Generic Name: Chlorthalidone Brand Name(s): Generics only. No brands available.


What is chlorthalidone used for?

Chlorthalidone is commonly used for treating high blood pressure. It may be used along with other medicines to treat fluid retention caused by certain conditions (e.g., heart failure, liver or kidney problems) or medicines (e.g., corticosteroids, estrogens). It may also be used for other conditions as determined by your doctor.

Chlorthalidone is a thiazide-like diuretic. It works by increasing elimination of sodium and potassium in the urine, which causes more water to be eliminated.

How should I take chlorthalidone?

Use chlorthalidone as directed by your doctor. Check the label on the medicine for exact dosing instructions.

Take chlorthalidone by mouth with food, preferably in the morning.

Chlorthalidone will increase urination. If you are taking 1 dose of chlorthalidone daily, take it in the morning to prevent this from affecting your sleep.

How do I store chlorthalidone?

Chlorthalidone is best stored at room temperature away from direct light and moisture. To prevent drug damage, you should not store chlorthalidone in the bathroom or the freezer. There may be different brands of chlorthalidone that may have different storage needs. It is important to always check the product package for instructions on storage, or ask your pharmacist. For safety, you should keep all medicines away from children and pets.

You should not flush chlorthalidone down the toilet or pour them into a drain unless instructed to do so. It is important to properly discard this product when it is expired or no longer needed. Consult your pharmacist for more details about how to safely discard your product.

Precautions & warnings

What should I know before using chlorthalidone?

Before using this drug, tell your doctor if:

  • You are pregnant or breastfeeding. This is because, while you are expecting or feeding a baby, you should only take medicines on the recommendation of a doctor.
  • You are taking any other medicines. This includes any medicines you are taking which are available to buy without a prescription, such as herbal and complementary medicines.
  • You have allergy with any of active or inactive ingredients of chlorthalidone or other medications.
  • You have any other illnesses, disorders, or medical conditions.
  • You have gout, liver disease, low blood levels of potassium or sodium, kidney disease, or lupus.
  • You have a history of allergy or bronchial asthma.

Chlorthalidone may cause dizziness or lightheadedness. These effects may be worse if you take it with alcohol or certain medicines. Use chlorthalidone with caution. Do not drive or perform other possibly unsafe tasks until you know how you react to it.

Chlorthalidone may cause dizziness, lightheadedness, or fainting; alcohol, hot weather, exercise, or fever may increase these effects. To prevent them, sit up or stand slowly, especially in the morning. Sit or lie down at the first sign of any of these effects.

Chlorthalidone may cause you to become sunburned more easily. Avoid the sun, sunlamps, or tanning booths until you know how you react to chlorthalidone. Use a sunscreen or wear protective clothing if you must be outside for more than a short time.

Patients who take medicine for high blood pressure often feel tired or run down for a few weeks after starting treatment. Be sure to take your medicine even if you may not feel “normal.” Tell your doctor if you develop any new symptoms.

Your doctor may have also prescribed a potassium supplement for you. If so, follow the dosing carefully. Do not start taking additional potassium on your own or change your diet to include more potassium without first checking with your doctor.

Lab tests, including liver function, kidney function, and electrolytes, may be performed while you use chlorthalidone. These tests may be used to monitor your condition or check for side effects. Be sure to keep all doctor and lab appointments.

Chlorthalidone should be used with extreme caution in children; safety and effectiveness in children have not been confirmed.

Is it safe during pregnancy or breastfeeding?

There are no adequate studies in women for determining risk when using chlorthalidone during pregnancy or while breastfeeding. Please always consult with your doctor to weigh the potential benefits and risks before taking chlorthalidone. Chlorthalidone is pregnancy risk category B, according to the US Food and Drug Administration (FDA).

FDA pregnancy risk category reference below:

  • A=No risk
  • B=No risk in some studies
  • C=There may be some risk
  • D=Positive evidence of risk
  • X=Contraindicated
  • N=Unknown

Side effects

What side effects can occur from chlorthalidone?

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most common side effects persist or become bothersome:

  • Constipation
  • Dizziness
  • Headache
  • Lightheadedness, especially when sitting up or standing

Seek medical attention right away if any of these severe side effects occur:

  • Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue)
  • Drowsiness
  • Dry mouth
  • Impotence
  • Inflammation of the pancreas
  • Muscle pain or cramps
  • Nausea
  • Rapid or irregular heartbeat
  • Rash or itching
  • Restlessness
  • Unusual thirst
  • Unusual tiredness or weakness
  • Vomiting
  • Yellowing of the skin or eyes

Not everyone experiences these side effects. There may be some side effects not listed above. If you have any concerns about a side-effect, please consult your doctor or pharmacist.


What drugs may interact with chlorthalidone?

Chlorthalidone may interact with other drugs that you are currently taking, which can change how your drug works or increase your risk for serious side effects. To avoid any potential drug interactions, you should keep a list of all the drugs you are using (including prescription drugs, nonprescription drugs, and herbal products) and share it with your doctor and pharmacist. For your safety, do not start, stop, or change the dosage of any drugs without your doctor’s approval.

Products that may interact with this drug are diazoxide, digitalis glycosides (e.g., digoxin), ketanserin, or lithium because their actions and the risk of their side effects may be increased by chlorthalidone.

Does food or alcohol interact with chlorthalidone?

Chlorthalidone may interact with food or alcohol by altering the way the drug works or increase the risk for serious side effects. Please discuss with your doctor or pharmacist any potential food or alcohol interactions before using this drug.

What health conditions may interact with chlorthalidone?

Chlorthalidone may interact with your health condition. This interaction may worsen your health condition or alter the way the drug works. It is important to always let your doctor and pharmacist know all the health conditions you currently have.


The information provided is not a substitute for any medical advice. You should ALWAYS consult with your doctor or pharmacist before using this chlorthalidone.

What is the dose of chlorthalidone for an adult?

Usual Adult Dose for Hypertension

Initial dose: 25 mg orally once a day.

Titration: Increase to 50 mg orally once a day if response is inadequate; if response is still inadequate, increase to 100 mg orally once a day, or a second antihypertensive drug (step 2 therapy) may be added.

Maintenance dose: 25 to 100 mg orally once a day.

Maximum dose: 100 mg orally once a day.

Usual Adult Dose for Edema

Initial dose: 50 to 100 mg orally once a day, or 100 mg orally every other day; some patients may require 150 to 200 mg orally at these intervals.

Maximum dose: 200 mg orally once a day.

What is the dose of chlorthalidone for a child?

The dosage has not been established in pediatric patients. It may be unsafe for your child. It is always important to fully understand the safety of the drug before using. Please consult with your doctor or pharmacist for more information.

How is chlorthalidone available?

Chlorthalidone is available in the following dosage forms and strengths:

  • Tablet 50 mg; 25 mg; 100 mg; 15 mg

What should I do in case of an emergency or overdose?

In case of an emergency or an overdose, call your local emergency services or go to your nearest emergency room.

What should I do if I miss a dose?

If you miss a dose of chlorthalidone, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and take your regular dose as scheduled. Do not take a double dose.

Hello Health Group does not provide medical advice, diagnosis or treatment.

Review Date: August 7, 2017 | Last Modified: September 2, 2017

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