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Hypertension & Stroke



Brand Names: Diurigen, Diuril
Drug Class: Thiazide diuretic
Available in: Tablets, oral suspension, injection
Available Without a Prescription? No
Available as a Generic? Yes

Side Effects

Serious: Skin rash, hives, intense itching, swelling of the mouth and throat, breathing difficulty, serious heartbeat irregularities or palpitations, lightheadedness or dizziness, unusual bleeding or bruising. Call your doctor immediately if you experience any of these side effects.

Common: Potassium depletion may lead to heart palpitations and weakness. Fluid depletion may lead to dizziness, especially upon rising from a sitting or lying position.

Less Common: Decreased sexual ability, increased sensitivity to sunlight, loss of appetite, gout, increased blood sugar (a problem for people with diabetes).

Principal Uses

To treat high blood pressure and conditions causing edema (swelling of body tissues as a result of excess salt and water retention).

How the Drug Works

Diuretics increase the excretion of salt and water in the urine. By reducing the overall fluid volume in the body, these drugs reduce blood volume and so reduce pressure within the blood vessels.


Adults— For high blood pressure: 250 mg once a day. To reduce edema: 250 to 500 mg once a day or 2 or 3 days a week.

Onset of Effect

2 hours after oral dose; 15 minutes after injection.

Duration of Action

6 to 12 hours.

Dietary Advice

Tablets should be taken with food.


Store in a tightly sealed container away from heat and direct light. Keep the liquid form from freezing.

If You Miss a Dose

Take it as soon as you remember. If it is near the time for the next dose, skip the missed dose and resume your regular dosage schedule. Do not double the next dose.

Stopping the Drug

The decision to stop taking the drug should be made by your doctor.

Prolonged Use

See your doctor regularly for examinations and tests if you must take this medicine for an extended period.


Over 60: No special problems are expected.

Driving and Hazardous Work: No special precautions are necessary.

Alcohol: No special precautions are necessary.

Pregnancy: Chlorothiazide has caused birth defects in animals. Human studies have not been done. This medicine should not be taken during pregnancy unless recommended by your doctor. Other diuretics are preferred in pregnant women.

Breast Feeding:
Chlorothiazide passes into breast milk; avoid or discontinue use during the first month of nursing.

Infants and Children: This drug generally is not prescribed for children.

Special Concerns: Chlorothiazide is usually taken once a day. To prevent it from interfering with sleep, take it in the morning (unless otherwise prescribed by your doctor). If you are taking it for high blood pressure, follow the diet and weight control measures recommended by your doctor. Avoid exposure to sunlight, use a sunblock, or wear protective clothing. This medicine may cause your body to lose potassium. Follow your doctor’s instructions about eating potassium-rich foods or taking a potassium supplement.


Symptoms: Lethargy, dizziness, drowsiness, muscle weakness, cramps, heartbeat irregularities, fainting.

What to Do: Call your doctor, emergency medical services (EMS), or the nearest poison control center immediately.

Drug Interactions

Consult your doctor for specific advice if you are taking anticoagulants, cholestyramine, colestipol, drugs for diabetes, nonsteroidal anti-inflammatory drugs, digitalis drugs, or lithium.

Food Interactions

No known food interactions.

Disease Interactions

Caution is advised when taking chlorothiazide. Consult your doctor if you have any of the following: diabetes, gout, lupus erythematosus, pancreatitis, heart disease, blood vessel disease, liver disease, or kidney disease.


From The Johns Hopkins Consumer Guide to Drugs. You can order this book now on our secure server.


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Hypertension & Stroke

The Hypertension & Stroke White Paper from The Johns Hopkins White Papers series is an annual, in-depth report written by Hopkins physicians.

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