Tell your doctor if you are pregnant or if you become pregnant while using metolazone.

Metolazone can pass into breast milk and may harm a nursing baby. You should not breast-feed while using this medicine.

Metolazone is not approved for use by anyone younger than 18 years old.

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Metolazone side effects

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Metolazone may cause serious side effects. Call your doctor right away if you have:

  • chest pain;
  • pounding heartbeats or fluttering in your chest;
  • easy bruising or bleeding;
  • a light-headed feeling, like you might pass out;
  • liver problems--nausea, upper stomach pain, itching, tiredness, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes);
  • low potassium--leg cramps, constipation, irregular heartbeats, fluttering in your chest, increased thirst or urination, numbness or tingling, muscle weakness or limp feeling;
  • low levels of sodium in the body--headache, confusion, slurred speech, severe weakness, vomiting, loss of coordination, feeling unsteady;
  • other signs of an electrolyte imbalance--dry mouth, nausea, vomiting, weakness, drowsiness, lack of energy, muscle pain, little or no urination, or feeling restless; or
  • severe skin reaction--fever, sore throat, swelling in your face or tongue, burning in your eyes, skin pain followed by a red or purple skin rash that spreads (especially in the face or upper body) and causes blistering and peeling.

Common side effects of metolazone may include:

  • dizziness, spinning sensation;
  • drowsiness, tiredness;
  • depressed mood;
  • muscle or joint pain;
  • numbness or tingly feeling;
  • nausea, stomach pain, loss of appetite; or
  • diarrhea, constipation.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

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Metolazone dosing information

Usual Adult Dose for Hypertension:

Initial dose: 2.5 mg orally once a day (Zaroxolyn) or0.5 mg orally once a day (Mykrox).

Usual Adult Dose for Edema:

Initial dose: 5 mg orally once a day (Zaroxolyn) or0.5 mg orally once a day (Mykrox).

What happens if I miss a dose?

Take the missed dose as soon as you remember. If it is nearly time for your next dose, skip the missed dose. Do not take extra medicine to compensate for the missed dose.

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What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Overdose symptoms may include severe dizziness or drowsiness, dry mouth, thirst, muscle weakness, feeling light-headed, or fainting.

Drinking alcohol with metolazone can cause side effects.

Avoid becoming overheated or dehydrated during exercise, in hot weather, or by not drinking enough fluids. Follow your doctor's instructions about the type and amount of liquids you should drink. In some cases, drinking too much liquid can be as unsafe as not drinking enough.

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What other drugs will affect metolazone?

Taking this medicine with other drugs that make you feel light-headed can make that feeling worse. Ask your doctor before taking metolazone with a narcotic pain medicine, muscle relaxer, or medications for anxiety or seizures.

Tell your doctor about all the medicines you are currently taking and any that you start or stop using, especially:

  • any other blood pressure medication;
  • digoxin, digitalis;
  • furosemide or other diuretics (water pills);
  • insulin or oral diabetes medicine;
  • lithium;
  • methenamine;
  • vitamin D (at high doses);
  • a blood thinner--warfarin, Coumadin, Jantoven;
  • NSAIDs (nonsteroidal anti-inflammatory drugs)--ibuprofen (Advil, Motrin), naproxen (Aleve), celecoxib, diclofenac, indomethacin, meloxicam, and others;
  • salicylates--aspirin, Nuprin Backache Caplet, Kaopectate, KneeRelief, Pamprin Cramp Formula, Pepto-Bismol, Tricosal, Trilisate, and others; or
  • steroid medicine--prednisone and others.

This list is not complete. Other drugs may interact with metolazone, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.

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Related medicines

Before you take this medicine: the information on this page is general and may not cover your personal circumstances. Read the label supplied with your medicine and ask a pharmacist or doctor if you are unsure, especially if you are pregnant, breastfeeding, taking other medicines or managing a long-term condition.
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