Millions of Americans use Nexium, Prevacid, Prilosec, or other drugs from a group of medications known as proton-pump inhibitors, or PPIs, to treat frequent heartburn. For some people, the drugs can be helpful. But recent research suggests that people who regularly take these stomach soothers for extended periods face serious harms, including an increased risk of heart attack and dementia.

In the most recent study, researchers followed nearly 200,000 patients treated through the Department of Veterans Affairs (VA) for five years, and found a roughly 20 percent higher risk of kidney disease in those who took PPIs compared with those treated with a different class of heartburn drugs called H2 blockers, such as Pepcid AC and Zantac.

It's not clear exactly how PPIs might harm the kidneys, according to the study authors. One reason might be that the drugs interfere with the body's ability to absorb magnesium; and deficiencies of that mineral could increase the risk of kidney disease. Or the drugs may trigger an allergic reaction that causes swelling inside the kidney and prevents it from working normally.

Other Worrisome Risks of PPI Drugs

All PPIs work by blocking the production of stomach acid. While that helps ulcers heal and prevents heartburn, it also has unintended consequences.

For example, people with reduced stomach acid don’t absorb iron, magnesium, or vitamin B12 as well as those who don't take a PPI. Not absorbing those minerals means that a person could, over time, become deficient.

PPIs may also interfere with the body’s ability to absorb calcium and build bone. In fact, the FDA has warned that taking a PPI may increase your risk of osteoporosis (thinning bones) and hip, spine, and wrist fractures—especially if you use prescription-strength doses, which are higher, or take the drugs for a year or longer.

The acid in your stomach also serves to kill bacteria that cause disease. Because PPIs reduce stomach acid, they can leave people who take the drugs more vulnerable to bacterial infections. Research suggests that taking a PPI may increase your risk of bacterial pneumonia, food poisoning from campylobacter and salmonella bacteria, and an infection caused by the bacterium clostridium difficile (C. diff), which can cause severe diarrhea, fever, and even death. 

By combing through the health records of large groups of patients, researchers have also uncovered other possible associations between taking a PPI and serious harms. In addition to kidney disease, recent research suggest that long-term use of a PPI may increase your risk of: 

  • Heart attack. After analyzing the health records of nearly 3 million people, researchers from Stanford University and the Houston Methodist Research Institute found that taking a PPI increased the risk of heart attack by about 15 percent. The 2015 study found no association between increased heart risk and another type of heartburn drug called an H2 blocker, which includes OTC products such as famotidine (Pepcid AC) and ranitidine (Zantac 75).
  • Dementia. Regular use of PPIs was associated with a 44 percent increased risk of being diagnosed with Alzheimer’s disease or other forms of dementia over 7 years in a study of more than 70,000 people 75 and older published last year in JAMA Neurology.

While looking back at people's health records can reveal possible associations between PPI use and certain illnesses, the findings can’t say for sure that the drugs were the culprit—patients who need acid reducers may be sicker than those who don’t, for example, or might be taking other medications that increase risks.

“The jury is still out on whether those results will hold up after further study,” says M. Michael Wolfe, M.D., chair of the department of medicine at Case Western Reserve University in Cleveland, Ohio.

But for now, he says, this new evidence adds weight to recommendations not to take the powerful medications unless it’s medically necessary.

When Benefits Outweigh Risks

Those risks are “still relatively rare,” says Wolfe, and for some, “clearly outweighed by the benefits of PPIs” for treating painful and potentially serious conditions such as ulcers or gastroesophageal reflux disease (GERD), which occurs when acid from your stomach repeatedly washes up into your esophagus. But those conditions should be diagnosed by a doctor. You should never start taking a potent acid reducer without your doctor's OK, says Wolfe.

For more, read our detailed advice on when you may need a PPI—and when you don't.

Editor's Note: This article and related materials are made possible by a grant from the state Attorney General Consumer and Prescriber Education Grant Program, which is funded by the multistate settlement of consumer-fraud claims regarding the marketing of the prescription drug Neurontin (gabapentin).