Generic name: chlorthalidone (klor-THAL-i-done)
Drug class: Thiazide diuretics
Medically reviewed by Drugs.com. Last updated on Nov 7, 2021.
Commonly used brand name(s)
In the U.S.
Available Dosage Forms:
Therapeutic Class: Cardiovascular Agent
Pharmacologic Class: Diuretic
Chemical Class: Thiazide Related
Uses for chlorthalidone
Chlorthalidone is used alone or together with other medicines to treat high blood pressure (hypertension). High blood pressure adds to the workload of the heart and arteries. If it continues for a long time, the heart and arteries may not function properly. This can damage the blood vessels of the brain, heart, and kidneys, resulting in a stroke, heart failure, or kidney failure. High blood pressure may also increase the risk of heart attacks. These problems may be less likely to occur if blood pressure is controlled.
Chlorthalidone is also used to treat fluid retention (edema) that is caused by congestive heart failure, severe liver disease (cirrhosis), kidney disease, or treatment with a hormone or steroid medicine.
Chlorthalidone is a diuretic (water pill). It reduces the amount of water in the body by increasing the flow of urine, which helps to lower blood pressure.
Chlorthalidone is available only with your doctor's prescription.
Before using chlorthalidone
In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For chlorthalidone, the following should be considered:
Tell your doctor if you have ever had any unusual or allergic reaction to chlorthalidone or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.
Appropriate studies have not been performed on the relationship of age to the effects of chlorthalidone in the pediatric population. Safety and efficacy have not been established.
Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of chlorthalidone in the elderly. However, elderly patients are more likely to have age-related kidney disease, which may require caution and an adjustment in the dose for patients receiving chlorthalidone.
There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.
Interactions with medicines
Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking chlorthalidone, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.
Using chlorthalidone with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
- Amtolmetin Guacil
- Arsenic Trioxide
- Choline Salicylate
- Flufenamic Acid
- Mefenamic Acid
- Niflumic Acid
- Nimesulide Beta Cyclodextrin
- Salicylic Acid
- Sodium Salicylate
- Tiaprofenic Acid
- Tolfenamic Acid
Using chlorthalidone with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
- Aminolevulinic Acid
Interactions with food/tobacco/alcohol
Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.
Other medical problems
The presence of other medical problems may affect the use of chlorthalidone. Make sure you tell your doctor if you have any other medical problems, especially:
- Anuria (not able to form urine)—Should not be used in patients with this condition.
- Asthma or
- Dehydration or
- Diabetes or
- Gout or
- Hypercalcemia (high calcium in the blood) or
- Hyperlipidemia (high cholesterol or triglycerides in the blood) or
- Hyperuricemia (high uric acid in the blood) or
- Hypochloremic alkalosis (low chlorine in the blood) or
- Hypokalemia (low potassium in the blood) or
- Hypomagnesemia (low magnesium in the blood) or
- Hyponatremia (low sodium in the blood) or
- Hypophosphatemia (low phosphorus in the blood) or
- Hypotension (low blood pressure) or
- Hypovolemia (low blood volume) or
- Kidney failure or
- Systemic lupus erythematosus—Use with caution. May make these conditions worse.
- Kidney disease or
- Liver disease—Use with caution. The effects of the medicine may be increased because of slower removal of the medicine from the body.
Proper use of chlorthalidone
Take chlorthalidone exactly as directed by your doctor to benefit your condition as much as possible. Do not take more of it, do not take it more often, and do not take it for a longer time than your doctor ordered.
To help you remember to take your medicine, try to get into the habit of taking it at the same time each day.
In addition to the use of chlorthalidone, treatment for your high blood pressure may include weight control and changes in the types of foods you eat, especially foods high in sodium or potassium. Your doctor will tell you which of these are most important for you. You should check with your doctor before changing your diet.
Many patients who have high blood pressure will not notice any signs of the problem. In fact, many may feel normal. It is very important that you take your medicine exactly as directed and that you keep your appointments with your doctor even if you feel well.
Remember that chlorthalidone will not cure your high blood pressure, but it does help control it. You must continue to take it as directed if you expect to lower your blood pressure and keep it down. You may have to take high blood pressure medicine for the rest of your life. If high blood pressure is not treated, it can cause serious problems such as heart failure, blood vessel disease, stroke, or kidney disease.
