A major long-term study has revealed important differences between two commonly used blood pressure medications: chlorthalidone and hydrochlorothiazide.
These drugs are both used to treat high blood pressure and reduce the risk of heart-related problems like heart attacks, strokes, and heart failure. But researchers at Columbia University have found that one of them—chlorthalidone—may come with more serious side effects than the other.
The study followed over 730,000 people for 17 years, making it one of the largest comparisons of its kind. It confirmed that both medicines do their main job well: they lower blood pressure. This is important because high blood pressure affects millions of people around the world and can lead to life-threatening conditions if not treated properly.
However, the researchers found that patients taking chlorthalidone were more likely to experience low levels of potassium in their blood, a condition called hypokalemia. Potassium is a mineral that is essential for the heart, muscles, and nerves to work properly.
If potassium levels drop too low, it can cause serious problems such as muscle weakness, confusion, kidney damage, irregular heartbeats, and even an increased risk of type 2 diabetes.
In this study, 6.3% of people taking chlorthalidone developed low potassium, compared to only 1.9% of those taking hydrochlorothiazide. This means the risk with chlorthalidone was about three times higher. In addition to potassium loss, patients on chlorthalidone were also more likely to develop other electrolyte problems and kidney issues—even when taking lower doses.
These findings are causing experts to rethink which drug should be used first for treating high blood pressure. While chlorthalidone has long been recommended as a strong option, this new evidence shows that its side effects may outweigh its benefits for some people.
Doctors may need to keep a closer watch on patients using this drug or choose a different medication altogether, especially for people who are more vulnerable to side effects.
The study was led by Dr. George Hripcsak and published in JAMA Internal Medicine, a respected medical journal. It highlights the growing importance of personalized treatment.
What works well for one person may not be the best choice for someone else, especially when side effects are taken into account. The key is finding the right balance between lowering blood pressure and keeping the patient safe.
For people living with high blood pressure, this research is a reminder that managing their condition involves more than just taking medicine. Healthy lifestyle habits—like eating nutritious foods, staying physically active, quitting smoking, cutting back on alcohol, and lowering stress—can make a big difference.
Checking blood pressure at home with a monitor can also help people stay informed and notice changes early.
In the end, this study offers valuable information for both doctors and patients. It doesn’t mean chlorthalidone should never be used, but it does show that risks need to be considered carefully. As researchers continue to study these drugs, the goal remains the same: to find treatments that are not only effective, but also safe in the long run.
If you care about high blood pressure, please read studies about potatoes and high blood pressure, and top 10 choices for a blood pressure-friendly diet
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