For years, people with heart failure have been told to limit how much they drink each day—often no more than 1.5 liters—to avoid fluid buildup.
But a major new study from Radboud University Medical Center in the Netherlands challenges this common advice.
The study, published in Nature Medicine, shows that restricting fluids does not actually help people with stable heart failure—and may even make them feel worse by increasing thirst and reducing comfort.
This is the first large-scale study to investigate the real impact of fluid restriction in heart failure patients. It involved 506 participants across seven hospitals.
Half were told to stick to the usual advice of no more than 1.5 liters of fluid a day, while the other half could drink freely, based on their personal comfort and thirst. Over the course of three months, researchers closely monitored the participants’ health, symptoms, and quality of life.
The results were clear: there were no differences in key health outcomes between the two groups. Whether patients limited their fluid intake or drank as they pleased, their health status, number of hospital visits, medication use, and even survival rates were the same.
The only noticeable difference was that patients who followed the restricted fluid guideline felt more thirsty and more stressed about tracking how much they drank.
Heart failure is a serious condition that affects roughly one in five people during their lifetime, especially those over the age of sixty. It occurs when the heart cannot pump blood properly—either due to weakness in the heart muscle or stiffening of the heart chambers.
This can lead to a buildup of fluid, particularly in the lungs, making breathing more difficult. For this reason, doctors have long believed that drinking less water would reduce the fluid load on the body.
But this theory has never been backed by solid scientific proof. Cardiologist Dr. Roland van Kimmenade, who led the study, explains that the logic behind restricting fluids isn’t as strong as once thought.
“Fluid buildup doesn’t happen in the same way as drinking a glass of water and having it go straight to the lungs,” he said. “It’s a more complex process, and limiting fluid intake doesn’t necessarily prevent the symptoms we’re trying to manage.”
In fact, for many patients, the fluid restriction was more harmful than helpful. It caused frustration, made them feel constantly reminded of their illness, and interfered with daily life.
For example, something as simple as deciding whether to have a cup of tea or coffee with a friend became a source of stress. “It’s not just about thirst,” Van Kimmenade added. “It’s about quality of life.”
On average, the group without restrictions drank only about 300 milliliters more per day—roughly the amount in two small cups of coffee.
This small increase in fluid was enough to relieve thirst, especially in older adults, who typically drink less anyway. Researcher Job Herrmann emphasized how even a slight improvement in comfort can make a big difference for these patients.
Importantly, the study only included stable heart failure patients—those who had not been recently hospitalized and did not have other complications like low sodium levels. So while the findings might not apply to people with more severe or unstable forms of the disease, they are very relevant for the large number of people managing heart failure at home.
The researchers now hope their findings will lead to changes in medical guidelines around the world. “Based on this evidence, we can safely say that stable heart failure patients do not need to follow strict fluid restrictions,” Van Kimmenade said. “This study gives patients more freedom and could improve their everyday lives—starting today.”
If you care about heart disease, please read studies about a big cause of heart failure, and common blood test could advance heart failure treatment.
For more information about heart health, please see recent studies about a new way to repair human heart, and results showing drinking coffee may help reduce heart failure risk.
The research findings can be found in Nature Medicine.
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