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Generic Name: chlorthalidone (klor THAL i done)
Brand Name: Thalitone, Hygroton

Medically reviewed by on Feb 25, 2019 – Written by Cerner Multum

What is chlorthalidone?

Chlorthalidone is a thiazide diuretic (water pill) that helps prevent your body from absorbing too much salt, which can cause fluid retention.

Chlorthalidone treats fluid retention (edema) in people with congestive heart failure, cirrhosis of the liver, or kidney disorders, or edema caused by taking steroids or estrogen. Chlorthalidone is also used to treat high blood pressure (hypertension).

Chlorthalidone may also be used for purposes not listed in this medication guide.

Important Information

You should not use chlorthalidone if you are unable to urinate, or if you are allergic to sulfa drugs.

Before taking this medicine

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

  • you are unable to urinate; or

  • you are allergic to sulfa drugs.

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

It is not known whether chlorthalidone will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant.

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

How should I take chlorthalidone?

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

Your doctor may recommend you eat certain foods or take supplements to keep your potassium from getting too low. Follow the diet and medication plan created for you by your doctor or nutrition counselor.

While using chlorthalidone, your blood pressure will need to be checked often. Your blood and urine may both be tested if you have been vomiting or are dehydrated.

Chlorthalidone can interfere with the results of a thyroid test. Tell any doctor who treats you that you are using a thiazide diuretic.

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 this medicine at room temperature away from moisture, heat, and light. Keep the bottle tightly closed when not in use. Do not allow liquid chlorthalidone to freeze.

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.

Overdose symptoms may include nausea, weakness, dizziness, drowsiness, extreme thirst, muscle pain, or rapid heartbeats.

What should I avoid while taking chlorthalidone?

Drinking alcohol with chlorthalidone can cause side effects.

Avoid getting up too fast from a sitting or lying position, or you may feel dizzy. Get up slowly and steady yourself to prevent a fall.

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.

Chlorthalidone 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.

Call your doctor at once if you have:

  • a light-headed feeling, like you might pass out;

  • little or no urination;

  • severe pain in your upper stomach spreading to your back;

  • pale or yellowed skin, dark colored urine, fever, easy bruising or bleeding;

  • high levels of calcium in your blood--nausea, vomiting, constipation, increased thirst or urination, muscle weakness, bone pain, confusion, lack of energy, or tired feeling;

  • low levels of sodium in the body--headache, confusion, slurred speech, severe weakness, vomiting, loss of coordination, feeling unsteady;

  • low potassium--leg cramps, constipation, irregular heartbeats, fluttering in your chest, increased thirst or urination, numbness or tingling, muscle weakness or limp feeling; or

  • other signs of an an electrolyte imbalance--dry mouth, thirst, nausea, vomiting, drowsiness, feeling weak or restless, muscle pain, fast heart rate, seizure (convulsions).

Common side effects may include:

  • dizziness, spinning sensation;

  • nausea, vomiting, diarrhea, constipation;

  • muscle spasm; or

  • impotence, sexual problems.

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.

Chlorthalidone dosing information

Usual Adult Dose for Hypertension:

-Initial dose: 25 mg orally once a day
-Titration: Increase to 50 mg orally once a day if response is inadequate; if response is still inadequate, increase to 100 mg orally once a day, or a second antihypertensive drug (step 2 therapy) may be added
-Maintenance dose: 25 to 100 mg orally once a day
-Maximum dose: 100 mg orally once a day

-Doses should be taken in the morning with food.
-Maintenance doses may be lower than initial doses and should be adjusted according to individual patient response.
-Effectiveness is well sustained during continued use.

Use: Hypertension (alone or with another antihypertensive drug)

Usual Adult Dose for Edema:

-Initial dose: 50 to 100 mg orally once a day, or 100 mg orally every other day; some patients may require 150 to 200 mg orally at these intervals
-Maximum dose: 200 mg orally once a day

-Doses should be taken in the morning with food.
-Maintenance doses may be lower than initial doses and should be adjusted according to individual patient response.
-Effectiveness is well sustained during continued use.

Use: For edema due to various forms of renal dysfunction, such as nephrotic syndrome, acute glomerulonephritis, and chronic renal failure

What other drugs will affect chlorthalidone?

Taking chlorthalidone with other drugs that make you light-headed can worsen this effect. Ask your doctor before taking chlorthalidone with a cold or allergy medicine, sleeping pill, narcotic pain medicine, muscle relaxer, or medicine for anxiety, depression, or seizures.

Tell your doctor about all your current medicines and any you start or stop using, especially:

  • other blood pressure medications;

  • digoxin, digitalis;

  • lithium;

  • insulin or oral diabetes medicine; or

  • steroid medicine.

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

Further information

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.