Chlorthalidone (brand names: Hygroton, Thalitone) belongs to a group of drugs called thiazide-like diuretics (water pill) which cause the body to produce urine. It is commonly used to treat high blood pressure. In addition, this blood pressure medication also has other uses and can cause side effects. Please continue reading to learn more.

What does chlorthalidone do to the body?

Chlorthalidone helps the kidneys eliminate excess water and salt from the body in urine. Getting rid of the extra fluid in the body can help lower blood pressure. Therefore, chlorthalidone is used alone or in combination with other blood pressure medications to lower blood pressure in people with hypertension (high blood pressure). 

What is chlorthalidone used to treat?

As mentioned, chlorthalidone is prescribed for high blood pressure. Other uses of this medication include the treatment of edema (swelling or fluid retention) in the body. 

Besides high blood pressure, chlorthalidone is used to decrease swelling caused by congestive heart failure, cirrhosis with end-stage liver disease, and different kidney problems. Chlorthalidone is also used to alleviate swelling associated with steroid medications.  

Some off-label uses of chlorthalidone include the prevention of kidney stones, treatment of hypoparathyroidism, left ventricular hypertrophy, and Meniere disease, an inner ear condition associated with vertigo and hearing loss. A low dose of chlorthalidone is also used to treat high blood pressure in people with type 2 diabetes to lower the risk of cardiovascular events. 

All the indications of chlorthalidone are not listed here. Talk to your doctor or pharmacist if you have any questions about other uses of chlorthalidone. 

Off-label medication use is when a clinician prescribes a medication for an indication different from those approved by the U.S. Food and Drug Administration (FDA). Specifically, the medication has been approved by the bureau, but the indication your doctor wants to use it has yet to be approved. Did you know that 1 in 5 prescriptions are prescribed for off-label use? This practice is common and legal. Your doctor uses their clinical judgment and experience to use certain medications as an “off-label” when they determine that the benefits outweigh the risks. 

What is the adult dose of chlorthalidone?

Your doctor will start you on the lowest effective dose of chlorthalidone and increase the dose based on your response and tolerability of side effects.

For the treatment of hypertension, the starting dose is usually 12.5 mg to 25 milligrams (mg) daily with food. This may be increased to a maximum dose of 100 mg daily if needed. Doctors usually take a cautious approach with older adults and start at the lower end of the dosing range. The maximum daily dose for elderly patients is 25 mg daily.

When used to treat edema, the recommended initial doses are 50 mg to 100 mg daily or 100 mg every other day, with a maximum dosage of 200 mg daily. When used to relieve swelling, doctors typically use lower doses, usually 12.5 mg to 25 mg once daily for elderly patients and those who are in heart failure. 

How to take chlorthalidone?

Chlorthalidone comes in the form of an oral tablet to take by mouth. This medicine is usually taken once a day with food, usually after breakfast. Since this medication is a diuretic (water pill), it’s designed to help you to make more urine than usual. Therefore, taking this medicine in the morning is recommended to avoid getting up during the night to urinate.

Your healthcare professional may ask you to take chlorthalidone every day. Read the prescription label and follow the dosing instructions carefully. Do not adjust the dose or dosage frequency without talking to your healthcare provider. 

Keep in mind that while chlorthalidone can help to control high blood pressure, it cannot cure the condition. Continue taking the medicine even if you don’t have any symptoms. Untreated high blood pressure can put you at risk of heart disease, stroke, and kidney disease. 

If you miss a dose of your medicine, take it as soon as you remember. However, if it is almost time for the next dose, skip the missed dose and take the next dose according to your regular dosing schedule. Do not take a double dose or extra medicine to make up for a missed dose.

What are the side effects of chlorthalidone?

Possible side effects of chlorthalidone include dizziness, cramps, muscle weakness, headache, thirst, stomach pain, vomiting, diarrhea, upset stomach, loss of appetite, and hair loss. Tell your doctor if these side effects are severe or do not go away after a few days once your body has had time to adjust to the medicine.

More serious adverse reactions of chlorthalidone can include sore throat and fever, unusual bleeding or bruising, severe skin rash (allergic reactions), and difficulty breathing or swallowing. Call your doctor or seek emergency medical help if you develop any of these symptoms or other adverse reactions. If you take too much chlorthalidone (overdose), contact your local poison control center or go to the nearest emergency room.

Anaphylactic allergic reaction is a serious allergic reaction that can happen in some cases. You must seek emergency medical attention if you experience the following signs: difficulty breathing, hives, rash, swelling of the face, tongue, lips, or throat.

Who should not take chlorthalidone?

