A major study from Columbia University has shed new light on the safety of two common medications used to treat high blood pressure: chlorthalidone and hydrochlorothiazide.
These medicines are widely used around the world to lower blood pressure and help prevent serious conditions like heart attacks, strokes, and heart failure. But while both drugs are effective, the study shows that one may come with more health risks than the other.
The study followed over 730,000 people over a period of 17 years, making it one of the largest and most detailed comparisons of these medications ever conducted. What the researchers found was important—patients who took chlorthalidone had a much higher risk of developing a dangerous condition called hypokalemia, which is when potassium levels in the body drop too low.
Potassium is essential for the heart, nerves, and muscles to work properly. Without enough of it, people can experience irregular heartbeats, confusion, muscle weakness, and even kidney failure. In this study, about 6.3% of people on chlorthalidone developed hypokalemia, compared to only 1.9% of those who took hydrochlorothiazide.
But that wasn’t the only concern. People taking chlorthalidone also had a higher chance of other side effects, such as problems with their kidneys and imbalances in other important minerals in the body. These side effects showed up even when chlorthalidone was given at lower doses, which raises serious questions about whether it is the safest choice for many patients.
This new information has sparked discussions among doctors and researchers. For years, some medical guidelines have recommended chlorthalidone over hydrochlorothiazide because it stays in the body longer, which can help lower blood pressure more steadily.
But now, with this large study showing a higher risk of side effects, some experts are asking whether hydrochlorothiazide—despite being milder—might be a better option for many people.
Managing high blood pressure is extremely important. Left untreated, it can cause serious problems such as strokes, heart attacks, kidney damage, and even death. That’s why doctors often use medications like chlorthalidone or hydrochlorothiazide to keep blood pressure under control.
But medicine is only one part of the solution. People with high blood pressure are also encouraged to make healthy lifestyle changes—like eating a balanced diet, exercising regularly, cutting back on alcohol, quitting smoking, and managing stress.
It’s also important for patients to check their blood pressure at home and keep in touch with their doctors to make sure their treatment is working well. Every person is different, and what works for one person might not work for another. This is why personalizing treatment—choosing the right medicine at the right dose—is key.
This study, led by researcher George Hripcsak and published in JAMA Internal Medicine, reminds us that even medicines that seem similar can have very different effects. It’s not just about lowering blood pressure—it’s about doing it safely.
For patients and doctors, these findings offer important information to help choose the best and safest treatment. As research continues, the goal is to give everyone with high blood pressure the best chance at a healthy life.
If you care about high blood pressure, please read studies that drinking tea could help lower blood pressure, and early time-restricted eating could help improve blood pressure.
For more health information, please see recent studies about added sugar in your diet linked to higher blood pressure, and results showing vitamin D could improve blood pressure in people with diabetes.
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