Frequent and prolonged use of proton pump inhibitors (PPIs) such as Prilosec and Nexium has been implicated in a wide range of health issues that include arterial injury, osteoporosis, dementia, ascetes (fluid build-up in the abdominal cavity) and kidney disease. On the matter of kidneys, recent research now shows that PPIs can contribute to the formation of painful kidney stones.

For those who have never suffered from the condition, kidney stones are hard deposits caused by a buildup of mineral salts (usually some form of calcium). These start out small, but can grow in size to the point that they fill the hollow structures within the kidney. In some cases, they simply stay there, but they can wind up traveling down the ureter (the tube-like structure that connects the kidneys to the bladder). There, kidney stones can become lodged, blocking the flow of urine. People who are at greatest risk for kidney stones are those over the age of 40.

Although they are not usually life-threatening, kidney stones can be extremely painful. In some cases, medical procedures are required in order to remove or break up kidney stones.

Proton pump inhibitors are generally used to treat common conditions such as acid reflux. They work by slowing or preventing the production of stomach acid. These are mostly over-the-counter medications that include Nexium and Prilosec as well as Prevacid and Zegerid.

The study was carried out by Italian researchers, and included data on over 187,000 subjects. PPIs have long been known to increase the risk of kidney disease, particularly in the elderly. This study compared the effects of PPIs with those known as H2 blockers, which are also used to treat excess stomach acid. Adjustments were made for age, ethnicity, weight, level of physical activity, unrelated health issues, tobacco use and diet. Over the course of several years, over 3200 of the subjects – nearly 2% – developed kidney stones. Interestingly, the risk factor was slightly higher for patients taking H2 blockers. However, patients taking PPIs had lower amounts of calcium and magnesium in their urine – two of the major factors in the formation of kidney stones.

Dr. Pietro Ferraro, who led the study, says that while the use of PPIs and H2 blockers cause a “small increase” in the risk of kidney stones, the results will need to be confirmed in order to determine whether or not that risk factor is connected to certain types of kidney stones. The research was presented at a conference of the American Society of Nephrology in Chicago earlier in November.