High blood pressure is one of the most common health problems in the world. It affects millions of people and often develops slowly over many years without clear symptoms.
Many people do not realize they have high blood pressure until it causes serious damage. If it is not treated properly, it can raise the risk of heart attacks, strokes, heart failure, kidney disease, and early death.
Because of these dangers, doctors often prescribe medication to help keep blood pressure under control and protect the heart and blood vessels.
For decades, two drugs called chlorthalidone and hydrochlorothiazide have been widely used to treat high blood pressure. These medicines belong to a group known as diuretics, which are often called “water pills.”
They work by helping the body remove extra salt and water through urine. This reduces the amount of fluid in the blood vessels and lowers blood pressure. Both drugs have been recommended in treatment guidelines and are commonly prescribed around the world.
Now, a very large and long-term study from Columbia University has raised important concerns about the safety of one of these drugs. The research followed more than 730,000 people who were treated for high blood pressure over a period of 17 years.
This makes it one of the largest studies ever to compare these two medications. The researchers carefully examined medical records to understand not only how well the drugs worked, but also what side effects they caused over time.
The results showed that while both drugs were effective at lowering blood pressure and reducing the risk of heart attacks and strokes, chlorthalidone caused significantly more harmful side effects than hydrochlorothiazide.
One of the most serious problems was low potassium levels in the blood, a condition known as hypokalemia. Potassium is an essential mineral that helps the heart beat normally and supports nerve and muscle function. When potassium levels drop too low, the body can be thrown out of balance.
The study found that about 6.3 percent of people taking chlorthalidone developed dangerously low potassium levels. In comparison, only 1.9 percent of people taking hydrochlorothiazide had the same problem.
This means the risk was nearly three times higher with chlorthalidone. Low potassium can cause weakness, confusion, muscle cramps, and abnormal heart rhythms. In severe cases, it can lead to kidney failure or even increase the risk of developing type 2 diabetes.
In addition to low potassium, people taking chlorthalidone were more likely to have other electrolyte problems and kidney issues. These risks remained even when doctors prescribed lower doses of the drug, which was surprising to many experts. This suggests that simply reducing the dose may not fully protect patients from harm.
These findings have led doctors and researchers to question whether chlorthalidone should continue to be strongly recommended as a first-choice treatment for high blood pressure.
The study suggests that patients who take this drug may need closer monitoring, including regular blood tests to check potassium and kidney function. For some people, switching to a safer alternative may be the better option.
High blood pressure management is not only about taking pills. Doctors agree that lifestyle changes are just as important. Eating a balanced diet with less salt, staying physically active, managing stress, avoiding smoking, and limiting alcohol can all help lower blood pressure.
Many people also benefit from checking their blood pressure at home so they can catch problems early and work with their doctors to adjust treatment if needed.
The research team, led by George Hripcsak, published their findings in JAMA Internal Medicine. Their work highlights how complex medical treatment can be and why large studies are so important.
A drug that works well is not always the safest choice for everyone. The study reminds both doctors and patients that treatment decisions should be personal and based on both benefits and risks.
This research is an important step toward safer and more effective care for people with high blood pressure. It encourages doctors to look more closely at long-standing practices and helps patients ask informed questions about their treatment options.
If you care about high blood pressure, please read studies that early time-restricted eating could help improve blood pressure, and natural coconut sugar could help reduce blood pressure and artery stiffness.
For more information about blood pressure, please see recent studies about How to eat your way to healthy blood pressure and results showing that Modified traditional Chinese cuisine can lower blood pressure.
Copyright © 2026 Knowridge Science Report. All rights reserved.
