Medically reviewed on April 11, 2018.
What is methyclothiazide?
Methyclothiazide is a thiazide diuretic (water pill) that helps prevent your body from absorbing too much salt, which can cause fluid retention.
Methyclothiazide is used to treat high blood pressure (hypertension).
Methyclothiazide may also be used for purposes not listed in this medication guide.
You should not use methyclothiazide if you are unable to urinate.
What should I discuss with my doctor before taking methyclothiazide?
You should not use methyclothiazide if you are allergic to it, or if you are unable to urinate.
To make sure methyclothiazide is safe for you, tell your doctor if you have:
an electrolyte imbalance (such as low levels of potassium in your blood);
high cholesterol or triglycerides (a type of fat in the blood);
an allergy to sulfa drugs; or
if you have recently had surgery.
FDA pregnancy category B. Methyclothiazide is not expected to harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant during treatment.
Methyclothiazide can pass into breast milk and may harm a nursing baby. You should not breast-feed while using this medicine.
How should I take methyclothiazide?
Follow all directions on your prescription label. Your doctor may occasionally change your dose to make sure you get the best results. Do not take this medicine in larger or smaller amounts or for longer than recommended.
Your blood pressure will need to be checked often.
This medicine can cause unusual results with certain medical tests. Tell any doctor who treats you that you are using methyclothiazide.
If you need surgery, tell the surgeon ahead of time that you are using methyclothiazide. You may need to stop using the medicine for a short time.
If you are being treated for high blood pressure, keep 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 at room temperature away from moisture, heat, and light.
What happens if I miss a dose?
Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.
What happens if I overdose?
Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.
What should I avoid while taking methyclothiazide?
Drinking alcohol can increase certain side effects of methyclothiazide.
Avoid becoming overheated or dehydrated during exercise and in hot weather. 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.
Methyclothiazide side effects
Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.
Call your doctor at once if you have:
weakness, drowsiness, lack of energy;
a light-headed feeling, like you might pass out;
little or no urinating;
pale or yellowed skin, dark colored urine, fever, confusion or weakness;
anxiety, sweating, severe shortness of breath, cough with foamy mucus, chest pain; or
electrolyte imbalance--dry mouth, increased thirst, drowsiness, restless feeling, confusion, nausea, vomiting, increased urination, muscle pain or weakness, fast heart rate, fainting, or seizure (convulsions).
Common side effects may include:
headache, dizziness, tingly feeling;
nausea, vomiting, diarrhea, constipation, loss of appetite; or
This is not a complete list of side effects and others may occur. Tell your doctor about any unusual or bothersome side effect. You may report side effects to FDA at 1-800-FDA-1088.
See also: Side effects (in more detail)
Methyclothiazide dosing information
Usual Adult Dose for Hypertension:
2.5 to 5 mg orally once a day
Comments: If blood pressure remains uncontrolled after 8 to 12 weeks at 5 mg once a day, another antihypertensive drug should be added.
Uses: Treatment of mild to moderate hypertension as monotherapy; treatment of more severe hypertension when used concomitantly with other antihypertensive drugs.
Usual Adult Dose for Edema:
2.5 to 10 mg orally once a day
Maximum dose: 10 mg
Uses: Adjunctive treatment of edema associated with congestive heart failure, hepatic cirrhosis, and corticosteroid and estrogen therapy; this drug has also been useful in edema due to various forms of renal dysfunction (e.g., nephrotic syndrome, acute glomerulonephritis, and chronic renal failure).
What other drugs will affect methyclothiazide?
Taking this medicine with other drugs that can lower blood pressure can worsen this effect. Ask your doctor before taking methyclothiazide with a narcotic medicine, or medicine for anxiety or seizures (butabarbital, phenobarbital, secobarbital, and others).
Tell your doctor about all medicines you use, and those you start or stop using during your treatment with methyclothiazide, especially:
any other blood pressure medicines;
insulin or oral diabetes medicine;
steroid medicine (prednisone and others).
This list is not complete. Other drugs may interact with methyclothiazide, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.
Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
Copyright 1996-2018 Cerner Multum, Inc. Version: 2.01.
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- Drug class: thiazide diuretics