Chlorthalidone is usually taken in the morning with food.
The dose of chlorthalidone will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of chlorthalidone. If your dose is different, do not change it unless your doctor tells you to do so.
The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.
- For oral dosage form (tablets):
- For fluid retention (edema):
- Adults—At first, 50 to 100 milligrams (mg) once a day, or 100 mg once every other day. Your doctor may adjust your dose if needed.
- Children—Use and dose must be determined by your doctor.
- For high blood pressure:
- Chlorthalidone: At first, 25 milligrams (mg) once a day. Your doctor may adjust your dose if needed.
- Thalitone®: At first, 15 mg once a day. After 2 weeks, your dose may be increased to 25 mg per day as needed.
- Children—Use and dose must be determined by your doctor.
- For fluid retention (edema):
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 go back to your regular dosing schedule. Do not double doses.
Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.
Keep out of the reach of children.
Do not keep outdated medicine or medicine no longer needed.
Ask your healthcare professional how you should dispose of any medicine you do not use.
Precautions while using chlorthalidone
It is very important that your doctor check your progress at regular visits to make sure chlorthalidone is working properly. Blood tests may be needed to check for unwanted effects.
Dizziness, lightheadedness, or fainting may occur, especially when you get up suddenly from a lying or sitting position. Getting up slowly may help. If the problem continues or gets worse, check with your doctor.
Chlorthalidone may cause you to lose more potassium from your body than normal (hypokalemia). Tell your doctor if you become sick with severe or continuing nausea, vomiting, or diarrhea, and drink fluids to prevent getting dehydrated. Check with your doctor right away if you have dry mouth, increased thirst, muscle cramps, or nausea or vomiting.
Chlorthalidone may cause some people to become dizzy. Do not drive, use machines, or do anything else that could be dangerous if you are dizzy.
Drinking alcoholic beverages may also make the dizziness worse. While you are taking chlorthalidone, be careful to limit the amount of alcohol you drink.
Do not take other medicines unless they have been discussed with your doctor. This especially includes prescription or nonprescription (over-the-counter) medicines for appetite control, asthma, colds, cough, hay fever, or sinus problems.
Chlorthalidone side effects
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor immediately if any of the following side effects occur:
Incidence not known
- Abdominal or stomach pain
- black, tarry stools
- bleeding gums
- blistering, peeling, or loosening of the skin
- blood in the urine or stools
- blurred vision
- burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
- chest pain
- clay-colored stools
- cold sweats
- cough or hoarseness
- coughing up blood
- darkened urine
- difficulty having a bowel movement (stool)
- dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
- dry mouth
- fast heartbeat
- flushed, dry skin
- fruit-like breath odor
- general feeling of tiredness or weakness
- increased hunger
- increased thirst
- increased urination
- itching or skin rash
- joint pain, stiffness, or swelling
- loss of appetite
- lower back or side pain
- pain in the joints or muscles
- painful or difficult urination
- pains in the stomach, side, or abdomen, possibly radiating to the back
- pinpoint red spots on the skin
- red, irritated eyes
- red skin lesions, often with a purple center
- redness, soreness or itching skin
- sore throat
- sores, ulcers, or white spots on the lips or in the mouth
- sores, welting, or blisters
- sugar in the urine
- swelling of the feet or lower legs
- swollen glands
- tightness in the chest
- troubled breathing
- unpleasant breath odor
- unusual bleeding or bruising
- unusual tiredness or weakness
- unusual weight loss
- vomiting of blood
- weight loss
- yellow eyes or skin
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
Incidence not known
- decreased interest in sexual intercourse
- feeling of constant movement of self or surroundings
- inability to have or keep an erection
- increased sensitivity of the skin to sunlight
- loss in sexual ability, desire, drive, or performance
- muscle spasm
- redness or other discoloration of the skin
- sensation of spinning
- severe sunburn
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
More about chlorthalidone
- Side Effects
- During Pregnancy or Breastfeeding
- Dosage Information
- Drug Images
- Drug Interactions
- Pricing & Coupons
- En Español
- 33 Reviews
- Drug class: thiazide diuretics
- Other brands
Related treatment guides
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.