One blood pressure drug may be safer than the other, study finds

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A long-term study from Columbia University has found important differences between two common medications used to treat high blood pressure—chlorthalidone and hydrochlorothiazide.

Both drugs help lower blood pressure and reduce the risk of serious health problems like heart attacks, strokes, and heart failure.

But the study shows that one of these drugs may carry a higher risk of side effects than the other.

The researchers followed over 730,000 patients who were taking either chlorthalidone or hydrochlorothiazide. Both medicines belong to a group of drugs called diuretics, which help the body remove extra salt and water through urine.

This helps lower blood pressure by reducing the amount of fluid in the blood vessels. Diuretics have been used for decades and are usually one of the first medicines doctors prescribe for people with high blood pressure.

What the researchers discovered was that chlorthalidone caused more health problems than hydrochlorothiazide. In particular, it was more likely to cause low potassium levels, a condition called hypokalemia. Potassium is a mineral that helps your heart and muscles work properly.

When potassium levels get too low, it can cause serious symptoms such as irregular heartbeats, dizziness, confusion, and muscle weakness. It can also lead to kidney problems and increase the risk of developing type 2 diabetes.

In the study, 6.3% of people taking chlorthalidone developed low potassium levels, while only 1.9% of people taking hydrochlorothiazide had this problem. That means patients on chlorthalidone were more than three times as likely to have dangerously low potassium.

The drug was also linked to other problems, such as electrolyte imbalances and kidney issues. In the worst cases, these side effects could lead to kidney failure or problems with heart rhythm.

For many years, chlorthalidone has been recommended by experts as a good first choice for treating high blood pressure, partly because it lasts longer in the body than hydrochlorothiazide. But this new research suggests that the benefits may not outweigh the risks—especially for people who are already at risk of having low potassium or kidney trouble.

If you’re taking chlorthalidone, this doesn’t mean you need to stop right away. But it may be a good idea to talk with your doctor. In some cases, your doctor may want to check your potassium levels more often, or you might switch to hydrochlorothiazide if it’s a better fit for your health needs.

Treating high blood pressure is very important, because if it’s left untreated, it can lead to heart disease, strokes, and kidney failure. Medicines are often necessary, but they work best when combined with healthy habits.

Eating a balanced diet, exercising regularly, cutting down on salt and alcohol, quitting smoking, and finding ways to manage stress can all help lower your blood pressure naturally. You can also keep track of your progress by checking your blood pressure at home with a simple monitor.

This study was led by Dr. George Hripcsak and published in JAMA Internal Medicine. The findings may lead to changes in how doctors choose medications for high blood pressure. The main message is that it’s not just about bringing the blood pressure numbers down—it’s also about making sure the medicine is safe and doesn’t cause other problems.

As research continues, both doctors and patients will be better able to make informed decisions that protect heart health in the long run.

If you care about high blood pressure, please read studies that early time-restricted eating could help improve blood pressure, and coconut sugar could help reduce blood pressure and artery stiffness.

For more information about blood pressure, please see recent studies about added sugar in your diet linked to higher blood pressure, and results showing plant-based foods could benefit people with high blood pressure.

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