WASHINGTON, D.C. (WPVI) -- A popular over-the-counter heartburn medication might be causing silent damage to blood vessels.
In a lab study, Nexium speeded up the aging of cells that line blood vessels.
Those endothelial cells play a role in heading off heart attacks and strokes.
That may explain past studies showing people using proton pump inhibitors - the class Nexium belongs to - long-term have higher rates of heart attacks, strokes, and kidney failure.
The study was published in the journal Circulation Research.
AstraZeneca, the maker of Nexium, says it's safe used as directed.
However, doctors say many people use it longer than recommended.
Although these drugs are widely used, concerns are mounting over their long-term effects on the body.
Recent studies have demonstrated links between proton pump inhibitors and a range of health conditions.
Heart disease, kidney disease, and dementia have all been linked to PPI usage, though, until now, the mechanisms to explain those findings were unknown.
The FDA says 1 in 14 Americans have used PPIs at least once.
In 2006, an estimated $7 billion was spent on PPIs globally.
In 2015, Nexium created almost $2.5 billion of revenue for AstraZeneca.