6 Chlorthalidone Interactions to Consider

GoodRx Health

Chlorthalidone is a diuretic ("water pill") that treats high blood pressure and too much fluid in the body (edema). It's commonly prescribed along with other medications to help manage heart-related conditions. But some medications and substances can interact with chlorthalidone in a way that can harm your health.

Here, we'll review six chlorthalidone interactions you should know about. Chlorthalidone is also the active ingredient in Thalitone, a brand-name medication. These medications aren't interchangeable. But the drug interactions described in this article are the same for both versions.

This isn't a complete list of all possible interactions. So be sure to share your medication list with your healthcare team so they can check for any interactions before you start taking chlorthalidone.

1. Lithium

Lithium (Lithobid) is a medication used to treat bipolar disorder and other mental health conditions. Normally, your kidneys clear lithium from your body by removing it through your urine. Chlorthalidone helps your body get rid of extra fluid and sodium through urine. This interferes with the kidneys' removal of lithium and can cause more lithium to stay in your body.

Lithium has a narrow therapeutic index. This means that there's a very small difference between a safe, effective level and a harmful level. So even a small increase in your lithium level can cause potentially dangerous side effects. In severe cases, lithium toxicity can be life-threatening.

Early signs of lithium toxicity include nausea, diarrhea, and tremors. More serious toxicity can cause confusion, slurred speech, and uncontrolled body movements. Seizures and trouble breathing are also possible.

Some prescribers prefer to avoid combining chlorthalidone with lithium. But others are OK with the combination with careful monitoring of your lithium levels.

If you're taking chlorthalidone and lithium at the same time, follow your prescriber's instructions for getting blood work regularly. Be sure to let them know if you notice any new or bothersome side effects - it could be a sign your lithium levels have changed. Seek emergency medical care right away if you develop any symptoms of lithium toxicity.

2. Digoxin

Digoxin (Lanoxin) is a medication that treats heart failure and heart rhythm problems. Like lithium, digoxin has a narrow therapeutic index. And digoxin levels are sensitive to any changes in your electrolyte levels, which include calcium, magnesium, and potassium.

Chlorthalidone can lower your potassium levels, which in turn can increase your digoxin levels. So taking these medications together can raise the risk of digoxin toxicity. Symptoms include nausea, vomiting, and diarrhea. It can also cause blue- or green-tinted vision and a fluttering heartbeat.

Despite this risk, both medications can help manage heart failure, so you may need to take them together. In this case, you'll likely need frequent blood tests to monitor your electrolyte and digoxin levels. Be sure to let your healthcare team know if any new side effects appear. They could be a sign of a change in your digoxin level. Seek emergency care if you have persistent or severe symptoms of digoxin toxicity.

3. Diabetes medications

Chlorthalidone can increase blood glucose (sugar) and make your body less sensitive to insulin. This can make it harder for diabetes medications to work properly.

If you need to take chlorthalidone with diabetes medications, including insulin, you may need to check your blood glucose levels more often to watch for any issues. If your readings are higher than usual, let your prescriber know. They may need to lower your chlorthalidone dosage or make other changes to your medications. But you shouldn't make any changes without your prescriber's OK.

4. Corticosteroids

Corticosteroids, or steroids, are medications that treat various types of inflammation. Examples include hydrocortisone (Cortef), prednisone, and fludrocortisone.

Steroids and chlorthalidone can both lower your potassium levels. So the risk of low potassium (hypokalemia) increases if you take both medications. Mild hypokalemia doesn't usually cause symptoms. But a more severe drop in potassium can cause muscle cramps, weakness, and heart palpitations.

To manage this interaction, your healthcare team will likely keep an eye on your potassium levels. They may also prescribe a potassium supplement, such as potassium chloride (Klor-Con), or recommend more potassium-rich foods if your levels are low. But be sure to let them know if you develop any symptoms of low potassium while taking these medications.

5. Other blood pressure medications

Chlorthalidone is a first-choice medication for high blood pressure. But it may not lower your blood pressure enough by itself. So chlorthalidone is often combined with other blood pressure medications, including:

• Angiotensin-converting enzyme (ACE) inhibitors, such as lisinopril (Zestril)

• Angiotensin receptor blockers (ARBs), such as losartan (Cozaar)

• Calcium channel blockers (CCBs), such as amlodipine (Norvasc)

• Beta blockers, such as atenolol (Tenormin)

These combinations can help you reach your blood pressure goals. But sometimes, taking chlorthalidone with another blood pressure medication can lower your blood pressure too much. This can cause you to feel dizzy or faint, especially when you sit up or stand (known as orthostatic hypotension). It can also increase your chance of falls.

Take your time when changing positions if you start taking another blood pressure medication with chlorthalidone. And let your prescriber know if your blood pressure readings are lower than they should be or you're feeling lightheaded on a regular basis.

6. Medications that lower cholesterol levels

Chlorthalidone may increase your cholesterol levels. This could make any medications you're taking to lower your cholesterol not work as well. Examples of medications used to lower cholesterol are statins, fibrates, and bile acid sequestrants.

If you're taking medication for high cholesterol, your healthcare team will likely check your cholesterol levels after you start taking chlorthalidone. They can adjust your medications as needed to keep your cholesterol levels at a safe level.

Good to know: Bile acid sequestrants, such as colestipol (Colestid) and cholestyramine (Prevalite), can also prevent your body from absorbing chlorthalidone. So you'll need to take these medications at least 4 hours apart to avoid this issue.

Can you drink coffee while taking chlorthalidone?

Yes, but it's probably best to limit how much coffee you drink. The FDA recommends keeping your daily caffeine intake to 400 mg or less. That's about 4 to 5 cups of coffee.

You should also make sure you're drinking plenty of other fluids throughout the day to stay hydrated. Caffeine can act as a diuretic. So the risk of dehydration is higher if you drink a lot of coffee and you're also taking a prescription diuretic, such as chlorthalidone.

If you're concerned about caffeine's effects, try switching to half-caff coffee or green tea. Your healthcare team can also answer any questions about drinking coffee with medications.

Can you take chlorthalidone with other diuretics?

Yes, but only if your healthcare team recommends it. Chlorthalidone is sometimes combined with other types of diuretics for a stronger effect. But taking more than one diuretic can make electrolyte issues more likely. And it can also affect your kidney function. So your prescriber will likely keep an eye out for any issues. Be sure to follow their instructions and keep your appointments to help ensure your safety.

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