Prilosec … Nexus … Prevacid. They are among the most prescribed medications for heartburn–more than 15 million prescriptions were filled in the United States in 2013 alone. But now a new study suggests that people who take these or other proton-pump inhibitors (PPIs) have a higher risk of developing chronic kidney disease.

The study, published in the January 11, 2016 issue of JAMA Internal Medicine, followed more than 10,000 people for more than a decade, and looked at the health records of nearly 250,000 additional people. The results showed that those who took PPIs had up to a 50% higher risk of developing kidney disease. Even compared with other heartburn sufferers, those taking PPIs had a nearly 40% increased risk of kidney disease compared with people taking another type of heartburn medication called H2 Blockers (found in the drugs Pepcid, Tagamet, and Zantac).

These findings are especially significant because medical professionals originally considered PPIs to be very safe drugs. Over the years, other studies linked PPIs to heart problems, bone fractures, and infections.

Doctors now believe that many PPI prescriptions may be unnecessary, and that heartburn might be successfully treated with other medications, or with lifestyle changes, such as stopping smoking and reducing alcohol intake. If you are currently taking a PPI for heartburn, indigestion, or other symptom, talk with your doctor about what alternatives are available.