Medically reviewed by Drugs.com. Last updated on Apr 25, 2022.
The Mykrox brand name has been discontinued in the U.S. If generic versions of this product have been approved by the FDA, there may be generic equivalents available.
Commonly used brand name(s)
In the U.S.
Available Dosage Forms:
Therapeutic Class: Cardiovascular Agent
Pharmacologic Class: Diuretic
Chemical Class: Thiazide Related
Uses for Mykrox
Metolazone is used to treat fluid retention (edema) and swelling that is caused by congestive heart failure, kidney disease, or other medical conditions .
Metolazone is also used alone or together with other medicines to treat high blood pressure (hypertension). High blood pressure adds to the work load of the heart and arteries. If it continues for a long time, the heart and arteries may not function properly. This can damage the blood vessels of the brain, heart, and kidneys, resulting in a stroke, heart failure, or kidney failure. High blood pressure may also increase the risk of heart attacks. These problems may be less likely to occur if blood pressure is controlled .
Metolazone is a thiazide diuretic (water pill). It reduces the amount of water in the body by increasing the flow of urine, which helps to lower blood pressure .
This medicine is available only with your doctor's prescription .
Before using Mykrox
In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:
Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.
Appropriate studies have not been performed on the relationship of age to the effects of metolazone in the pediatric population. Safety and efficacy have not been established .
Appropriate studies performed to date have not demonstrated geriatrics-specific problems that would limit the usefulness of metolazone in the elderly. However, elderly patients are more likely to have age-related kidney, liver, or heart problems, which may require an adjustment in the dose for patients receiving metolazone .
There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.
Interactions with medicines
Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.
Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
- Amtolmetin Guacil
- Arsenic Trioxide
- Choline Salicylate
- Ethacrynic Acid
- Flufenamic Acid
- Mefenamic Acid
- Niflumic Acid
- Nimesulide Beta Cyclodextrin
- Salicylic Acid
- Sodium Salicylate
- Tiaprofenic Acid
- Tolfenamic Acid
Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
- Aminolevulinic Acid
Interactions with food/tobacco/alcohol
Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.
Using this medicine with any of the following is usually not recommended, but may be unavoidable in some cases. If used together, your doctor may change the dose or how often you use this medicine, or give you special instructions about the use of food, alcohol, or tobacco.
Other medical problems
The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:
- Anuria (not able to pass urine) or
- Liver disease, severe (e.g., hepatic coma)—Should not be used in patients with these conditions .
- Asthma or
- Diabetes or
- Gout or
- Hypercalcemia (high calcium in the blood) or
- Hyperuricemia (high uric acid in the blood) or
- Hypochloremia (low chloride in the blood) or
- Hypokalemia (low potassium in the blood) or
- Hypomagnesemia (low magnesium in the blood) or
- Hyponatremia (low sodium in the blood) or
- Systemic lupus erythematosus—Use with caution. This medicine may make these conditions worse .
- Kidney disease or
- Liver disease—Use with caution. The effects of the medicine may be increased because of slower removal of the medicine from the body .
Proper use of Mykrox
This section provides information on the proper use of a number of products that contain metolazone. It may not be specific to Mykrox. Please read with care.
In addition to the use of this medicine, treatment for your high blood pressure may include weight control and changes in the types of foods you eat, especially foods high in sodium or potassium. Your doctor will tell you which of these are most important for you. You should check with your doctor before changing your diet .
Many patients who have high blood pressure will not notice any signs of the problem. In fact, many may feel normal. It is very important that you take your medicine exactly as directed and that you keep your appointments with your doctor even if you feel well .
Remember that this medicine will not cure your high blood pressure, but it does help control it. You must continue to take it as directed if you expect to lower your blood pressure and keep it down. You may have to take high blood pressure medicine for the rest of your life. If high blood pressure is not treated, it can cause serious problems such as heart failure, blood vessel disease, stroke, or kidney disease .
Use only the brand of this medicine that your doctor prescribed. Different brands may not work the same way .
The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.
The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.
- For oral dosage form (tablets):
- For fluid retention (edema):
- Adults—At first, 5 to 20 milligrams (mg) once a day. Your doctor may adjust your dose if needed.
