Medically reviewed on February 19, 2018
What is chlorothiazide?
Chlorothiazide is a thiazide diuretic (water pill) that helps prevent your body from absorbing too much salt, which can cause fluid retention.
Chlorothiazide 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. Chlorothiazide is also used to treat high blood pressure (hypertension).
Chlorothiazide may also be used for purposes not listed in this medication guide.
You should not use chlorothiazide if you are unable to urinate, or if you are allergic to sulfa drugs.
Before taking this medicine
You should not use chlorothiazide if you are allergic to it, or if:
you are unable to urinate; or
you are allergic to sulfa drugs.
To make sure chlorothiazide is safe for you, tell your doctor if you have:
high cholesterol or triglycerides (a type of fat in the blood).
It is not known whether chlorothiazide will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant.
Chlorothiazide can pass into breast milk and may harm a nursing baby. You should not breast-feed while using this medicine.
How should I take chlorothiazide?
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.
Shake the oral suspension (liquid) well just before you measure a dose. Measure liquid medicine with the dosing syringe provided, or with a special dose-measuring spoon or medicine cup. If you do not have a dose-measuring device, ask your pharmacist for one.
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 chlorothiazide, 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.
Chlorothiazide 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 chlorothiazide 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 confusion, uneven heart rate, extreme thirst, increased urination, muscle weakness, feeling very thirsty or hot, or being unable to urinate.
What should I avoid while taking chlorothiazide?
Drinking alcohol with chlorothiazide 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.
Chlorothiazide 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;
low levels of sodium in the body--headache, confusion, slurred speech, severe weakness, vomiting, loss of coordination, feeling unsteady;
other signs of an an electrolyte imbalance--dry mouth, thirst, nausea, vomiting, drowsiness, feeling weak or restless, muscle pain, fast heart rate, seizure (convulsions); or
severe skin reaction--fever, sore throat, swelling in your face or tongue, burning in your eyes, skin pain followed by a red or purple skin rash that spreads (especially in the face or upper body) and causes blistering and peeling.
Common side effects may include:
dizziness, spinning sensation;
diarrhea, constipation, stomach cramps;
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.
See also: Side effects (in more detail)
What other drugs will affect chlorothiazide?
Taking chlorothiazide with other drugs that make you light-headed can worsen this effect. Ask your doctor before taking chlorothiazide 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;
insulin or oral diabetes medicine;
steroid medicine; or
This list is not complete. Other drugs may interact with chlorothiazide, 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: 7.01.
More about chlorothiazide
- Chlorothiazide Side Effects
- During Pregnancy or Breastfeeding
- Dosage Information
- Drug Images
- Drug Interactions
- Support Group
- Pricing & Coupons
- En Español
- 1 Review
- Drug class: thiazide diuretics
- Chlorothiazide Injection
- Chlorothiazide Suspension
- Chlorothiazide Tablets
- Chlorothiazide (Advanced Reading)
- Chlorothiazide Intravenous (Advanced Reading)