People who have had an allergic reaction to chlorthalidone or other thiazide diuretics in the past should not take this medicine. Before starting treatment, tell your doctor if you have an allergy to chlorthalidone, sulfa drugs, or any other drugs. 

Give your doctor a complete medical history before starting chlorthalidone. Specifically, tell your doctor if you have gout, kidney disease, liver disease, thyroid disease, or parathyroid disease. Pregnant women and women who are nursing an infant with breast milk should discuss the pros and cons of taking this medicine with their provider.

Chlorthalidone can have possible drug interactions with certain drugs, which can increase the risk of serious adverse effects. To avoid possible interactions, give your doctor or pharmacist a complete list of your medications, including prescription drugs, over-the-counter medicines, dietary supplements, and herbal products. 

The following medications can have serious interactions with chlorthalidone leading to severe side effects. Be sure to mention to your doctor if you are taking other blood pressure medications, insulin, diabetes medication, anti-inflammatory drugs like ibuprofen or naproxen, steroid medicines, lithium, and digoxin.

Since chlorthalidone works to lower your blood pressure, it can make you feel dizzy or lightheaded. Talk to your doctor or pharmacist before you start using any medications that can cause sleepiness, such as a muscle relaxer, opioid pain medicine, or medicine for sleep or anxiety. 

What foods should be avoided when taking chlorthalidone?

Drinking alcohol should be avoided when taking chlorthalidone as this can increase your risk of side effects like dizziness, drowsiness, and low blood pressure.

Your doctor may give you dietary instructions to follow while you are on chlorthalidone, such as decreasing extra salt in your diet to help control blood pressure. Your provider may also advise you to take potassium supplements and include increased amounts of potassium-rich foods in your diet, such as bananas, raisins, prunes, and orange juice. This is because chlorthalidone can cause an electrolyte imbalance, such as low levels of potassium, sodium, or magnesium. 

Is chlorthalidone safe to take?

Chlorthalidone is safe when taken exactly as prescribed. However, it can cause serious health issues in some people, such as:

ELECTROLYTE ABNORMALITIES

Chlorthalidone works by helping the kidneys get rid of excess fluid from the body. This also results in the loss of certain electrolytes, such as potassium, sodium, and magnesium. The risk of electrolyte imbalance is higher in people with kidney problems or those taking other medications that can also affect serum electrolytes. Keep all your healthcare appointments during chlorthalidone treatment. Your provider may want to perform regular blood tests to monitor you for electrolyte disturbances. Tell your doctor if you develop symptoms such as severe dizziness, muscle cramps, tingling in the limbs, weakness, or confusion.

KIDNEY PROBLEMS

Kidney injury, including acute renal failure, can be caused by diuretics such as chlorthalidone. Your risk is higher if you have chronic kidney disease, heart failure, or volume depletion. Let your doctor know right away if you notice more swelling in your lower legs, shortness of breath, and newly developed problems with making urine. 

CAUTION WITH LIVER DISEASE

Chlorthalidone works to remove fluids from your body; as a result, it can affect your electrolyte levels. If you have liver disease, you can be at risk for hepatic coma. Let your doctor know if you have liver disease or a history of liver problems. 

DIZZINESS

Chlorthalidone can cause low blood pressure and make you feel lightheaded or dizzy. The risk is greater if you drink alcohol or take other medications that can also cause dizziness. Get up slowly from a sitting or lying position. Tell your doctor if you develop severe dizziness. 

GOUT ATTACKS

Chlorthalidone can raise uric acid levels in the body, increasing the risk of gout attacks. Before starting this medicine, tell your doctor if you have a history of gout. 

BLOOD SUGAR CONTROL

Chlorthalidone can lead to an increase in blood glucose levels. If you have diabetes and measure your blood sugar regularly, tell your provider if you notice higher readings while on chlorthalidone. They might lower the dose of chlorthalidone or switch you to a different blood pressure medication. Get immediate medical help if you develop symptoms of high blood sugar, such as headache, fast or irregular heartbeats, fast breathing, extreme thirst, nausea, vomiting, blurred vision, and fruity-smelling breath. 

References:

1. https://www.ncbi.nlm.nih.gov/books/NBK553174/#
2. https://medlineplus.gov/druginfo/meds/a682342.html#:
3. https://medlineplus.gov/druginfo/meds/a682342.html#
4. https://pubmed.ncbi.nlm.nih.gov/8968014/
5. Product Information: chlorthalidone oral tablets, chlorthalidone oral tablets. Mylan Pharmaceuticals,Inc, Morgantown, WV, 2006.
6. Whelton PK, Carey RM, Aronow WS, et al: 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline for the prevention, detection, evaluation, and management of high blood pressure in adults: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. Hypertension 2018; 71(6):e13-e115.