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Chlorthalidone / Chlortalidone

Molecule Description

Chlorthalidone is a (water pill) that reduces increased fluid levels and blood pressure in the body by causing increased urination. It belongs to a group of medicines called ‘Thiazide Diuretics.’

Uses of Chlorthalidone / Chlortalidone

  • High blood pressure (hypertension)
  • Mild to moderate heart failure (impaired efficiency of the heart to pump blood) - Excess fluid conditions in the body (edema) caused due to diseases of the liver (cirrhosis) or the kidney (nephrotic syndrome)
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  • A situation in which an individual urinates excessively losing a lot of water and sodium and is continuously thirsty (diabetes insipidus)

Contraindications of Chlorthalidone / Chlortalidone

When should one not use Chlorthalidone / Chlortalidone

  • Allergy to Chlorthalidone or any of the components of the medicine
  • Not passing any urine (anuria)
  • Severe liver or kidney diseases
  • If you have low blood levels of potassium, sodium or calcium in the blood (weakness, feeling tired, confusion, decreased hunger, muscle twitching, irregular heartbeat)
  • A condition with high levels of uric acid in blood and joints (gout) or kidney stones
  • A disorder where the gland on top of your kidney (adrenal gland) is not functioning properly (Addison's disease)

Side effects of Chlorthalidone / Chlortalidone

Common side effects of this drug are:

  • Low blood levels of potassium (muscle weakness, spasms)
  • Increased blood levels of uric acid and cholesterol
  • Low blood levels of sodium and magnesium (feeling tired, confusion, fits)
  • High blood sugar
  • Skin rashes
  • Low blood pressure, dizziness
  • Stomach upset or decreased hunger
  • Male infertility
  • Pain and swelling of joints in gout (uncommon)
  • Irregular heartbeats, severe muscle weakness, loose motions, breathing and kidney problems (rare, some of them may be serious)

Precautions and Warnings of Chlorthalidone / Chlortalidone


Can I take Chlorthalidone / Chlortalidone during pregnancy?
Chlorthalidone can cause unwanted effects to the mother as well as the unborn baby and hence is recommended not to take during pregnancy.

Breast Feeding

Can I take Chlorthalidone / Chlortalidone while breastfeeding?
It is advised not to use Chlorthalidone during breastfeeding because this medicine is secreted in breast milk and has the potential to harm the child who is breastfed.


Can I drive if I have consumed Chlorthalidone / Chlortalidone?
Chlorthalidone may not affect your ability to drive, but be cautious if you experience symptoms such as dizziness.


Can I consume alcohol with Chlorthalidone / Chlortalidone?
Alcohol also lowers blood pressure and is recommended not to be consumed while taking Chlorthalidone as it will increase the risk of side effects.

Other General Warnings

Talk to your doctor if
  • You have any kidney or liver disease
  • You are on a low-salt diet
  • You have high levels of blood sugar (diabetes mellitus) and cholesterol
  • If you have recently undergone any procedure that requires anaesthesia
  • You are an elderly patient

Mode of Action of Chlorthalidone / Chlortalidone

How Does It Work?

Fluid levels in the body can increase due to improper function of the heart, lungs, kidneys, etc. The increased volume causes high blood pressure to complicate things. Chlorthalidone acts on the kidney and increases the excretion of water and sodium by increasing the urination, thus reducing the blood volume and blood pressure.
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Interactions of Chlorthalidone / Chlortalidone

Interactions with other medicines

  • Other medicines used to treat high blood pressure (Lisinopril, Methyldopa, Propranolol, Bosentan, Amlodipine, Guanethidine)
  • Medicines used to treat allergy or overactive immune reactions (Prednisolone, Betamethasone, Cyclosporine)
  • Anti-cancer medications (Cyclophosphamide, Methotrexate)
  • Hormone therapy with ACTH (Adrenocorticotropic Hormone – treats ulcers of the intestine, joint pains, etc.)
  • Treat asthma (Salbutamol, Formeterol)
  • Anti-diabetes medications (Insulin, Chlorpropamide, Glibenclamide)
  • Medicines that relax muscles (anticholinergics – Atropine, Hyoscine), commonly used for stomach cramps
  • Amphotericin (for fungal infections), Carbenoxolone (treats ulcers), Digoxin (irregular heartbeats), Colestyramine (reduces cholesterol), Allopurinol (for gout), pain killers, lithium (mental illness), Amantadine (Parkinson’s disease and viral infections), calcium salts or Vitamin D
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Interactions with food items

Chlortalidone must be taken in the morning with breakfast. Swallow the tablets with water.

Dietary Restrictions of Chlorthalidone / Chlortalidone

Avoid low salt diets because Chlorthalidone causes excretion of salt along with water. Check with your doctor first before taking this medicine.

Dosage of Chlorthalidone / Chlortalidone


Accidental overdose may not be life-threatening. But high doses of Chlorthalidone can cause dizziness, low blood volume, low blood pressure, electrolyte disturbances, irregular heartbeats, etc. which require immediate medical attention.
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Missed a Dose

Take the medicine as soon as you remember the missed dose.  If the time to your next dose is near (less than 6-8 hours), skip the missed dose, and go back to regular dosing schedule. Ideally, there should be a 12-hour gap between two doses. Do not take a double dose to balance for the missed dose.
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Content Details


Dr. Ritu Budania

MBBS, MD (Pharmacology)

Frequently Asked Questions (FAQs)


Q: What are ‘water pills’? How do they help?

A: Water pills are tablets that cause increased urination. They are also called diuretics. Certain disorders of the heart, lung, liver or kidney cause increased accumulation of fluid levels in the body, making it difficult for the heart to pump, for the kidney to filter and for the liver to metabolize. Failure to remove this excess fluid promptly further increases the water levels leading to high blood pressure, more load on the liver and the kidney and more unwanted effects (such as heart problems, diabetes, etc.) Water pills or diuretics act on the kidney and increase the levels of salt in the kidney. Salt attracts water, and both are excreted by way of excess urination, and this lowers blood volume, blood pressure, and the resulting unwanted effects. Hence, it is important to avoid a low salt diet, while on these medicines.

Q: Is there anything else I need to know before taking Chlorthalidone?

A: Chlorthalidone is good for your heart. Though there are many medicines that control your blood pressure, this medicine is beneficial for the heart. But, the risk of side effects is slightly higher with this medicine, and hence caution is advised. Have a planned diet and monitor your blood sugar levels, liver and kidney functions or for joint pains regularly, to derive more benefits. Do not stop this medicine suddenly as it may cause high blood pressure to return or other side effects such as nervousness or anxiety. Hence inform your doctor if you don’t feel like taking this medicine and he will decrease the dose gradually. Self-medication and self-adjusting the dose with this medicine should be avoided.
Last Updated on: 24 Dec 2020 | 01:48 PM (IST)

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The information provided herein is accurate, updated and complete as per the best practices of the Company. Please note that this information should not be treated as a replacement for physical medical consultation or advice. We do not guarantee the accuracy and the completeness of the information so provided. The absence of any information and/or warning to any drug shall not be considered and assumed as an implied assurance of the Company. We do not take any responsibility for the consequences arising out of the aforementioned information and strongly recommend you for a physical consultation in case of any queries or doubts. Please click here for detailed T&C.
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