High blood pressure is one of the most common health problems in the world. It happens when the force of blood pushing against the walls of the blood vessels stays too high for a long time.
Many people do not feel any symptoms, but the damage can slowly build up inside the body. Over the years, high blood pressure can harm the heart, brain, kidneys, and eyes.
It raises the risk of heart attacks and strokes, which are leading causes of death. Because of this, doctors often call it a “silent killer.” Controlling blood pressure is one of the most important ways to protect long‑term health.
Doctors usually suggest healthy habits first, such as eating less salt, staying active, keeping a healthy weight, limiting alcohol, and managing stress. However, many people still need medicine to keep their blood pressure in a safe range. One drug that has been used for decades is chlorthalidone.
It belongs to a group of medicines often called water pills. These drugs help the body remove extra salt and water through urine. With less fluid in the blood vessels, pressure inside them goes down. Because chlorthalidone works well and lasts a long time in the body, many doctors have trusted it for years.
Now, a large new study from Columbia University is raising questions about whether this trusted medicine may cause more side effects than people once thought. The research team examined medical records from more than 730,000 people who were treated for high blood pressure over a period of 17 years.
They compared chlorthalidone with another similar water pill called hydrochlorothiazide. Both medicines lowered blood pressure and helped prevent serious problems such as heart attacks and strokes. In terms of protecting the heart, they worked equally well.
The difference appeared when researchers looked at safety. People taking chlorthalidone were much more likely to develop a condition called hypokalemia, which means the level of potassium in the blood becomes too low.
Potassium is a mineral that the body needs to keep the heart beating normally and to help muscles and nerves work. When potassium drops too low, people may feel very tired, weak, dizzy, or have muscle cramps. In severe cases, it can cause dangerous heart rhythm problems.
In the study, about 6.3 percent of people taking chlorthalidone developed low potassium levels. Among those taking hydrochlorothiazide, only 1.9 percent had this problem. The researchers also found that people on chlorthalidone were more likely to have other chemical imbalances in the blood and signs of kidney trouble.
The kidneys play a key role in cleaning the blood and balancing fluids, so problems in this area can become serious if not treated early.
These findings do not mean that chlorthalidone is unsafe for everyone. Many people take it without any major issues and benefit from lower blood pressure.
However, the study suggests that patients using this drug may need closer monitoring. Simple blood tests can check potassium levels and kidney function. If a problem is found early, doctors can adjust the dose, add supplements, or switch to a different medicine.
People who take chlorthalidone should not stop the medicine on their own. Suddenly stopping can cause blood pressure to rise again, which may be dangerous.
Instead, anyone who feels unusual weakness, strong fatigue, or muscle cramps should speak with a doctor. Treatment decisions are always a balance between benefits and risks, and each person’s health situation is different.
Medicines are only one part of controlling blood pressure. Daily habits still matter greatly. Eating fruits and vegetables, staying physically active, avoiding smoking, and managing stress all help protect the heart. Even small changes, like walking regularly or reducing salty foods, can make a difference over time.
Researchers will continue to study blood pressure drugs to understand their long‑term effects. This new research is a reminder that even long‑used medicines should be checked carefully as new data becomes available.
With good communication between patients and doctors, it is possible to find treatments that are both safe and effective, helping people live longer and healthier lives.
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.
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