Many people take medications every day to manage common health problems such as allergies, depression, or bladder control. These medicines can be very helpful and often improve quality of life.
However, a new study suggests that some widely used drugs may have an unexpected link to heart disease when used over long periods of time.
The research was conducted by scientists at Karolinska Institutet in Sweden and was published in the medical journal BMC Medicine. The study focused on a group of drugs known as anticholinergic medications. These medicines work by blocking the action of a chemical messenger in the body called acetylcholine.
Acetylcholine plays an important role in how nerves communicate with muscles and organs. It helps regulate many body functions, including heart rate, digestion, and bladder control.
When drugs block this chemical signal, they can help treat certain conditions. For example, some anticholinergic drugs are used as antidepressants, while others are used to treat allergies or urinary incontinence. Many antihistamines that people use for seasonal allergies also have anticholinergic effects.
Because these medications are used to treat several common health problems, they are often prescribed to middle‑aged and older adults. Many people also take more than one of these drugs at the same time. When the total exposure to these medications builds up, doctors describe it as a high “anticholinergic burden.”
Earlier studies had already suggested that a high anticholinergic burden might affect the brain. Some research has linked long‑term use of these drugs to memory problems or reduced cognitive ability.
Scientists suspected that blocking acetylcholine might also affect other systems in the body, but the long‑term impact on the heart and blood vessels had not been well studied.
To explore this question, the research team analyzed health data from more than 500,000 people living in Stockholm. All participants were at least 45 years old when the study began. None of them had been diagnosed with cardiovascular disease at the start of the study, although some did have high blood pressure.
The researchers followed these individuals for as long as 14 years. During that time, they tracked how often participants used anticholinergic medications and whether they later developed cardiovascular problems.
Cardiovascular disease includes conditions such as heart attacks, heart failure, irregular heart rhythms, and other disorders that affect the heart and blood vessels.
By comparing medication use with later health outcomes, the researchers discovered a clear pattern. The more anticholinergic drugs people used each year, the higher their risk of developing cardiovascular disease.
Participants who had the highest levels of exposure to these medications had a 71 percent greater risk of experiencing a cardiovascular event compared with people who did not use anticholinergic drugs at all.
The association appeared across several types of heart conditions, but it was particularly strong for heart failure and abnormal heart rhythms, also known as arrhythmias.
Scientists believe this may be related to how anticholinergic drugs affect the parasympathetic nervous system. This system is part of the body’s automatic control network that helps regulate heart rate, blood pressure, and other vital functions. When the signals from this system are disrupted, it may affect how the heart responds to stress and daily activity.
Nanbo Zhu, a postdoctoral researcher at the Department of Neurobiology, Care Sciences and Society at Karolinska Institutet, explained that the research team wanted to understand whether long‑term exposure to these medications could influence heart health over time.
Because many older adults take several medications at once, the total combined effect of these drugs may be important.
Another researcher involved in the study, Hong Xu, said the findings highlight the importance of monitoring medication use carefully. The results do not mean that people should suddenly stop taking these drugs, because many of them provide real benefits and are necessary for treating certain conditions.
However, doctors may need to pay closer attention to the total number of anticholinergic medicines a patient is using.
The researchers also stressed that the study was observational. This means it identified an association between medication use and cardiovascular disease, but it cannot prove that the drugs directly caused the heart problems.
Other factors may also contribute to the increased risk. For example, people who take certain medications may already have underlying health conditions that affect their heart.
Despite these limitations, the study is important because of its large size and long follow‑up period. By studying more than half a million individuals over many years, the researchers were able to identify patterns that smaller studies might miss.
From a clinical perspective, the findings suggest that healthcare providers may need to evaluate medication combinations more carefully, especially for older patients who already have other risk factors for heart disease. Reducing unnecessary anticholinergic medications or choosing alternative treatments when possible could help lower long‑term health risks.
For patients, the study also highlights the importance of discussing all medications with a doctor or pharmacist. Many people take prescription drugs together with over‑the‑counter medicines such as antihistamines for allergies, without realizing that they may have similar effects on the body.
Overall, the research adds to growing evidence that the total “drug burden” a person carries can influence health in ways that may not be obvious at first. While these medications remain useful and often necessary, careful monitoring and personalized treatment decisions may help reduce potential risks in the future.
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The research findings were published in BMC Medicine.
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