Chlorthalidone (By mouth)

Chlorthalidone (klor-THAL-i-done)

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

Brand Name(s):

Hemiclor, Thalitone

When This Medicine Should Not Be Used:

How to Use This Medicine:

Tablet

• Your doctor will tell you how much medicine to use. Do not use more than directed.
• It is best to take this medicine with food or milk.
• Missed dose: 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.
• Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light.

Drugs and Foods to Avoid:

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

• Some foods and medicines can affect how chlorthalidone works. Tell your doctor if you are also using any of the following:
  • Bepridil, cholestyramine, colestipol, digoxin, lithium, or tubocurarine
  • Diabetes medicine
  • Other blood pressure medicines
  • Steroid medicine
• Do not drink alcohol while you are using this medicine.

Warnings While Using This Medicine:

• Hemiclor™: It is not safe to take this medicine during pregnancy. It could harm an unborn baby. Tell your doctor right away if you become pregnant.
• Hemiclor™: Do not breastfeed during treatment with this medicine.
• Tell your doctor if you are pregnant or breastfeeding, or if you have kidney disease, liver disease, heart disease, heart failure, diabetes, gout, lupus, pancreas problems, or trouble urinating. Tell your doctor if you are on a low-salt diet.
• This medicine may cause kidney problems.
• This medicine may make you dizzy. Avoid driving, using machines, or doing anything else that could be dangerous if you are not alert.
• 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.
• Keep all medicine out of the reach of children. Never share your medicine with anyone.

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
• Change in how much or how often you urinate, bloody or cloudy urine
• Confusion, weakness, uneven heartbeat, trouble breathing, numbness or tingling in the hands, feet, or lips
• Dry mouth, increased thirst, muscle cramps, nausea or vomiting
• Fever chills, cough, hoarseness
• Lightheadedness, dizziness, fainting

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

• Loss of appetite
• Mild diarrhea 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: 8/4/2025