Chlorothiazide is a diuretic (water pill) that is used to treat 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.

Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose. Use the medicine exactly as directed.

Shake the oral suspension (liquid) before you measure a dose. Use the dosing syringe provided, or use a medicine dose-measuring device (not a kitchen spoon).

Chlorothiazide injection is given as an infusion into a vein. A healthcare provider will give you this injection if you are unable to take the medicine by mouth.

Tell your caregivers if you feel any burning, pain, or swelling around the IV needle when chlorothiazide is injected.

You may need to follow a special diet to keep your potassium from getting too low. Follow all instructions of your doctor or dietitian. Learn about the foods to eat or avoid to help control your condition.

Your blood pressure will need to be checked often.

Some things can cause your blood pressure to get too low. This includes vomiting, diarrhea, or heavy sweating. Call your doctor if you are sick with vomiting or diarrhea.

This medicine can affect the results of certain medical tests. Tell any doctor who treats you that you are using chlorothiazide.

If you have 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.

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.

Tell your doctor if you have ever had:

• kidney disease;

• liver disease;

• asthma;

• gout;

• diabetes;

• lupus; or

• 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.

You should not breast-feed while using this medicine.

Chlorothiazide is not approved for use by anyone younger than 18 years old.

Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.

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.

Drinking alcohol with chlorothiazide can cause side effects.

Avoid getting up too fast from a sitting or lying position, or you may feel dizzy.

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.

Get emergency medical help if you have signs of an allergic reaction (hives, difficult breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning eyes, skin pain, red or purple skin rash with blistering and peeling).

Chlorothiazide may cause serious side effects. 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;

• low blood cell counts--pale or yellowed skin, dark colored urine, fever, easy bruising or bleeding; or

• signs of an electrolyte imbalance--dry mouth, increased thirst or urination, confusion, vomiting, constipation, muscle pain or weakness, leg cramps, dizziness, drowsiness, lack of energy, feeling restless, fast heartbeats, tingly feeling.

Common side effects of chlorothiazide may include:

• dizziness, spinning sensation;

• numbness or tingling;

• diarrhea, constipation, stomach cramps;

• blurred vision;

• 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.

Using chlorothiazide with other drugs that make you dizzy can worsen this effect. Ask your doctor before using opioid medication, a sleeping pill, a muscle relaxer, or medicine for anxiety or seizures.

Tell your doctor about all your other medicines, especially:

• other blood pressure medications;

• cholestyramine or colestipol;

• lithium;

• insulin or oral diabetes medicine;

• steroid medicine; or

• NSAIDs (nonsteroidal anti-inflammatory drugs)--aspirin, ibuprofen (Advil, Motrin), naproxen (Aleve), celecoxib, diclofenac, indomethacin, meloxicam, and others.

This list is not complete. Other drugs may affect chlorothiazide, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.