February 27, 2017
Recommended Topic Related To:


"What are diuretics and how do they work?

The amount of fluid (water) retained by the body is controlled primarily by the kidneys. This occurs due to the kidney's ability to control the retention and elimination of sodium and chlorid"...



Mykrox Side Effects Center

Medical Editor: John P. Cunha, DO, FACOEP

Last reviewed on RxList 1/4/2016

Mykrox (metolazone) Tablet is a diuretic (water pill) and antihypertensive drug used to treat high blood pressure. Mykrox is available in generic form. Common side effects of Mykrox include dizziness, headache, muscle cramps, fatigue, joint pain and swelling, chest pain, lightheadedness, blurred vision, loss of appetite, stomach upset, diarrhea, or constipation.

The recommended dosage of Mykrox is one tablet taken once a day. Zaroxolyn, Furosemide, alcohol, narcotics, diuretics, corticosteroids, lithium, insulin, and methenamine may interact with Mykrox. Tell your doctor all medications you take. Before taking Mykrox tell your doctor if you have impaired renal function. If you are pregnant only take Mykrox if clearly needed. Do not take Mykrox if you are breastfeeding.

Our Mykrox (metolazone) Tablet Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

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.

What is Prescribing information?

The FDA package insert formatted in easy-to-find categories for health professionals and clinicians.

Mykrox FDA Prescribing Information: Side Effects
(Adverse Reactions)


Adverse experience information is available from more than 14 years of accumulated marketing experience with other formulations of metolazone for which reliable quantitative information is lacking and from controlled clinical trials with MYKROX (metolazone) from which incidences can be calculated.

In controlled clinical trials with MYKROX (metolazone) , adverse experiences resulted in discontinuation of therapy in 6.7-6.8% of patients given ½ to 1 mg of MYKROX (metolazone) .

Adverse experiences occurring in controlled clinical trials with MYKROX (metolazone) with an incidence of > 2%, whether or not considered drugrelated, are summarized in the following table.

Incidence of Adverse Experiences Volunteered or Elicited (by Patient in Percent)*

n = 226†
Dizziness (lightheadedness) 10.2
Headaches 9.3
Muscle Cramps 5.8
Fatigue (malaise, lethargy, lassitude) 4.4
Joint Pain, swelling 3.1
Chest Pain (precordial discomfort) 2.7
* Percent of patients reporting an adverse experience one or more times.
† All doses combined (½, 1, and 2 mg).

Some of the adverse effects reported in association with MYKROX (metolazone) also occur frequently in untreated hypertensive patients, such as headache and dizziness, which occurred in 14.8 and 7.4% of patients in a smaller parallel placebo group.

The following adverse effects were reported in less than 2% of the MYKROX (metolazone) treated patients.


Cold extremities, edema, orthostatic hypotension, palpitations.

Central and Peripheral Nervous System

Anxiety, depression, dry mouth, impotence, nervousness, neuropathy, weakness, “weird” feeling.


Pruritus, rash, skin dryness.

Eyes, Ears, Nose, Throat

Cough, epistaxis, eye itching, sinus congestion, sore throat, tinnitus.


Abdominal discomfort (pain, bloating), bitter taste, constipation, diarrhea, nausea, vomiting.




Back pain.

Other Adverse Experiences

Adverse experiences reported with other marketed metolazone formulations and most thiazide diuretics, for which quantitative data are not available, are listed in decreasing order of severity within body systems. Several are single or rare occurrences.


excessive volume depletion, hemoconcentration, venous thrombosis.

Central and Peripheral Nervous System

syncope, paresthesias, drowsiness, restlessness (sometimes resulting in insomnia).


toxic epidermal necrolysis (TEN), Stevens-Johnson Syndrome, necrotizing angiitis (cutaneous vasculitis), skin necrosis, purpura, petechiae, dermatitis, photosensitivity, urticaria, pruritus, skin rashes.


hepatitis, intrahepatic cholestatic jaundice, pancreatitis, anorexia, nausea, diarrhea, abdominal pain.


aplastic (hypoplastic) anemia, agranulocytosis, leukopenia, thrombocytopenia.


hypokalemia (see WARNINGS, Hypokalemia), hyponatremia, hyperuricemia, hypochloremia, hypochloremic alkalosis, hyperglycemia, glycosuria, increase in serum urea nitrogen (BUN) or creatinine, hypophosphatemia, hypomagnesemia, hypercalcemia.


acute gouty attacks.


transient blurred vision, chills.

In addition, rare adverse experiences reported in association with similar antihypertensive-diuretics but not reported to date for metolazone include: sialadenitis, xanthopsia, respiratory distress (including pneumonitis), and anaphylactic reactions. These experiences could occur with clinical use of metolazone.

Read the entire FDA prescribing information for Mykrox (Metolazone)

Report Problems to the Food and Drug Administration


You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.


Get tips on handling your hypertension.