A medication that millions of people use to control high blood pressure may carry more risks than doctors once believed.
New research from Columbia University is raising concerns about chlorthalidone, a common blood pressure drug that has been prescribed for many years.
While the medicine works well to lower blood pressure and protect against heart attacks and strokes, researchers found that it may also increase the risk of several serious side effects.
The study looked at the medical records of more than 730,000 people who were treated for high blood pressure over a period of 17 years. The researchers compared chlorthalidone with another widely used blood pressure medicine called hydrochlorothiazide.
Both drugs belong to a group of medications known as diuretics, often called “water pills.” These medicines help the body remove extra salt and water through urine, which reduces pressure inside blood vessels.
High blood pressure, also known as hypertension, is one of the most common health conditions in the world. It happens when blood pushes too strongly against the walls of the arteries over a long period of time.
Many people do not notice symptoms at first, which is why hypertension is often called a “silent killer.” If left untreated, it can slowly damage important organs including the heart, brain, kidneys, and eyes.
Doctors treat high blood pressure because lowering it can greatly reduce the risk of heart disease, stroke, heart failure, and kidney damage. Along with healthy lifestyle changes such as eating better, exercising, and reducing stress, medications are often necessary to keep blood pressure under control.
Chlorthalidone has long been considered a strong option because it stays in the body longer than some other blood pressure medicines. Many doctors believe it provides more stable blood pressure control throughout the day. In fact, some treatment guidelines have recommended it as a preferred medication for hypertension.
But the new study suggests that the benefits may come with important downsides.
The researchers found that people taking chlorthalidone were much more likely to develop hypokalemia, a condition where potassium levels in the blood become too low. Potassium is an important mineral that helps the body function normally. It supports healthy muscles, nerves, and especially the heart. When potassium levels fall too low, the heart may not beat properly.
Low potassium can cause symptoms such as tiredness, weakness, muscle cramps, constipation, dizziness, or abnormal heart rhythms. In severe cases, it can become life-threatening.
The study showed that 6.3% of patients taking chlorthalidone developed hypokalemia. In comparison, only 1.9% of people taking hydrochlorothiazide experienced the same problem. This means the risk was more than three times higher among chlorthalidone users.
The researchers also discovered that people taking chlorthalidone were more likely to have other electrolyte problems and kidney complications. Electrolytes are minerals in the blood, such as sodium and potassium, that help control many important body functions. When these minerals become unbalanced, it can affect the muscles, nerves, heart, and kidneys.
Kidney problems are especially concerning because the kidneys help filter waste and extra fluid from the blood. Damage to the kidneys can slowly lead to chronic kidney disease, which can seriously affect a person’s health and quality of life.
Even though the findings sound worrying, the researchers stressed that chlorthalidone is not dangerous for everyone. Many people take the medicine safely and benefit from its blood pressure-lowering effects. The study also confirmed that chlorthalidone worked just as well as hydrochlorothiazide in preventing serious cardiovascular problems.
The main message from the research is that patients taking chlorthalidone may need closer monitoring. Regular blood tests can help doctors check potassium levels and kidney function before problems become serious. This allows doctors to adjust medications or recommend treatments if side effects appear.
Experts say patients should not suddenly stop taking their blood pressure medication without speaking to a doctor first. High blood pressure itself is very dangerous when untreated. Instead, patients who feel unusually weak, tired, dizzy, or develop muscle cramps should talk with their healthcare provider about whether their medication may be causing problems.
The study is also part of a larger discussion about balancing the benefits and risks of medications. Many drugs that help one health problem can sometimes create new problems in other parts of the body. This is why long-term studies involving large numbers of patients are important.
Researchers continue to study blood pressure medicines to better understand which treatments are safest and most effective for different groups of people. Some patients may respond better to one medication than another depending on their age, kidney health, diet, and other medical conditions.
Doctors also remind patients that medication is only one part of controlling blood pressure. Healthy daily habits can make a major difference. Eating more fruits and vegetables, lowering salt intake, exercising regularly, avoiding smoking, limiting alcohol, maintaining a healthy weight, and reducing stress can all help support healthy blood pressure naturally.
Simple activities such as walking, yoga, meditation, or improving sleep habits may also help reduce strain on the heart and blood vessels.
The new findings from Columbia University serve as a reminder that even commonly used medications should be carefully monitored. While chlorthalidone remains an effective treatment for high blood pressure, doctors and patients may now need to pay closer attention to possible side effects and discuss whether it is the best choice for each individual.
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.
The study was conducted by researchers at Columbia University.
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