A commonly prescribed medicine used to treat high blood pressure and chest pain is receiving new attention after researchers found it may increase the risk of sudden cardiac arrest when taken at high doses.
The medicine, called nifedipine, has been used for many years and is considered effective for lowering blood pressure and improving blood flow. However, a new large study suggests that people taking a daily dose of 60 milligrams may face a much higher risk of sudden cardiac arrest than people who do not use the drug.
The findings have prompted researchers to encourage doctors and patients to carefully consider the benefits and possible risks before using high doses of the medicine.
High blood pressure affects millions of people around the world. If it is left untreated, it can damage blood vessels and increase the risk of heart attacks, strokes, kidney disease, and heart failure.
Doctors often prescribe medicines such as calcium channel blockers to lower blood pressure and reduce these risks. Nifedipine and amlodipine both belong to this group of medicines. They work by relaxing blood vessels so blood can flow more easily, reducing the workload on the heart.
Although these medicines have been available for decades and are widely used, scientists continue to monitor their long-term safety. Sometimes rare side effects are only discovered after very large studies involving thousands of patients. That is because uncommon events can be difficult to detect during smaller clinical trials.
The new research focused on sudden cardiac arrest, one of the most dangerous heart emergencies. Sudden cardiac arrest happens when the heart suddenly stops beating effectively and can no longer pump blood around the body.
The person quickly loses consciousness and stops breathing normally. Without immediate treatment, such as cardiopulmonary resuscitation (CPR) and the use of an automated external defibrillator (AED), the condition is often fatal within minutes.
Sudden cardiac arrest is responsible for about half of all deaths caused by heart disease in Europe and around one in every five natural deaths worldwide. Some people experience warning signs, including chest pain, dizziness, shortness of breath, or a racing heartbeat. However, many people have no warning at all, making prevention especially important.
To investigate whether blood pressure medicines could influence this risk, researchers used information from the Dutch Amsterdam Resuscitation Studies (ARREST) registry.
This large project collects detailed information about people who experience sudden cardiac arrest outside the hospital. The researchers compared more than 2,500 people who suffered sudden cardiac arrest with over 10,000 healthy individuals.
The results showed that people taking a high daily dose of nifedipine, equal to 60 milligrams, were much more likely to experience sudden cardiac arrest than people who were not taking the medicine. In contrast, people taking amlodipine, another widely used calcium channel blocker, did not show the same increase in risk.
Because unexpected findings always need confirmation, the scientists examined a second large database from Denmark. This database included more than 8,000 people who experienced sudden cardiac arrest and over 40,000 healthy comparison participants.
The Danish results matched the findings from the Dutch study, giving researchers greater confidence that the association may be real.
The researchers stress that their study found a link between high-dose nifedipine and sudden cardiac arrest, but it does not prove that the medicine directly causes the condition. More studies are needed to understand exactly why the increased risk was seen and whether certain groups of patients are more vulnerable than others.
For now, experts are not recommending that nifedipine be removed from use. Instead, they advise doctors to carefully review whether a high dose is necessary for each patient. Patients who are already taking nifedipine should never stop the medicine on their own because suddenly stopping blood pressure medication can be dangerous.
Anyone who has concerns should speak with their doctor, who can discuss whether continuing the current treatment or switching to another medicine is the best choice.
This study also highlights why ongoing safety research is so important. Medicines that have helped patients for many years can still reveal new information as larger studies become available. Careful monitoring helps doctors make better treatment decisions and improves patient safety.
As scientists continue to investigate these findings, people can also protect their heart health by controlling blood pressure, eating a balanced diet, exercising regularly, avoiding smoking, maintaining a healthy weight, limiting alcohol, and following their doctor’s advice about medicines.
Together, healthy lifestyle choices and careful use of medication remain the best approach for reducing the risk of serious heart problems.
The findings add an important piece to the understanding of blood pressure treatment and remind both doctors and patients that even well-established medicines should continue to be carefully evaluated as new scientific evidence becomes available.
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