Chicago ? Taking such popular heartburn drugs as Nexium, Prevacid or Prilosec for a year or more can raise the risk of a broken hip markedly in people over 50, a large study in Britain found.

The study raises questions about the safety of some of the most widely used and heavily promoted prescription drugs on the market, taken by millions of people.

The researchers speculated that when the drugs reduce acid in the stomach, they also make it more difficult for the body to absorb bone-building calcium. That can lead to weaker bones and fractures.

Hip fractures in the elderly often lead to life-threatening complications. As a result, doctors should make sure patients have good reason to stay on heartburn drugs long term, said study co-author Dr. Yu-Xiao Yang of the University of Pennsylvania School of Medicine.

“The general perception is they are relatively harmless,” Yang said. “They often are used without a clear or justified indication for the treatment.”

Some people find relief from heartburn with over-the-counter antacids such as Tums, Rolaids and Maalox. But for others, those medicines do not work well. Moreover, heartburn can be more than a source of discomfort. People with chronic heartburn can develop painful ulcers in the esophagus, and in rare cases, some can end up with damage that can lead to esophageal cancer.

Dr. Sandra Dial of McGill University in Montreal, who was not involved in the study but has done similar research, said patients should discuss the risks and benefits with their doctors and taper off their use of these medicines if they can.

Nexium, Prevacid and Prilosec are members of a class of drugs known as proton pump inhibitors. The study found a similar but smaller risk of hip fractures for another class of acid-fighting drugs called H2 blockers. Those drugs include Tagamet and Pepcid.

The study, published in today’s Journal of the American Medical Association, looked at medical records of more than 145,000 patients in England, where a large electronic database of records is available for research. The average age of the patients was 77.