Chlorthalidone is used to treat high blood pressure (hypertension). Lowering high blood pressure helps prevent strokes, heart attacks, and kidney problems. It is also used to reduce extra salt and water in the body caused by conditions such as heart failure, liver disease, and kidney disease. Decreasing extra salt and water in the body helps to decrease swelling (edema) and breathing problems caused by fluid in the lungs. Chlorthalidone is a "water pill" (diuretic). It increases the amount of urine you make, especially when you first start the medication. It also helps to relax the blood vessels so that blood can flow more easily.
OTHER USES: This section contains uses of this drug that are not listed in the approved professional labeling for the drug but that may be prescribed by your health care professional. Use this drug for a condition that is listed in this section only if it has been so prescribed by your health care professional.
Take this medication by mouth with food as directed by your doctor, usually once daily in the morning. 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.
The dosage is based on your medical condition and response to treatment.
Use this medication regularly to get the most benefit from it. To help you remember, take it at the same time each day. It is important to continue taking this medication even if you feel well. Most people with high blood pressure do not feel sick.
If you also take certain drugs to lower your cholesterol (bile acid-binding resins such as cholestyramine or colestipol), take this product at least 2 hours before or at least 4 hours after these medications.
Tell your doctor if your condition does not improve or if it worsens (such as your blood pressure readings remain high or increase).
To reduce the risk of dizziness and lightheadedness, get up slowly when rising from a sitting or lying position.
Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.
This medication may cause a loss of too much body water (dehydration) and salt/minerals. Tell your doctor right away if you have any symptoms of dehydration or mineral loss, including: extreme thirst, very dry mouth, muscle cramps, weakness, fast/irregular heartbeat, confusion.
Tell your doctor right away if you have any serious side effects, including: fainting, toe/joint pain, change in the amount of urine (not including the normal increase in urine when you first start this drug).
A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.
This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.
In the US -
Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.
In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.
Before taking chlorthalidone, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.
This drug may make you dizzy. Do not drive, use machinery, or do any activity that requires alertness until you are sure you can perform such activities safely. Limit alcoholic beverages.
Too much sweating, diarrhea, or vomiting may cause loss of too much body water (dehydration) and increase your risk of dizziness or lightheadedness. Report prolonged diarrhea or vomiting to your doctor. Be sure to drink enough fluids to prevent dehydration unless your doctor directs you otherwise.
Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).
If you have diabetes, this product may affect your blood sugar levels. Check your blood sugar levels regularly as directed by your doctor. Tell your doctor right away if you have symptoms of high blood sugar such as increased thirst and urination. Your doctor may need to adjust your diabetes medication, exercise program, or diet.
This medication may reduce the potassium levels in your blood. Ask your doctor about adding potassium to your diet. A potassium supplement may be prescribed by your doctor.
This medication may make you more sensitive to the sun. Avoid prolonged sun exposure, tanning booths, and sunlamps. Use a sunscreen and wear protective clothing when outdoors.
Older adults may be more sensitive to the side effects of this product, especially dizziness.
During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.
This medication passes into breast milk. Consult your doctor before breast-feeding.
See also How to Use section.
Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.
Some products that may interact with this drug include: cisapride, dofetilide, lithium.
Check the labels on all your medicines (such as cough-and-cold products, diet aids, or NSAIDs such as ibuprofen, naproxen) because they may contain ingredients that could increase your blood pressure or worsen your heart failure. Ask your pharmacist for more details.
This product may interfere with certain laboratory tests (including parathyroid test, protein-bound iodide test), possibly causing false test results. Make sure laboratory personnel and all your doctors know you use this drug.
If overdose is suspected, contact a poison control center or emergency room right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center. Symptoms of overdose may include: severe dizziness, fainting.
Do not share this medication with others.
Lifestyle changes that may help this medication work better include stress reduction programs, exercise, and dietary changes. Talk to your doctor or pharmacist about lifestyle changes that might benefit you.
Laboratory and/or medical tests (including kidney function, blood mineral levels such as potassium) should be performed periodically to monitor your progress or check for side effects. Consult your doctor for more details.
Check your blood pressure regularly while taking this medication. Learn how to monitor your own blood pressure at home, and share the results with your doctor.
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 at room temperature away from light and moisture. Do not store in the bathroom. Keep all medications 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.
Information last revised October 2015. Copyright(c) 2015 First Databank, Inc.
With WebMD's Medicine Cabinet, you can check interactions with drugs.Go to medicine cabinet