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Metolazone (By mouth)

Metolazone (me-TOL-a-zone)

Treats high blood pressure and fluid retention (edema). This medicine is a diuretic ("water pill").

Brand Name(s):

There may be other brand names for this medicine.

When This Medicine Should Not Be Used:

You should not use this medicine if you have had an allergic reaction to metolazone, sulfa drugs (such as sulfamethoxazole, sulfasalazine, sulfisoxazole, Azulfidine®, Bactrim®, Gantrisin®, or Septra®), or other diuretics ("water pills"). You should not use this medicine if you are not able to form urine (anuria) or have severe liver disease.

How to Use This Medicine:


  • Take your medicine as directed. Your dose may need to be changed several times to find what works best for you.
  • Use only the brand of medicine your doctor prescribed. Other brands may not work the same way.
  • Carefully follow your doctor's instructions about any special diet. You may need to eat foods that are high in potassium (such as oranges or bananas) to prevent potassium loss while you are using this medicine.

If a dose is missed:

  • Take a dose as soon as you remember. If it is almost time for your next dose, wait until then and take a regular dose. Do not take extra medicine to make up for a missed dose.

How to Store and Dispose of This Medicine:

  • Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light.
  • Ask your pharmacist, doctor, or health caregiver about the best way to dispose of any outdated medicine or medicine no longer needed.
  • Keep all medicine out of the reach of children. Never share your medicine with anyone.

Drugs and Foods to Avoid:

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

  • Make sure your doctor knows if you are using digoxin (Lanoxin®), other medicine for high blood pressure (such as atenolol, bepridil, metoprolol, propranolol, timolol, Vascor®, or Toprol®), or a diuretic or "water pill" (such as amiloride, bumetanide, ethacrynic acid, furosemide, hydrochlorothizide [HCTZ], quinethazone, spironolactone, torsemide, triamterene, Aldactone®, Bumex®, Demadex®, Hydromox®, or Lasix®).
  • Make sure your doctor knows if you are also using a blood thinner (such as warfarin, Coumadin®), cholestyramine (Questran®), colestipol (Colestid®), lithium (Eskalith®, Lithobid®), methenamine, norepinephrine, tubocurarine, pain or arthritis medicine (such as aspirin, Advil®, Aleve®, Indocin®, Motrin®, Orudis®, Relafen®, or Voltaren®), or a steroid medicine (such as cortisone, dexamethasone, prednisone, or Medrol®), or low-salt milk. Tell your doctor if you are using insulin, diabetes medicines that you take by mouth (such as glyburide, metformin, Actos®, Avandia®, Glucotrol®, Glucovance®), narcotic pain relievers, phenobarbital, or other sedatives.
  • Ask your doctor before you use potassium supplements or salt substitutes that contain potassium.
  • Do not drink alcohol while you are using this medicine.

Warnings While Using This Medicine:

  • Make sure your doctor knows if you are pregnant or breastfeeding, or if you have kidney disease, heart disease, congestive heart failure, low blood pressure, mineral imbalance (high or low calcium, magnesium, phosphorus, potassium, or sodium in the blood), or a history of asthma. Tell your doctor if you have diabetes, gout, lupus, or severe diarrhea.
  • This medicine may make you dizzy. Avoid driving, using machines, or doing anything else that could be dangerous if you are not alert.
  • Tell any doctor or dentist who treats you that you are using this medicine. You may need to stop using this medicine several days before you have surgery or medical tests.
  • This medicine may make your skin more sensitive to sunlight. Wear sunscreen. Do not use sunlamps or tanning beds.
  • Your doctor will do lab tests at regular visits to check on the effects of this medicine. Keep all appointments.
  • If you stop using this medicine, your blood pressure may go up. High blood pressure usually has no symptoms. Even if you feel well, do not stop using the medicine without asking your doctor.

Possible Side Effects While Using This Medicine:

Call your doctor right away if you notice any of these side effects:

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
  • Blistering, peeling, or red skin rash.
  • Blood in the urine or stools.
  • Change in how much or how often you urinate.
  • Chest pain (may be related to your disease and not a side effect).
  • Confusion, weakness, shortness of breath, or numbness or tingling in hands, feet, or lips.
  • Dark-colored urine or pale stools.
  • Dry mouth, increased thirst, muscle cramps, nausea, or vomiting.
  • Fast, pounding, or uneven heartbeat.
  • Fever chills, cough, hoarseness, sore throat, and body aches.
  • Lightheadedness, dizziness, or fainting.
  • Problems urinating, pain in side or lower back.
  • Unusual bleeding, bruising, or weakness.
  • Yellowing of your skin or the whites of your eyes.

If you notice these less serious side effects, talk with your doctor:

  • Blurred vision, headache.
  • Loss of appetite.
  • Mild diarrhea, constipation, stomach pain, or stomach upset.
  • Problems having sex.

If you notice other side effects that you think are caused by this medicine, tell your doctor

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088

Last Updated: 5/1/2020

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites.

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