Description: Chlorothiazide reduces the reabsorption of electrolytes from the renal tubules, hence increasing the excretion of Na and Cl ions and consequently of water. It also reduces the GFR.

Onset: W/in 2 hr (oral); 15 min (IV).

Duration: Approx 6-12 hr.


Absorption: Incompletely and variably absorbed from the GI tract. Food may increase the extent of absorption. Time to peak plasma concentration: Approx 4 hr (oral); 30 min (IV).

Distribution: Crosses placenta and excreted in breast milk (small amounts).

Metabolism: Not metabolised.

Excretion: Via urine (as unchanged drug). Plasma half-life: Approx 45-120 min.

This “water pill” (diuretic)  treats high blood pressure by getting rid of extra salt and water. This increases the amount of urine you make. This medication also reduces extra fluid in the body (edema) caused by conditions such as congestive heart failure, liver disease, and kidney disease. Getting rid of extra water helps to reduce fluid in the lungs so that you can breathe easier. It also helps to decrease swelling of the arms, legs, and stomach/abdomen.

This medication may also be used to treat a condition known as “water diabetes” (diabetes insipidus) and to help prevent calcium kidney stones.

How to use chlorothiazide

Take this medication by mouth with or without food, usually once or twice daily or as directed by your doctor. It is best to avoid taking this medication within 4 hours of your bedtime to avoid having to get up to urinate. Consult your doctor or pharmacist if you have questions about your dosing schedule.

If you are taking the suspension, shake the bottle well before each dose. Measure the dose carefully using a medication spoon/cup. Do not use a household spoon.

The dosage is based on your medical condition and response to therapy. In children, the dose is also based on age and weight. The manufacturer recommends that children younger than 2 years should not take more than 375 milligrams per day. Children 2-12 years old should not take more than 1,000 milligrams per day.

Use this medication regularly in order to get the most benefit from it. To help you remember, take it at the same time(s) each day or as prescribed. Do not increase your dose, skip doses, or stop taking this medication unless directed by your doctor. It is important to continue taking this medication even if you feel well. Most people with high blood pressure do not feel sick. For the treatment of high blood pressure, it may take up to several weeks before the full benefit of this drug takes effect.

Cholestyramine and colestipol can decrease the absorption of this medication by your body. If you are taking either of these drugs, separate them from chlorothiazide by at least 4 hours.

Inform your doctor if your condition does not improve or if it worsens (e.g., swelling increases, your routine blood pressure readings increase).

Notify your doctor or pharmacist promptly if any of these effects persist or worsen:

  • Dizziness
  • Lightheadedness
  • Headache
  • blurred vision
  • loss of appetite
  • stomach upset
  • diarrhea
  • constipation
  • decreased sexual ability
  • increased sensitivity to the sun

This medication may cause a loss of too much body water (dehydration) and salt/minerals.

Tell your doctor immediately if numbness/tingling of the arms/legs or joint pain (e.g., big toe pain) occur.

Tell your doctor immediately if any of these rare but very serious side effects occur:

  • signs of infection (e.g., fever, persistent sore throat)
  • easy bruising/bleeding
  • stomach/abdominal pain
  • persistent nausea/vomiting
  • unusual/persistent tiredness
  • yellowing eyes/skin
  • dark urine
  • unusual change in the amount of urine (not including the normal increase in urine when you first start this drug)

Get medical help right away if you decrease in vision, or eye pain.

A very serious allergic reaction to this drug is unlikely.

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.


Consult your doctor regarding these precautions:

  • Allergic reaction to this medication.
  • Patients with severe kidney disease (inability to make urine).
  • Patients with medical history of:
  1. kidney disease
  2. liver disease
  3. untreated salt/mineral imbalance (e.g., imbalance of sodium, potassium, calcium, magnesium)
  4. loss of too much body water (dehydration)
  5. gout
  6. lupus
  7. certain recent nerve surgery (sympathectomy)
  • If you have diabetes, chlorothiazide may affect your blood sugar levels.
  • This drug may reduce the potassium levels in your blood.
  • Avoid prolonged sun exposure, tanning booths, and sunlamps. Use a sunscreen and wear protective clothing when outdoors.
  • Tell your doctor or dentist that you are taking this medication before having surgery.
  • Do not drive, use machinery, or do any activity that requires alertness or clear vision until you are sure you can perform such activities safely.
  • Elderly may be more sensitive to dizziness.
  • Used only when clearly needed during pregnancy.
  • Consult your doctor before breast-feeding.



This drug should not be used with cisapride, and dofetilide because very serious interactions may occur.

Before using this medication, tell your doctor or pharmacist of all prescription and nonprescription/herbal products you may use, especially of:

  • Diazoxide
  • Digoxin
  • Lithium
  • nonsteroidal anti-inflammatory drugs (e.g., ibuprofen, indomethacin)

Check the labels on all your medicines (e.g., cough-and-cold products, diet aids, nonsteroidal anti-inflammatory drugs-NSAIDs for pain/fever reduction) because they may contain ingredients that could increase your blood pressure (e.g., pseudoephedrine, phenylephrine) or reduce the effect of this medication (e.g., ibuprofen, naproxen).

This product can affect the results of certain lab tests.

This document does not contain all possible interactions.


If overdose is suspected, contact a poison control center or emergency room immediately. Symptoms of overdose may include: severe dizziness, severe weakness, fainting.


Do not share this medication with others.

Lifestyle changes such as stress reduction programs, exercise, and dietary changes may increase the effectiveness of this medicine. Talk to your doctor or pharmacist about lifestyle changes that might benefit you.

Laboratory and/or medical tests (e.g., blood mineral levels such as potassium, kidney and liver function tests) should be performed from time to time to monitor your progress or check for side effects. Consult your doctor for more details.

Have your blood pressure checked regularly while taking this medication. Learn how to monitor your own blood pressure, and share the readings with your doctor.

Missed Dose

If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose and resume your usual dosing schedule. Do not double the dose to catch up.


Store in a tightly closed container at room temperature between 59-86 degrees F (15-30 degrees C) away from light and moisture. Do not store in the bathroom. Do not freeze the suspension. Keep all medicines away from children and pets.

Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company for more details about how to safely discard your product.



There are no brands containing this molecule.

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