Drugs Like Tylenol May Alter Heart Function, Study Says—How Much Is Safe

A senior man taking medicine with a glass of water — iStock / FG Trade

When used according to directions, over-the-counter (OTC) pain medications like Tylenol can be incredibly helpful in treating aches, pains, and symptoms that come along with certain illnesses. Of course, like any other drug, there are always potentially risky side effects; in this case, acetaminophen, this class of drug's active ingredient, is typically associated with liver issues. But now, new research has found that drugs like Tylenol could also alter heart function when taken at certain dosages, possibly changing our understanding of just how much could be considered safe.

The latest comes from a study first presented at the American Physiological Society last week, which used a mouse model to examine the effects of acetaminophen at different dosages. Researchers compared mice ingesting water dosed with 500 mg of the drug—or the same amount in an extra-strength Tylenol tablet—while a control group received normal water.

The team then compared the two groups after a week. They found that there were significant changes in heart function, including energy production, antioxidant usage, and the breakdown of damaged proteins in the mice that drank water dosed with acetaminophen, according to the press release. Overall, the researchers said more than 20 signaling pathways were affected, far surpassing the two or three they initially expected.

"We were surprised by the findings since we predicted that acetaminophen, when used at these concentrations, would have minimal effects on the heart," Gabriela Del Toro Rivera, the study's first author, told Medical News Today. "While existing literature primarily associates acetaminophen overuse with liver damage, our research suggests that acetaminophen may influence tissues beyond the liver."

The researchers concluded that the results shed light on new questions about how longer-term use of higher doses of the commonly used drug could affect heart health. Other experts agreed that the implications could change some basic understandings.

"The findings indicate that even at moderate doses considered safe for use, acetaminophen may have significant effects on signaling pathways within the heart tissue," Rigved Tadwalkar, MD, a board-certified consultant cardiologist, told Medical News Today. "This suggests that the commonly used painkiller might not be as benign as previously thought, especially when used regularly over time."

This isn't the only time research has established a link between drugs like Tylenol and heart health. In a 2022 study published in the journal Circulation, 110 patients with high blood pressure were randomly assigned to take either a placebo or 1,000 mg of acetaminophen four times a day over two weeks, Harvard Health reported. The non-control group was then switched to a placebo, at which point researchers noticed those taking the drug had seen their blood pressure rise an average of five points.

However, Del Toro Rivera noted that there were still some limitations to their findings, including that results generated in mice may not carry over to humans. However, she added that it warranted further testing and could help doctors better assess patient needs.

"Findings regarding acetaminophen's effects on the heart have the potential to enhance doctor-patient communication by enabling more personalized recommendations, informed decision-making, and proactive management of potential risks associated with its use," she said. "Utilizing acetaminophen for the shortest duration and at the lowest effective dosage appropriate for an individual's ailment is likely advisable."

Best Life offers the most up-to-date information from top experts, new research, and health agencies, but our content is not meant to be a substitute for professional guidance. When it comes to the medication you're taking or any other health questions you have, always consult your healthcare provider directly.

Zachary Mack Zach is a freelance writer specializing in beer, wine, food, spirits, and travel. He is based in Manhattan.Read moreFiled UnderMedicine • NewsSources referenced in this article