PPI medications may be among drugs that cause kidney failure, according to scientific studies.

PPIs, or proton pump inhibitors, are commonly used in both prescription and over the counter forms to treat heartburn, acid reflux, peptic ulcers, gastroesophageal reflux disease (GERD), and more. Common PPI drugs include Prilosec, Nexium, and Prevacid.

According to Medical News Today, these drugs treat gastric conditions by inhibiting the production of acid by acid pumps within the stomach.

Although this makes these PPI drugs effective at treating certain gastric conditions, recent studies suggest that the medication may be drugs that cause kidney failure, chronic kidney disease, acute kidney injury, and acute interstitial nephritis.

Although the studies do not prove causation, one of the studies’ lead authors believes it would be reasonable to exercise caution.

“It is very reasonable to assume that PPIs themselves can cause chronic kidney disease,” Dr. Pradeep Arora told WebMD. Arora is a nephrologist and associate professor at the SUNY Buffalo School of Medicine and Biomedical Science. “Patients should only use PPIs for [U.S. Food and Drug Administration]-approved indications, and not to treat simple heartburn or [indigestion].”

Arora’s study analyzed outcomes of over 24,000 patients who developed chronic kidney disease from 2001 to 2008. Chronic kidney disease occurs when a person’s kidneys become too damaged to filter blood like they are supposed to.

The chronic kidney disease study showed that one in four patients who developed the condition had previously been treated with a PPI medication. The study also showed that those taking a PPI drug were reportedly at almost twice the risk of dying prematurely.

The second study which suggested that PPI medications may cause kidney failure was led by Dr. Benjamin Lazarus from Royal Brisbane and Women’s Hospital in Australia and Johns Hopkins University in Baltimore.

The researchers found that users of PPI medications were up to 50 percent more likely to suffer from chronic kidney disease when compared to individuals who had not used PPI drugs. Even after adjusting for the difference between the two research groups, the relationship was reportedly significant.

However, the study showed that the risk was not uniformly increased by stomach acid suppressors. People who took H2-blockers such as Tagamet and Zantec were reportedly not at an increased risk of chronic kidney disease.

According to WebMD, the same team of researchers replicated the link between PPI drugs and chronic kidney disease in a second study that examined data from 240,000 patients between 1997 and 2014.

Other drugs that cause kidney failure include nonsteroidal anti-inflammatory drugs (NSAIDs), a common painkiller class. Some scientists, including Dr. Michael Wolfe from Case Western Reserve University School of Medicine, have suggested that the increased risk for chronic kidney disease may be attributed to NSAID use.

“I suspect if [researchers] correct for NSAID use, they will see this correlation disappear,” Wolfe told WebMD.

Arora reportedly said that his team did not account for the statistical significance of NSAID use although they did control other health conditions which could have skewed the data.

“We did not [control the data for NSAID use], but we have the data for NSAID use and we are looking over that,” he said. “That is a very good point.”