Chlorthalidone (patient information)
Why this medication is prescribed
Chlorthalidone, a 'water pill,' is used to treat high blood pressure and fluid retention caused by various conditions, including heart disease. It causes the kidneys to get rid of unneeded water and salt from the body into the urine.
This medicine is sometimes prescribed for other uses; ask your doctor or pharmacist for more information.
How this medication should be used
Chlorthalidone comes as a tablet to take by mouth. It usually is taken once a day or every other day after a meal, preferably breakfast. It is best to take this medicine in the morning to avoid going to the bathroom during the night. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take chlorthalidone exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.
Chlorthalidone controls high blood pressure but does not cure it. Continue to take chlorthalidone even if you feel well. Do not stop taking chlorthalidone without talking to your doctor.
Other uses for this medicine
Chlorthalidone may also be used to treat patients with diabetes insipidus and certain electrolyte disturbances and to prevent kidney stones in patients with high levels of calcium in their blood. Talk to your doctor about the possible risks of using this medicine for your condition.
Special precautions
Before taking chlorthalidonep:
- tell your doctor and pharmacist if you are allergic to chlorthalidone, sulfa drugs, or any other drugs.
- tell your doctor and pharmacist what prescription and nonprescription medications you are taking, especially other medicines for high blood pressure, anti-inflammatory medications such as ibuprofen (Motrin, Nuprin) or naproxen (Aleve), corticosteroids (e.g., prednisone), lithium (Eskalith, Lithobid), medications for diabetes, probenecid (Benemid), and vitamins. If you also are taking cholestyramine or colestipol, take it at least 1 hour after chlorthalidone.
- tell your doctor if you have or have ever had diabetes, gout, or kidney, liver, thyroid, or parathyroid disease.
- tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking chlorthalidone, call your doctor immediately.
- if you are having surgery, including dental surgery, tell the doctor or dentist that you are taking chlorthalidone.
- you should know that this drug may make you drowsy. Do not drive a car or operate machinery until you know how this drug affects you.
- remember that alcohol can add to the drowsiness caused by this drug.
- plan to avoid unnecessary or prolonged exposure to sunlight and to wear protective clothing, sunglasses, and sunscreen. Chlorthalidone may make your skin sensitive to sunlight.
Special dietary instructions
Follow your doctor's directions. They may include following a daily exercise program or a low-salt or low-sodium diet, potassium supplements, and increased amounts of potassium-rich foods (e.g., bananas, prunes, raisins, and orange juice) in your diet.
What to do if you forget a dose
Take the missed dose as soon as you remember it. However, if it is almost time for your next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.
Side Effects
Minor Side Effects
Frequent urination should go away after you take chlorthalidone for a few weeks.
Tell your doctor if any of these symptoms are severe or do not go away:
- muscle weakness
- dizziness
- cramps
- thirst
- stomach pain
- upset stomach
- vomiting
- diarrhea
- loss of appetite
- headache
- hair loss
Severe Side Effects
If you experience any of the following symptoms, call your doctor immediately:
- sore throat with fever
- unusual bleeding or bruising
- severe skin rash with peeling skin
- difficulty breathing or swallowing
If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online [at http://www.fda.gov/MedWatch/report.htm] or by phone [1-800-332-1088].
Storage conditions needed for this medication
Keep this medicine in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom). Throw away any medicine that is outdated or no longer needed. Talk to your pharmacist about the proper disposal of your medicine.
In case of emergency/overdose
In case of overdose, call your local poison control center at 1-800-222-1222. If the victim has collapsed or is not breathing, call local emergency services at 911.
Other information
Keep all appointments with your doctor and the laboratory. Your blood pressure should be checked regularly, and blood tests should be done occasionally.
Do not let anyone else take your medicine. Ask your pharmacist any questions you have about refilling your prescription.
Brand names
- Chlorthalidone Tablets®
- Clorpres®
- Tenoretic®
- Thalitone®