- Children—Use and dose must be determined by your doctor .
- For high blood pressure:
- Adults—At first, 2.5 to 5 milligrams (mg) once a day. Your doctor may adjust your dose if needed.
- Children—Use and dose must be determined by your doctor .
- For fluid retention (edema):
If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.
Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.
Keep out of the reach of children.
Do not keep outdated medicine or medicine no longer needed.
Ask your healthcare professional how you should dispose of any medicine you do not use.
Precautions while using Mykrox
It is very important that your doctor check your progress at regular visits to make sure this medicine is working properly. Blood or urine tests may be needed to check for unwanted effects .
Check with your doctor right away if you have any of the following symptoms while taking this medicine: convulsions or seizures; decreased urine; drowsiness; dry mouth; excessive thirst; muscle pains or cramps; nausea or vomiting; increased heart rate or pulse; or unusual tiredness or weakness. These may be symptoms of a condition called hypokalemia or potassium loss .
Dizziness, lightheadedness, or fainting may occur, especially when you get up from a lying or sitting position. Getting up slowly may help. If the problem continues or gets worse, check with your doctor .
Drinking alcoholic beverages may also make the dizziness, lightheadedness, or fainting worse. While you are taking this medicine, be careful to limit the amount of alcohol you drink .
This medicine may cause changes in your blood sugar levels. If you notice a change in the results of your blood or urine sugar tests or if you have any questions, check with your doctor .
Before you have any medical tests, tell the medical doctor in charge that you are taking this medicine. The results of some tests (e.g., tests for parathyroid function) may be affected by this medicine .
Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements .
Mykrox side effects
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor immediately if any of the following side effects occur:
Incidence not known
- Black, tarry stools
- bleeding gums
- blistering, peeling, or loosening of skin
- blood in urine or stools
- blurred vision
- bone pain
- chest pain
- clay-colored stools
- cold sweats
- dark urine
- decreased urine
- dizziness, faintness, or lightheadedness when getting up from lying or sitting position
- dry mouth
- fast, irregular, pounding, or racing heartbeat or pulse
- flushed, dry skin
- fruit-like breath odor
- general tiredness and weakness
- incoherent speech
- increased hunger
- increased thirst
- increased urination
- joint or muscle pain
- light-colored stools
- loss of appetite
- lower back or side pain
- metallic taste
- mood changes
- muscle pain or cramps
- nausea and vomiting
- numbness or tingling in hands, feet, or lips
- pain in lower legs
- painful or difficult urination
- pinpoint red spots on skin
- red irritated eyes
- red skin lesions, often with a purple center
- redness or swelling of lower leg
- shortness of breath
- sore throat
- sores, ulcers, or white spots in mouth or on lips
- sugar in the urine
- swelling of face, ankles, or hands
- swollen or painful glands
- tightness in chest
- troubled breathing
- unexplained weight loss
- unpleasant breath odor
- unusual bleeding or bruising
- unusual tiredness or weakness
- upper right abdominal pain
- vomiting of blood
- weak pulse
- yellow eyes and skin
Get emergency help immediately if any of the following symptoms of overdose occur:
Symptoms of overdose
- irregular, fast or slow, or shallow breathing
- pale or blue lips, fingernails, or skin
- unusual drowsiness, dullness, tiredness, weakness, or feeling of sluggishness
- weakness and heaviness of legs
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
Incidence not known
- Blue-green to black skin discoloration
- burning, tingling, numbness, or pain in the hands, arms, feet, or legs
- cracked, dry, or scaly skin
- decreased interest in sexual intercourse
- feeling of constant movement of self or surroundings
- hives or welts
- inability to have or keep an erection
- loss in sexual ability, desire, drive, or performance
- pain, redness, or sloughing of skin at place of injection
- sensation of pins and needles
- sensation of spinning
- stabbing pain
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
More about Mykrox (metolazone)
- Side effects
- Drug interactions
- Dosage information
- During pregnancy or Breastfeeding
- Drug class: thiazide diuretics
- Other brands
Related treatment guides
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.